llvm dev - Jul 2018 - Syntax for FileCheck numeric variables and expressions

Hi Alexander,

Please forgive me if I'm missing the obvious but I do not see how the
order helps allowing a comma in the expression. It seems to me that
what would allow it is to make FMTSPEC mandatory or at least the comma
to separate it (ie. [[#,EXPR]] for the default format specifier). In
any case comma in a function-call like expression can be distinguished
from comma for the format specifier since one is always inside a
parenthesized expression.

That said I don't have a strong opinion about the ordering of the
expression wrt. the format specifier. I find EXPR, FMTSPEC more
natural but at 2 persons (James and you) expressed preference for the
reverse order so I'll assume that's the general preference.

Best regards,

Thomas

P.S.: My apologies for only asking now but how do you prefer to be
called? Alexander Vs Alex Vs something else?


On Sun, 22 Jul 2018 at 20:23, Alexander Richardson
<arichardson.kde at gmail.com> wrote:
>
> On Wed, 18 Jul 2018 at 13:50 Thomas Preudhomme <thomas.preudhomme at
linaro.org> wrote:
>>
>> Hi Alex,
>>
>> Thanks for the feedback. My first thought was that introducing the new
>> pseudo var @EXPR is a nice way to generalize that syntax beyond @LINE
>> since it would also evaluate to an arithmetic value. On the other hand
>> there is a small inconsistency because @LINE evaluates to a value
>> which can be part of an expression while @EXPR is an expression, and
>> so the @ syntax as a whole becomes defined as introducing something
>> which is not a regular variable, ie. a negative definition.
>>
>> I'll stick with the # syntax because # is usually associated with
>> numbers and can be defined as introducing an integer
>> expression/variable. The one question I wonder is if the # should be
>> next to the variable name or next to the [[ as proposed by James. I
>> like the former better *but* I think the latter makes more sense since
>> [[#VAR + 1]] would suggest that the [[<something>]] syntax
already
>> allows numeric expression without numeric variable which is not the
>> case. Having the # right at the start also clearly indicates that the
>> whole expression might have a conversion specifier. Finally, the #
>> syntax can allow defining a variable with the result of an arithmetic
>> expression:
>> [[#BAR, %x:]]
>> [[# FOO:BAR+12]]
>>
>> So BAR takes an hex value in lower case syntax, value gets added 12
>> (in decimal) and the result is put into FOO. In which case there
>> should be no format specifier when defining FOO. ie. format specifier
>> for definition is only when there's nothing about the colon. Of
course
>> we could allow hex immediate with 0x syntax if needed. Again, I'm
not
>> advocating for implementing all this from the start, but make sure
>> that the syntax would allow it if we realize we need this later and I
>> think Jame's proposal does.
>>
>> It seems this syntax would suit all your current uses (albeit the
>> rewriting necessary), did I miss something?
>>
>
> Hi Thomas,
>
> That would indeed work fine for me and it would be easy to update our tests
with a few regex replaces.
>
> I think I prefer the [[# %FMTSPEC, EXPR]] syntax since that would also make
it possible to have commas in the expression part. This might be useful if we
allow function-call like expressions such as [[# %X, pow(10, FOO) + 20]].
>
>
> Alex
>
>
>
>>
>> Best regards,
>>
>> Thomas
>>
>> On Tue, 17 Jul 2018 at 21:59, Alexander Richardson
>> <arichardson.kde at gmail.com> wrote:
>> >
>> >
>> >
>> > On Tue, 17 Jul 2018 at 10:02 Thomas Preudhomme via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>> >>
>> >> To be clear, I do not intend to add support for hex specifier
in the
>> >> current patch, I just want to make sure the syntax we choose
is going
>> >> to allow it later. My immediate use case is decimal integer
and I
>> >> intend to write the code so that it's easy to extend to
more type of
>> >> numeric variables and expressions later. This way we'll
only add
>> >> specifier that are actually required by actual testcases.
>> >>
>> >
>> > I also added FileCheck expressions to our fork of LLVM in order to
allow testing both a 128-bit and a 256-bits versions of our CHERI ISA in a
single test case [1].
>> > I used [[@EXPR foo * 2 + 1]] for FileCheck expressions [2].
I'm not particularly happy with this syntax since it is quite verbose (but
then again we don't need it that often so it doesn't really matter). It
also doesn't allow saving the expression result so it needs to be repeated
everywhere. I could probably use [[@EXPR:OUTVAR INVAR + 42]] but I haven't
really had the need for that yet.
>> >
>> > We currently need the following two features:
>> >
>> > - Simple arithmetic with multiple operations. Example:
>> > `cld $gp, $zero, [[@EXPR 2 * $CAP_SIZE - 8]]($c11)`
>> >
>> > - Conversion to hex (upper and lower case since not all tools are
consistent here) and to decimal.
>> > Example: // READOBJ-NEXT: 0x50 R_MIPS_64/R_MIPS_NONE/R_MIPS_NONE
.data 0x[[@EXPR hex($CAP_SIZE * 2)]]
>> >
>> > Alex
>> >
>> > [1] For most test cases the simple -DVAR=value flag in FileCheck
is good enough: we have a %cheri_FileCheck lit substitution that expands to
`FileCheck '-D$CAP_SIZE=16/32'` . This works for most IR level tests
since usually the only thing that is different is "align 16" vs
"align 32". However, when checking the assembly output or linker
addresses we often need something more complex.
>> >
>> > [2] A test case showing all the currently supported expressions
can be found here:
<https://github.com/CTSRD-CHERI/llvm/blob/master/test/FileCheck/expressions.txt>
>> >
>> >
>> >>
>> >> On Mon, 16 Jul 2018 at 18:39, <paul.robinson at
sony.com> wrote:
>> >> >
>> >> >
>> >> >
>> >> > > -----Original Message-----
>> >> > > From: llvm-dev [mailto:llvm-dev-bounces at
lists.llvm.org] On Behalf Of
>> >> > > Thomas Preudhomme via llvm-dev
>> >> > > Sent: Monday, July 16, 2018 6:24 AM
>> >> > > To: jh7370.2008 at my.bristol.ac.uk
>> >> > > Cc: llvm-dev at lists.llvm.org
>> >> > > Subject: Re: [llvm-dev] Syntax for FileCheck numeric
variables and
>> >> > > expressions
>> >> > >
>> >> > > Hi James,
>> >> > >
>> >> > > I like that suggestion very much but I think keeping
the order of the
>> >> > > two sides as initially proposed makes more sense. In
printf/scanf the
>> >> > > string is first because the primary use of these
functions is to do
>> >> > > I/O and so you first specify what you are going to
output/input and
>> >> > > then where to capture variables. The primary
objective of FileCheck
>> >> > > variables and expressions is to capture/print them,
the specifier is
>> >> > > an addon to allow some conversion. Does it make
sense?
>> >> >
>> >> > My immediate reaction is that I'd rather not have
FileCheck get into
>> >> > the business of handling printf specifiers.  OTOH, while
LLVM tools
>> >> > do typically print lowercase hex, that's not
guaranteed, and looking
>> >> > at the output of other tools can be useful too.  So, a
way to specify
>> >> > the case for a hex conversion seems worthwhile.
>> >> >
>> >> > I had also been thinking in terms of the trailing colon
to distinguish
>> >> > definition from use, as James suggested, that's
sort-of consistent
>> >> > with the current syntax.
>> >> >
>> >> > This is starting to make parsing the insides of [[]] much
more involved,
>> >> > so you'll want to pay attention to making that code
well-structured and
>> >> > readable.
>> >> > --paulr
>> >> >
>> >> > >
>> >> > > In the interest of speeding things up I plan to
start implementing
>> >> > > this proposal starting tomorrow unless someone gives
some more
>> >> > > feedback.
>> >> > >
>> >> > > Best regards,
>> >> > >
>> >> > > Thomas
>> >> > >
>> >> > > On Fri, 13 Jul 2018 at 15:51, James Henderson
>> >> > > <jh7370.2008 at my.bristol.ac.uk> wrote:
>> >> > > >
>> >> > > > Hi Thomas,
>> >> > > >
>> >> > > > In general, I think this is a good proposal.
However, I don't think that
>> >> > > using ">" or "<" to
specify base (at least alone) is a good idea, as it
>> >> > > might clash with future ideas to do comparisons etc.
I also think it would
>> >> > > be nice to have the syntax consistent between
definition and use. My first
>> >> > > thought on a reasonable alternative was to use
commas to separate the two
>> >> > > parts, so something like:
>> >> > > >
>> >> > > > [[# VAR, 16:]] to capture a hexadecimal number
(where the spaces are
>> >> > > optional). [[# VAR, 16]] to use a variable,
converted to a hexadecimal
>> >> > > string. In both cases, the base component is
optional, and defaults to
>> >> > > decimal.
>> >> > > >
>> >> > > > This led me to thing that it might be better to
use something similar to
>> >> > > printf style for the latter half, so to capture a
hexadecimal number with
>> >> > > a leading "0x" would be: "0x[[# VAR,
%x:]]" and to use it would be "0x[[#
>> >> > > VAR, %x]]". Indeed, that would allow
straightforward conversions between
>> >> > > formats, so say you defined it by capturing a
decimal integer and using it
>> >> > > to match a hexadecimal in upper case, with leading
0x and 8 digits
>> >> > > following the 0x:
>> >> > > >
>> >> > > > CHECK: [[# VAR, %d:]] # Defines
>> >> > > > CHECK: 0x[[# VAR + 1, %8X]] # Uses
>> >> > > >
>> >> > > > Of course, if we go down that route, it would
probably make more sense
>> >> > > to reverse the two sides (e.g. to become "[[#
%d, VAR:]]" to capture a
>> >> > > decimal and "[[# %8X, VAR + 1]]" to use
it).
>> >> > > >
>> >> > > > Regards,
>> >> > > >
>> >> > > > James
>> >> > > >
>> >> > > > On 12 July 2018 at 15:34, Thomas Preudhomme via
llvm-dev <llvm-
>> >> > > dev at lists.llvm.org> wrote:
>> >> > > >>
>> >> > > >> Hi all,
>> >> > > >>
>> >> > > >> I've written a patch to extend
FileCheck to support matching
>> >> > > >> arithmetic expressions involving variable
[1] (eg. to match REG+1
>> >> > > >> where REG is a variable with a numeric
value). It was suggested to me
>> >> > > >> in the review to introduce the concept of
numeric variable and to
>> >> > > >> allow for specifying the base the value are
written in.
>> >> > > >>
>> >> > > >> [1] https://reviews.llvm.org/D49084
>> >> > > >>
>> >> > > >> I think the syntax should satisfy the below
requirements:
>> >> > > >>
>> >> > > >> * based off the [[]] construct since
anything else might overload an
>> >> > > >> existing valid syntax (eg. $$ is supposed
to match literally now)
>> >> > > >> * consistent with syntax for expressions
using @LINE
>> >> > > >> * consistent with using ':' to
define regular variable
>> >> > > >> * allows to specify base of the number a
numeric variable is being set
>> >> > > to
>> >> > > >> * allows to specify base of the result of
the numeric expression
>> >> > > >>
>> >> > > >> I've come up with the following syntax
for which I'd like feedback:
>> >> > > >>
>> >> > > >> Numeric variable definition:
[[#X<base:]] (eg. [[#ADDR<16:]]) where X
>> >> > > >> is the numeric variable being defined and
<base is optional in which
>> >> > > >> case base defaults to 10
>> >> > > >> Numeric variable use: [[#X>base]] (eg.
[[#ADDR]]>2) where <base is
>> >> > > >> optional in which case base defaults 10
>> >> > > >> Numeric expression: [[exp>base]] (eg.
[[#ADDR+2>16]] where expression
>> >> > > >> must contain at least one numeric variable
>> >> > > >>
>> >> > > >>
>> >> > > >> I'm not a big fan of the > for the
output base being inside the
>> >> > > >> expression but [[exp]]>base would match
>base literally.
>> >> > > >>
>> >> > > >> Any suggestions / opinions?
>> >> > > >>
>> >> > > >> Best regards,
>> >> > > >>
>> >> > > >> Thomas
>> >> > > >>
_______________________________________________
>> >> > > >> LLVM Developers mailing list
>> >> > > >> llvm-dev at lists.llvm.org
>> >> > > >>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>> >> > > >
>> >> > > >
>> >> > > _______________________________________________
>> >> > > LLVM Developers mailing list
>> >> > > llvm-dev at lists.llvm.org
>> >> > >
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>> >> _______________________________________________
>> >> LLVM Developers mailing list
>> >> llvm-dev at lists.llvm.org
>> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Regarding the format, I could be persuaded that either works. In
particular, if one is easier to implement than the other, I'd go with the
easier implementation, personally.

James

On 26 July 2018 at 10:28, Thomas Preudhomme via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi Alexander,
>
> Please forgive me if I'm missing the obvious but I do not see how the
> order helps allowing a comma in the expression. It seems to me that
> what would allow it is to make FMTSPEC mandatory or at least the comma
> to separate it (ie. [[#,EXPR]] for the default format specifier). In
> any case comma in a function-call like expression can be distinguished
> from comma for the format specifier since one is always inside a
> parenthesized expression.
>
> That said I don't have a strong opinion about the ordering of the
> expression wrt. the format specifier. I find EXPR, FMTSPEC more
> natural but at 2 persons (James and you) expressed preference for the
> reverse order so I'll assume that's the general preference.
>
> Best regards,
>
> Thomas
>
> P.S.: My apologies for only asking now but how do you prefer to be
> called? Alexander Vs Alex Vs something else?
>
>
> On Sun, 22 Jul 2018 at 20:23, Alexander Richardson
> <arichardson.kde at gmail.com> wrote:
> >
> > On Wed, 18 Jul 2018 at 13:50 Thomas Preudhomme <
> thomas.preudhomme at linaro.org> wrote:
> >>
> >> Hi Alex,
> >>
> >> Thanks for the feedback. My first thought was that introducing the
new
> >> pseudo var @EXPR is a nice way to generalize that syntax beyond
@LINE
> >> since it would also evaluate to an arithmetic value. On the other
hand
> >> there is a small inconsistency because @LINE evaluates to a value
> >> which can be part of an expression while @EXPR is an expression,
and
> >> so the @ syntax as a whole becomes defined as introducing
something
> >> which is not a regular variable, ie. a negative definition.
> >>
> >> I'll stick with the # syntax because # is usually associated
with
> >> numbers and can be defined as introducing an integer
> >> expression/variable. The one question I wonder is if the # should
be
> >> next to the variable name or next to the [[ as proposed by James.
I
> >> like the former better *but* I think the latter makes more sense
since
> >> [[#VAR + 1]] would suggest that the [[<something>]] syntax
already
> >> allows numeric expression without numeric variable which is not
the
> >> case. Having the # right at the start also clearly indicates that
the
> >> whole expression might have a conversion specifier. Finally, the #
> >> syntax can allow defining a variable with the result of an
arithmetic
> >> expression:
> >> [[#BAR, %x:]]
> >> [[# FOO:BAR+12]]
> >>
> >> So BAR takes an hex value in lower case syntax, value gets added
12
> >> (in decimal) and the result is put into FOO. In which case there
> >> should be no format specifier when defining FOO. ie. format
specifier
> >> for definition is only when there's nothing about the colon.
Of course
> >> we could allow hex immediate with 0x syntax if needed. Again,
I'm not
> >> advocating for implementing all this from the start, but make sure
> >> that the syntax would allow it if we realize we need this later
and I
> >> think Jame's proposal does.
> >>
> >> It seems this syntax would suit all your current uses (albeit the
> >> rewriting necessary), did I miss something?
> >>
> >
> > Hi Thomas,
> >
> > That would indeed work fine for me and it would be easy to update our
> tests with a few regex replaces.
> >
> > I think I prefer the [[# %FMTSPEC, EXPR]] syntax since that would also
> make it possible to have commas in the expression part. This might be
> useful if we allow function-call like expressions such as [[# %X, pow(10,
> FOO) + 20]].
> >
> >
> > Alex
> >
> >
> >
> >>
> >> Best regards,
> >>
> >> Thomas
> >>
> >> On Tue, 17 Jul 2018 at 21:59, Alexander Richardson
> >> <arichardson.kde at gmail.com> wrote:
> >> >
> >> >
> >> >
> >> > On Tue, 17 Jul 2018 at 10:02 Thomas Preudhomme via llvm-dev
<
> llvm-dev at lists.llvm.org> wrote:
> >> >>
> >> >> To be clear, I do not intend to add support for hex
specifier in the
> >> >> current patch, I just want to make sure the syntax we
choose is going
> >> >> to allow it later. My immediate use case is decimal
integer and I
> >> >> intend to write the code so that it's easy to extend
to more type of
> >> >> numeric variables and expressions later. This way
we'll only add
> >> >> specifier that are actually required by actual testcases.
> >> >>
> >> >
> >> > I also added FileCheck expressions to our fork of LLVM in
order to
> allow testing both a 128-bit and a 256-bits versions of our CHERI ISA in a
> single test case [1].
> >> > I used [[@EXPR foo * 2 + 1]] for FileCheck expressions [2].
I'm not
> particularly happy with this syntax since it is quite verbose (but then
> again we don't need it that often so it doesn't really matter). It
also
> doesn't allow saving the expression result so it needs to be repeated
> everywhere. I could probably use [[@EXPR:OUTVAR INVAR + 42]] but I
haven't
> really had the need for that yet.
> >> >
> >> > We currently need the following two features:
> >> >
> >> > - Simple arithmetic with multiple operations. Example:
> >> > `cld $gp, $zero, [[@EXPR 2 * $CAP_SIZE - 8]]($c11)`
> >> >
> >> > - Conversion to hex (upper and lower case since not all tools
are
> consistent here) and to decimal.
> >> > Example: // READOBJ-NEXT: 0x50
R_MIPS_64/R_MIPS_NONE/R_MIPS_NONE
> .data 0x[[@EXPR hex($CAP_SIZE * 2)]]
> >> >
> >> > Alex
> >> >
> >> > [1] For most test cases the simple -DVAR=value flag in
FileCheck is
> good enough: we have a %cheri_FileCheck lit substitution that expands to
> `FileCheck '-D$CAP_SIZE=16/32'` . This works for most IR level
tests since
> usually the only thing that is different is "align 16" vs
"align 32".
> However, when checking the assembly output or linker addresses we often
> need something more complex.
> >> >
> >> > [2] A test case showing all the currently supported
expressions can
> be found here: <https://github.com/CTSRD-CHERI/llvm/blob/master/test/
> FileCheck/expressions.txt>
> >> >
> >> >
> >> >>
> >> >> On Mon, 16 Jul 2018 at 18:39, <paul.robinson at
sony.com> wrote:
> >> >> >
> >> >> >
> >> >> >
> >> >> > > -----Original Message-----
> >> >> > > From: llvm-dev [mailto:llvm-dev-bounces at
lists.llvm.org] On
> Behalf Of
> >> >> > > Thomas Preudhomme via llvm-dev
> >> >> > > Sent: Monday, July 16, 2018 6:24 AM
> >> >> > > To: jh7370.2008 at my.bristol.ac.uk
> >> >> > > Cc: llvm-dev at lists.llvm.org
> >> >> > > Subject: Re: [llvm-dev] Syntax for FileCheck
numeric variables
> and
> >> >> > > expressions
> >> >> > >
> >> >> > > Hi James,
> >> >> > >
> >> >> > > I like that suggestion very much but I think
keeping the order
> of the
> >> >> > > two sides as initially proposed makes more
sense. In
> printf/scanf the
> >> >> > > string is first because the primary use of
these functions is to
> do
> >> >> > > I/O and so you first specify what you are going
to output/input
> and
> >> >> > > then where to capture variables. The primary
objective of
> FileCheck
> >> >> > > variables and expressions is to capture/print
them, the
> specifier is
> >> >> > > an addon to allow some conversion. Does it make
sense?
> >> >> >
> >> >> > My immediate reaction is that I'd rather not
have FileCheck get
> into
> >> >> > the business of handling printf specifiers.  OTOH,
while LLVM tools
> >> >> > do typically print lowercase hex, that's not
guaranteed, and
> looking
> >> >> > at the output of other tools can be useful too.  So,
a way to
> specify
> >> >> > the case for a hex conversion seems worthwhile.
> >> >> >
> >> >> > I had also been thinking in terms of the trailing
colon to
> distinguish
> >> >> > definition from use, as James suggested, that's
sort-of consistent
> >> >> > with the current syntax.
> >> >> >
> >> >> > This is starting to make parsing the insides of [[]]
much more
> involved,
> >> >> > so you'll want to pay attention to making that
code
> well-structured and
> >> >> > readable.
> >> >> > --paulr
> >> >> >
> >> >> > >
> >> >> > > In the interest of speeding things up I plan to
start
> implementing
> >> >> > > this proposal starting tomorrow unless someone
gives some more
> >> >> > > feedback.
> >> >> > >
> >> >> > > Best regards,
> >> >> > >
> >> >> > > Thomas
> >> >> > >
> >> >> > > On Fri, 13 Jul 2018 at 15:51, James Henderson
> >> >> > > <jh7370.2008 at my.bristol.ac.uk> wrote:
> >> >> > > >
> >> >> > > > Hi Thomas,
> >> >> > > >
> >> >> > > > In general, I think this is a good
proposal. However, I don't
> think that
> >> >> > > using ">" or "<" to
specify base (at least alone) is a good
> idea, as it
> >> >> > > might clash with future ideas to do comparisons
etc. I also
> think it would
> >> >> > > be nice to have the syntax consistent between
definition and
> use. My first
> >> >> > > thought on a reasonable alternative was to use
commas to
> separate the two
> >> >> > > parts, so something like:
> >> >> > > >
> >> >> > > > [[# VAR, 16:]] to capture a hexadecimal
number (where the
> spaces are
> >> >> > > optional). [[# VAR, 16]] to use a variable,
converted to a
> hexadecimal
> >> >> > > string. In both cases, the base component is
optional, and
> defaults to
> >> >> > > decimal.
> >> >> > > >
> >> >> > > > This led me to thing that it might be
better to use something
> similar to
> >> >> > > printf style for the latter half, so to capture
a hexadecimal
> number with
> >> >> > > a leading "0x" would be: "0x[[#
VAR, %x:]]" and to use it would
> be "0x[[#
> >> >> > > VAR, %x]]". Indeed, that would allow
straightforward conversions
> between
> >> >> > > formats, so say you defined it by capturing a
decimal integer
> and using it
> >> >> > > to match a hexadecimal in upper case, with
leading 0x and 8
> digits
> >> >> > > following the 0x:
> >> >> > > >
> >> >> > > > CHECK: [[# VAR, %d:]] # Defines
> >> >> > > > CHECK: 0x[[# VAR + 1, %8X]] # Uses
> >> >> > > >
> >> >> > > > Of course, if we go down that route, it
would probably make
> more sense
> >> >> > > to reverse the two sides (e.g. to become
"[[# %d, VAR:]]" to
> capture a
> >> >> > > decimal and "[[# %8X, VAR + 1]]" to
use it).
> >> >> > > >
> >> >> > > > Regards,
> >> >> > > >
> >> >> > > > James
> >> >> > > >
> >> >> > > > On 12 July 2018 at 15:34, Thomas
Preudhomme via llvm-dev <llvm-
> >> >> > > dev at lists.llvm.org> wrote:
> >> >> > > >>
> >> >> > > >> Hi all,
> >> >> > > >>
> >> >> > > >> I've written a patch to extend
FileCheck to support matching
> >> >> > > >> arithmetic expressions involving
variable [1] (eg. to match
> REG+1
> >> >> > > >> where REG is a variable with a numeric
value). It was
> suggested to me
> >> >> > > >> in the review to introduce the concept
of numeric variable
> and to
> >> >> > > >> allow for specifying the base the
value are written in.
> >> >> > > >>
> >> >> > > >> [1] https://reviews.llvm.org/D49084
> >> >> > > >>
> >> >> > > >> I think the syntax should satisfy the
below requirements:
> >> >> > > >>
> >> >> > > >> * based off the [[]] construct since
anything else might
> overload an
> >> >> > > >> existing valid syntax (eg. $$ is
supposed to match literally
> now)
> >> >> > > >> * consistent with syntax for
expressions using @LINE
> >> >> > > >> * consistent with using ':' to
define regular variable
> >> >> > > >> * allows to specify base of the number
a numeric variable is
> being set
> >> >> > > to
> >> >> > > >> * allows to specify base of the result
of the numeric
> expression
> >> >> > > >>
> >> >> > > >> I've come up with the following
syntax for which I'd like
> feedback:
> >> >> > > >>
> >> >> > > >> Numeric variable definition:
[[#X<base:]] (eg. [[#ADDR<16:]])
> where X
> >> >> > > >> is the numeric variable being defined
and <base is optional
> in which
> >> >> > > >> case base defaults to 10
> >> >> > > >> Numeric variable use: [[#X>base]]
(eg. [[#ADDR]]>2) where
> <base is
> >> >> > > >> optional in which case base defaults
10
> >> >> > > >> Numeric expression: [[exp>base]]
(eg. [[#ADDR+2>16]] where
> expression
> >> >> > > >> must contain at least one numeric
variable
> >> >> > > >>
> >> >> > > >>
> >> >> > > >> I'm not a big fan of the > for
the output base being inside
> the
> >> >> > > >> expression but [[exp]]>base would
match >base literally.
> >> >> > > >>
> >> >> > > >> Any suggestions / opinions?
> >> >> > > >>
> >> >> > > >> Best regards,
> >> >> > > >>
> >> >> > > >> Thomas
> >> >> > > >>
_______________________________________________
> >> >> > > >> LLVM Developers mailing list
> >> >> > > >> llvm-dev at lists.llvm.org
> >> >> > > >>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >> >> > > >
> >> >> > > >
> >> >> > > _______________________________________________
> >> >> > > LLVM Developers mailing list
> >> >> > > llvm-dev at lists.llvm.org
> >> >> > >
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >> >> _______________________________________________
> >> >> LLVM Developers mailing list
> >> >> llvm-dev at lists.llvm.org
> >> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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On Thu, 26 Jul 2018 at 10:28 Thomas Preudhomme <thomas.preudhomme at
linaro.org>
wrote:
> Hi Alexander,
>
> Please forgive me if I'm missing the obvious but I do not see how the
> order helps allowing a comma in the expression. It seems to me that
> what would allow it is to make FMTSPEC mandatory or at least the comma
> to separate it (ie. [[#,EXPR]] for the default format specifier). In
> any case comma in a function-call like expression can be distinguished
> from comma for the format specifier since one is always inside a
> parenthesized expression.
>
> Hi Thomas,
I though that FMTSPEC first might be easier to implement because you can
just check if the first non-whitespace character after # is a %. If it is
parse a fmtspec followed by a comma and if not treat everything else as the
expression. But you are right a function-like syntax would always contain
parentheses so there is no ambiguity.
I think [[#,EXPR]]  looks a bit strange and I think we can determine
default format vs format specifier based on the first character after the #
being a % or not. I.e. [[#EXPR]] means default format and [[#%x,EXPR]] is
hex. Does that sound reasonable?


> That said I don't have a strong opinion about the ordering of the
> expression wrt. the format specifier. I find EXPR, FMTSPEC more
> natural but at 2 persons (James and you) expressed preference for the
> reverse order so I'll assume that's the general preference.
>
>
I don't have a strong preference whether it should come before or after and
agree with James that whatever is easiest to implement should be done.

Thanks,
Alex


Best regards,
>
> Thomas
>
> P.S.: My apologies for only asking now but how do you prefer to be
> called? Alexander Vs Alex Vs something else?
>
Most people call me Alex but if you prefer Alexander is also fine.

>
> On Sun, 22 Jul 2018 at 20:23, Alexander Richardson
> <arichardson.kde at gmail.com> wrote:
> >
> > On Wed, 18 Jul 2018 at 13:50 Thomas Preudhomme <
> thomas.preudhomme at linaro.org> wrote:
> >>
> >> Hi Alex,
> >>
> >> Thanks for the feedback. My first thought was that introducing the
new
> >> pseudo var @EXPR is a nice way to generalize that syntax beyond
@LINE
> >> since it would also evaluate to an arithmetic value. On the other
hand
> >> there is a small inconsistency because @LINE evaluates to a value
> >> which can be part of an expression while @EXPR is an expression,
and
> >> so the @ syntax as a whole becomes defined as introducing
something
> >> which is not a regular variable, ie. a negative definition.
> >>
> >> I'll stick with the # syntax because # is usually associated
with
> >> numbers and can be defined as introducing an integer
> >> expression/variable. The one question I wonder is if the # should
be
> >> next to the variable name or next to the [[ as proposed by James.
I
> >> like the former better *but* I think the latter makes more sense
since
> >> [[#VAR + 1]] would suggest that the [[<something>]] syntax
already
> >> allows numeric expression without numeric variable which is not
the
> >> case. Having the # right at the start also clearly indicates that
the
> >> whole expression might have a conversion specifier. Finally, the #
> >> syntax can allow defining a variable with the result of an
arithmetic
> >> expression:
> >> [[#BAR, %x:]]
> >> [[# FOO:BAR+12]]
> >>
> >> So BAR takes an hex value in lower case syntax, value gets added
12
> >> (in decimal) and the result is put into FOO. In which case there
> >> should be no format specifier when defining FOO. ie. format
specifier
> >> for definition is only when there's nothing about the colon.
Of course
> >> we could allow hex immediate with 0x syntax if needed. Again,
I'm not
> >> advocating for implementing all this from the start, but make sure
> >> that the syntax would allow it if we realize we need this later
and I
> >> think Jame's proposal does.
> >>
> >> It seems this syntax would suit all your current uses (albeit the
> >> rewriting necessary), did I miss something?
> >>
> >
> > Hi Thomas,
> >
> > That would indeed work fine for me and it would be easy to update our
> tests with a few regex replaces.
> >
> > I think I prefer the [[# %FMTSPEC, EXPR]] syntax since that would also
> make it possible to have commas in the expression part. This might be
> useful if we allow function-call like expressions such as [[# %X, pow(10,
> FOO) + 20]].
> >
> >
> > Alex
> >
> >
> >
> >>
> >> Best regards,
> >>
> >> Thomas
> >>
> >> On Tue, 17 Jul 2018 at 21:59, Alexander Richardson
> >> <arichardson.kde at gmail.com> wrote:
> >> >
> >> >
> >> >
> >> > On Tue, 17 Jul 2018 at 10:02 Thomas Preudhomme via llvm-dev
<
> llvm-dev at lists.llvm.org> wrote:
> >> >>
> >> >> To be clear, I do not intend to add support for hex
specifier in the
> >> >> current patch, I just want to make sure the syntax we
choose is going
> >> >> to allow it later. My immediate use case is decimal
integer and I
> >> >> intend to write the code so that it's easy to extend
to more type of
> >> >> numeric variables and expressions later. This way
we'll only add
> >> >> specifier that are actually required by actual testcases.
> >> >>
> >> >
> >> > I also added FileCheck expressions to our fork of LLVM in
order to
> allow testing both a 128-bit and a 256-bits versions of our CHERI ISA in a
> single test case [1].
> >> > I used [[@EXPR foo * 2 + 1]] for FileCheck expressions [2].
I'm not
> particularly happy with this syntax since it is quite verbose (but then
> again we don't need it that often so it doesn't really matter). It
also
> doesn't allow saving the expression result so it needs to be repeated
> everywhere. I could probably use [[@EXPR:OUTVAR INVAR + 42]] but I
haven't
> really had the need for that yet.
> >> >
> >> > We currently need the following two features:
> >> >
> >> > - Simple arithmetic with multiple operations. Example:
> >> > `cld $gp, $zero, [[@EXPR 2 * $CAP_SIZE - 8]]($c11)`
> >> >
> >> > - Conversion to hex (upper and lower case since not all tools
are
> consistent here) and to decimal.
> >> > Example: // READOBJ-NEXT: 0x50
R_MIPS_64/R_MIPS_NONE/R_MIPS_NONE
> .data 0x[[@EXPR hex($CAP_SIZE * 2)]]
> >> >
> >> > Alex
> >> >
> >> > [1] For most test cases the simple -DVAR=value flag in
FileCheck is
> good enough: we have a %cheri_FileCheck lit substitution that expands to
> `FileCheck '-D$CAP_SIZE=16/32'` . This works for most IR level
tests since
> usually the only thing that is different is "align 16" vs
"align 32".
> However, when checking the assembly output or linker addresses we often
> need something more complex.
> >> >
> >> > [2] A test case showing all the currently supported
expressions can
> be found here: <
>
https://github.com/CTSRD-CHERI/llvm/blob/master/test/FileCheck/expressions.txt
> >
> >> >
> >> >
> >> >>
> >> >> On Mon, 16 Jul 2018 at 18:39, <paul.robinson at
sony.com> wrote:
> >> >> >
> >> >> >
> >> >> >
> >> >> > > -----Original Message-----
> >> >> > > From: llvm-dev [mailto:llvm-dev-bounces at
lists.llvm.org] On
> Behalf Of
> >> >> > > Thomas Preudhomme via llvm-dev
> >> >> > > Sent: Monday, July 16, 2018 6:24 AM
> >> >> > > To: jh7370.2008 at my.bristol.ac.uk
> >> >> > > Cc: llvm-dev at lists.llvm.org
> >> >> > > Subject: Re: [llvm-dev] Syntax for FileCheck
numeric variables
> and
> >> >> > > expressions
> >> >> > >
> >> >> > > Hi James,
> >> >> > >
> >> >> > > I like that suggestion very much but I think
keeping the order
> of the
> >> >> > > two sides as initially proposed makes more
sense. In
> printf/scanf the
> >> >> > > string is first because the primary use of
these functions is to
> do
> >> >> > > I/O and so you first specify what you are going
to output/input
> and
> >> >> > > then where to capture variables. The primary
objective of
> FileCheck
> >> >> > > variables and expressions is to capture/print
them, the
> specifier is
> >> >> > > an addon to allow some conversion. Does it make
sense?
> >> >> >
> >> >> > My immediate reaction is that I'd rather not
have FileCheck get
> into
> >> >> > the business of handling printf specifiers.  OTOH,
while LLVM tools
> >> >> > do typically print lowercase hex, that's not
guaranteed, and
> looking
> >> >> > at the output of other tools can be useful too.  So,
a way to
> specify
> >> >> > the case for a hex conversion seems worthwhile.
> >> >> >
> >> >> > I had also been thinking in terms of the trailing
colon to
> distinguish
> >> >> > definition from use, as James suggested, that's
sort-of consistent
> >> >> > with the current syntax.
> >> >> >
> >> >> > This is starting to make parsing the insides of [[]]
much more
> involved,
> >> >> > so you'll want to pay attention to making that
code
> well-structured and
> >> >> > readable.
> >> >> > --paulr
> >> >> >
> >> >> > >
> >> >> > > In the interest of speeding things up I plan to
start
> implementing
> >> >> > > this proposal starting tomorrow unless someone
gives some more
> >> >> > > feedback.
> >> >> > >
> >> >> > > Best regards,
> >> >> > >
> >> >> > > Thomas
> >> >> > >
> >> >> > > On Fri, 13 Jul 2018 at 15:51, James Henderson
> >> >> > > <jh7370.2008 at my.bristol.ac.uk> wrote:
> >> >> > > >
> >> >> > > > Hi Thomas,
> >> >> > > >
> >> >> > > > In general, I think this is a good
proposal. However, I don't
> think that
> >> >> > > using ">" or "<" to
specify base (at least alone) is a good
> idea, as it
> >> >> > > might clash with future ideas to do comparisons
etc. I also
> think it would
> >> >> > > be nice to have the syntax consistent between
definition and
> use. My first
> >> >> > > thought on a reasonable alternative was to use
commas to
> separate the two
> >> >> > > parts, so something like:
> >> >> > > >
> >> >> > > > [[# VAR, 16:]] to capture a hexadecimal
number (where the
> spaces are
> >> >> > > optional). [[# VAR, 16]] to use a variable,
converted to a
> hexadecimal
> >> >> > > string. In both cases, the base component is
optional, and
> defaults to
> >> >> > > decimal.
> >> >> > > >
> >> >> > > > This led me to thing that it might be
better to use something
> similar to
> >> >> > > printf style for the latter half, so to capture
a hexadecimal
> number with
> >> >> > > a leading "0x" would be: "0x[[#
VAR, %x:]]" and to use it would
> be "0x[[#
> >> >> > > VAR, %x]]". Indeed, that would allow
straightforward conversions
> between
> >> >> > > formats, so say you defined it by capturing a
decimal integer
> and using it
> >> >> > > to match a hexadecimal in upper case, with
leading 0x and 8
> digits
> >> >> > > following the 0x:
> >> >> > > >
> >> >> > > > CHECK: [[# VAR, %d:]] # Defines
> >> >> > > > CHECK: 0x[[# VAR + 1, %8X]] # Uses
> >> >> > > >
> >> >> > > > Of course, if we go down that route, it
would probably make
> more sense
> >> >> > > to reverse the two sides (e.g. to become
"[[# %d, VAR:]]" to
> capture a
> >> >> > > decimal and "[[# %8X, VAR + 1]]" to
use it).
> >> >> > > >
> >> >> > > > Regards,
> >> >> > > >
> >> >> > > > James
> >> >> > > >
> >> >> > > > On 12 July 2018 at 15:34, Thomas
Preudhomme via llvm-dev <llvm-
> >> >> > > dev at lists.llvm.org> wrote:
> >> >> > > >>
> >> >> > > >> Hi all,
> >> >> > > >>
> >> >> > > >> I've written a patch to extend
FileCheck to support matching
> >> >> > > >> arithmetic expressions involving
variable [1] (eg. to match
> REG+1
> >> >> > > >> where REG is a variable with a numeric
value). It was
> suggested to me
> >> >> > > >> in the review to introduce the concept
of numeric variable
> and to
> >> >> > > >> allow for specifying the base the
value are written in.
> >> >> > > >>
> >> >> > > >> [1] https://reviews.llvm.org/D49084
> >> >> > > >>
> >> >> > > >> I think the syntax should satisfy the
below requirements:
> >> >> > > >>
> >> >> > > >> * based off the [[]] construct since
anything else might
> overload an
> >> >> > > >> existing valid syntax (eg. $$ is
supposed to match literally
> now)
> >> >> > > >> * consistent with syntax for
expressions using @LINE
> >> >> > > >> * consistent with using ':' to
define regular variable
> >> >> > > >> * allows to specify base of the number
a numeric variable is
> being set
> >> >> > > to
> >> >> > > >> * allows to specify base of the result
of the numeric
> expression
> >> >> > > >>
> >> >> > > >> I've come up with the following
syntax for which I'd like
> feedback:
> >> >> > > >>
> >> >> > > >> Numeric variable definition:
[[#X<base:]] (eg. [[#ADDR<16:]])
> where X
> >> >> > > >> is the numeric variable being defined
and <base is optional
> in which
> >> >> > > >> case base defaults to 10
> >> >> > > >> Numeric variable use: [[#X>base]]
(eg. [[#ADDR]]>2) where
> <base is
> >> >> > > >> optional in which case base defaults
10
> >> >> > > >> Numeric expression: [[exp>base]]
(eg. [[#ADDR+2>16]] where
> expression
> >> >> > > >> must contain at least one numeric
variable
> >> >> > > >>
> >> >> > > >>
> >> >> > > >> I'm not a big fan of the > for
the output base being inside
> the
> >> >> > > >> expression but [[exp]]>base would
match >base literally.
> >> >> > > >>
> >> >> > > >> Any suggestions / opinions?
> >> >> > > >>
> >> >> > > >> Best regards,
> >> >> > > >>
> >> >> > > >> Thomas
> >> >> > > >>
_______________________________________________
> >> >> > > >> LLVM Developers mailing list
> >> >> > > >> llvm-dev at lists.llvm.org
> >> >> > > >>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >> >> > > >
> >> >> > > >
> >> >> > > _______________________________________________
> >> >> > > LLVM Developers mailing list
> >> >> > > llvm-dev at lists.llvm.org
> >> >> > >
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >> >> _______________________________________________
> >> >> LLVM Developers mailing list
> >> >> llvm-dev at lists.llvm.org
> >> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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Hi Alex,

On Fri, 27 Jul 2018 at 11:53, Alexander Richardson
<arichardson.kde at gmail.com> wrote:
>
> On Thu, 26 Jul 2018 at 10:28 Thomas Preudhomme <thomas.preudhomme at
linaro.org> wrote:
>>
>> Hi Alexander,
>>
>> Please forgive me if I'm missing the obvious but I do not see how
the
>> order helps allowing a comma in the expression. It seems to me that
>> what would allow it is to make FMTSPEC mandatory or at least the comma
>> to separate it (ie. [[#,EXPR]] for the default format specifier). In
>> any case comma in a function-call like expression can be distinguished
>> from comma for the format specifier since one is always inside a
>> parenthesized expression.
>>
> Hi Thomas,
>
> I though that FMTSPEC first might be easier to implement because you can
just check if the first non-whitespace character after # is a %. If it is parse
a fmtspec followed by a comma and if not treat everything else as the
expression. But you are right a function-like syntax would always contain
parentheses so there is no ambiguity.
> I think [[#,EXPR]]  looks a bit strange and I think we can determine
default format vs format specifier based on the first character after the #
being a % or not. I.e. [[#EXPR]] means default format and [[#%x,EXPR]] is hex.
Does that sound reasonable?
Yes it does. I've started reworking the changes I made to
FileCheck.rst to document the agreed upon syntax. At the moment I'm
thinking about supporting %u, %d, %x and %X as input and output format
specifier, the optionality of format specifier (defaulting to %u) and
basic numeric variable definition and numeric expression use involving
a variable and an immediate. In particular, I do *not* plan to
implement the following:
- defining a numeric variable from a numeric expression
- arithmetic operations other than - and +
- arithmetic expression involving several variables

I'll make sure that this can easily be added later and will mention in
the doc that the syntax for these feature has already been agreed as
well.

Feel free to give me feedback on the set of features I intend to
implement in this initial patch.

Best regards,

Thomas
>
>
>>
>> That said I don't have a strong opinion about the ordering of the
>> expression wrt. the format specifier. I find EXPR, FMTSPEC more
>> natural but at 2 persons (James and you) expressed preference for the
>> reverse order so I'll assume that's the general preference.
>>
>
> I don't have a strong preference whether it should come before or after
and agree with James that whatever is easiest to implement should be done.
>
> Thanks,
> Alex
>
>
>> Best regards,
>>
>> Thomas
>>
>> P.S.: My apologies for only asking now but how do you prefer to be
>> called? Alexander Vs Alex Vs something else?
>
> Most people call me Alex but if you prefer Alexander is also fine.
>
>>
>>
>> On Sun, 22 Jul 2018 at 20:23, Alexander Richardson
>> <arichardson.kde at gmail.com> wrote:
>> >
>> > On Wed, 18 Jul 2018 at 13:50 Thomas Preudhomme
<thomas.preudhomme at linaro.org> wrote:
>> >>
>> >> Hi Alex,
>> >>
>> >> Thanks for the feedback. My first thought was that introducing
the new
>> >> pseudo var @EXPR is a nice way to generalize that syntax
beyond @LINE
>> >> since it would also evaluate to an arithmetic value. On the
other hand
>> >> there is a small inconsistency because @LINE evaluates to a
value
>> >> which can be part of an expression while @EXPR is an
expression, and
>> >> so the @ syntax as a whole becomes defined as introducing
something
>> >> which is not a regular variable, ie. a negative definition.
>> >>
>> >> I'll stick with the # syntax because # is usually
associated with
>> >> numbers and can be defined as introducing an integer
>> >> expression/variable. The one question I wonder is if the #
should be
>> >> next to the variable name or next to the [[ as proposed by
James. I
>> >> like the former better *but* I think the latter makes more
sense since
>> >> [[#VAR + 1]] would suggest that the [[<something>]]
syntax already
>> >> allows numeric expression without numeric variable which is
not the
>> >> case. Having the # right at the start also clearly indicates
that the
>> >> whole expression might have a conversion specifier. Finally,
the #
>> >> syntax can allow defining a variable with the result of an
arithmetic
>> >> expression:
>> >> [[#BAR, %x:]]
>> >> [[# FOO:BAR+12]]
>> >>
>> >> So BAR takes an hex value in lower case syntax, value gets
added 12
>> >> (in decimal) and the result is put into FOO. In which case
there
>> >> should be no format specifier when defining FOO. ie. format
specifier
>> >> for definition is only when there's nothing about the
colon. Of course
>> >> we could allow hex immediate with 0x syntax if needed. Again,
I'm not
>> >> advocating for implementing all this from the start, but make
sure
>> >> that the syntax would allow it if we realize we need this
later and I
>> >> think Jame's proposal does.
>> >>
>> >> It seems this syntax would suit all your current uses (albeit
the
>> >> rewriting necessary), did I miss something?
>> >>
>> >
>> > Hi Thomas,
>> >
>> > That would indeed work fine for me and it would be easy to update
our tests with a few regex replaces.
>> >
>> > I think I prefer the [[# %FMTSPEC, EXPR]] syntax since that would
also make it possible to have commas in the expression part. This might be
useful if we allow function-call like expressions such as [[# %X, pow(10, FOO) +
20]].
>> >
>> >
>> > Alex
>> >
>> >
>> >
>> >>
>> >> Best regards,
>> >>
>> >> Thomas
>> >>
>> >> On Tue, 17 Jul 2018 at 21:59, Alexander Richardson
>> >> <arichardson.kde at gmail.com> wrote:
>> >> >
>> >> >
>> >> >
>> >> > On Tue, 17 Jul 2018 at 10:02 Thomas Preudhomme via
llvm-dev <llvm-dev at lists.llvm.org> wrote:
>> >> >>
>> >> >> To be clear, I do not intend to add support for hex
specifier in the
>> >> >> current patch, I just want to make sure the syntax we
choose is going
>> >> >> to allow it later. My immediate use case is decimal
integer and I
>> >> >> intend to write the code so that it's easy to
extend to more type of
>> >> >> numeric variables and expressions later. This way
we'll only add
>> >> >> specifier that are actually required by actual
testcases.
>> >> >>
>> >> >
>> >> > I also added FileCheck expressions to our fork of LLVM in
order to allow testing both a 128-bit and a 256-bits versions of our CHERI ISA
in a single test case [1].
>> >> > I used [[@EXPR foo * 2 + 1]] for FileCheck expressions
[2]. I'm not particularly happy with this syntax since it is quite verbose
(but then again we don't need it that often so it doesn't really
matter). It also doesn't allow saving the expression result so it needs to
be repeated everywhere. I could probably use [[@EXPR:OUTVAR INVAR + 42]] but I
haven't really had the need for that yet.
>> >> >
>> >> > We currently need the following two features:
>> >> >
>> >> > - Simple arithmetic with multiple operations. Example:
>> >> > `cld $gp, $zero, [[@EXPR 2 * $CAP_SIZE - 8]]($c11)`
>> >> >
>> >> > - Conversion to hex (upper and lower case since not all
tools are consistent here) and to decimal.
>> >> > Example: // READOBJ-NEXT: 0x50
R_MIPS_64/R_MIPS_NONE/R_MIPS_NONE .data 0x[[@EXPR hex($CAP_SIZE * 2)]]
>> >> >
>> >> > Alex
>> >> >
>> >> > [1] For most test cases the simple -DVAR=value flag in
FileCheck is good enough: we have a %cheri_FileCheck lit substitution that
expands to `FileCheck '-D$CAP_SIZE=16/32'` . This works for most IR
level tests since usually the only thing that is different is "align
16" vs "align 32". However, when checking the assembly output or
linker addresses we often need something more complex.
>> >> >
>> >> > [2] A test case showing all the currently supported
expressions can be found here:
<https://github.com/CTSRD-CHERI/llvm/blob/master/test/FileCheck/expressions.txt>
>> >> >
>> >> >
>> >> >>
>> >> >> On Mon, 16 Jul 2018 at 18:39, <paul.robinson at
sony.com> wrote:
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> > > -----Original Message-----
>> >> >> > > From: llvm-dev [mailto:llvm-dev-bounces at
lists.llvm.org] On Behalf Of
>> >> >> > > Thomas Preudhomme via llvm-dev
>> >> >> > > Sent: Monday, July 16, 2018 6:24 AM
>> >> >> > > To: jh7370.2008 at my.bristol.ac.uk
>> >> >> > > Cc: llvm-dev at lists.llvm.org
>> >> >> > > Subject: Re: [llvm-dev] Syntax for
FileCheck numeric variables and
>> >> >> > > expressions
>> >> >> > >
>> >> >> > > Hi James,
>> >> >> > >
>> >> >> > > I like that suggestion very much but I
think keeping the order of the
>> >> >> > > two sides as initially proposed makes more
sense. In printf/scanf the
>> >> >> > > string is first because the primary use of
these functions is to do
>> >> >> > > I/O and so you first specify what you are
going to output/input and
>> >> >> > > then where to capture variables. The
primary objective of FileCheck
>> >> >> > > variables and expressions is to
capture/print them, the specifier is
>> >> >> > > an addon to allow some conversion. Does it
make sense?
>> >> >> >
>> >> >> > My immediate reaction is that I'd rather not
have FileCheck get into
>> >> >> > the business of handling printf specifiers. 
OTOH, while LLVM tools
>> >> >> > do typically print lowercase hex, that's not
guaranteed, and looking
>> >> >> > at the output of other tools can be useful too. 
So, a way to specify
>> >> >> > the case for a hex conversion seems worthwhile.
>> >> >> >
>> >> >> > I had also been thinking in terms of the
trailing colon to distinguish
>> >> >> > definition from use, as James suggested,
that's sort-of consistent
>> >> >> > with the current syntax.
>> >> >> >
>> >> >> > This is starting to make parsing the insides of
[[]] much more involved,
>> >> >> > so you'll want to pay attention to making
that code well-structured and
>> >> >> > readable.
>> >> >> > --paulr
>> >> >> >
>> >> >> > >
>> >> >> > > In the interest of speeding things up I
plan to start implementing
>> >> >> > > this proposal starting tomorrow unless
someone gives some more
>> >> >> > > feedback.
>> >> >> > >
>> >> >> > > Best regards,
>> >> >> > >
>> >> >> > > Thomas
>> >> >> > >
>> >> >> > > On Fri, 13 Jul 2018 at 15:51, James
Henderson
>> >> >> > > <jh7370.2008 at my.bristol.ac.uk>
wrote:
>> >> >> > > >
>> >> >> > > > Hi Thomas,
>> >> >> > > >
>> >> >> > > > In general, I think this is a good
proposal. However, I don't think that
>> >> >> > > using ">" or "<"
to specify base (at least alone) is a good idea, as it
>> >> >> > > might clash with future ideas to do
comparisons etc. I also think it would
>> >> >> > > be nice to have the syntax consistent
between definition and use. My first
>> >> >> > > thought on a reasonable alternative was to
use commas to separate the two
>> >> >> > > parts, so something like:
>> >> >> > > >
>> >> >> > > > [[# VAR, 16:]] to capture a
hexadecimal number (where the spaces are
>> >> >> > > optional). [[# VAR, 16]] to use a variable,
converted to a hexadecimal
>> >> >> > > string. In both cases, the base component
is optional, and defaults to
>> >> >> > > decimal.
>> >> >> > > >
>> >> >> > > > This led me to thing that it might be
better to use something similar to
>> >> >> > > printf style for the latter half, so to
capture a hexadecimal number with
>> >> >> > > a leading "0x" would be:
"0x[[# VAR, %x:]]" and to use it would be "0x[[#
>> >> >> > > VAR, %x]]". Indeed, that would allow
straightforward conversions between
>> >> >> > > formats, so say you defined it by capturing
a decimal integer and using it
>> >> >> > > to match a hexadecimal in upper case, with
leading 0x and 8 digits
>> >> >> > > following the 0x:
>> >> >> > > >
>> >> >> > > > CHECK: [[# VAR, %d:]] # Defines
>> >> >> > > > CHECK: 0x[[# VAR + 1, %8X]] # Uses
>> >> >> > > >
>> >> >> > > > Of course, if we go down that route,
it would probably make more sense
>> >> >> > > to reverse the two sides (e.g. to become
"[[# %d, VAR:]]" to capture a
>> >> >> > > decimal and "[[# %8X, VAR + 1]]"
to use it).
>> >> >> > > >
>> >> >> > > > Regards,
>> >> >> > > >
>> >> >> > > > James
>> >> >> > > >
>> >> >> > > > On 12 July 2018 at 15:34, Thomas
Preudhomme via llvm-dev <llvm-
>> >> >> > > dev at lists.llvm.org> wrote:
>> >> >> > > >>
>> >> >> > > >> Hi all,
>> >> >> > > >>
>> >> >> > > >> I've written a patch to extend
FileCheck to support matching
>> >> >> > > >> arithmetic expressions involving
variable [1] (eg. to match REG+1
>> >> >> > > >> where REG is a variable with a
numeric value). It was suggested to me
>> >> >> > > >> in the review to introduce the
concept of numeric variable and to
>> >> >> > > >> allow for specifying the base the
value are written in.
>> >> >> > > >>
>> >> >> > > >> [1]
https://reviews.llvm.org/D49084
>> >> >> > > >>
>> >> >> > > >> I think the syntax should satisfy
the below requirements:
>> >> >> > > >>
>> >> >> > > >> * based off the [[]] construct
since anything else might overload an
>> >> >> > > >> existing valid syntax (eg. $$ is
supposed to match literally now)
>> >> >> > > >> * consistent with syntax for
expressions using @LINE
>> >> >> > > >> * consistent with using
':' to define regular variable
>> >> >> > > >> * allows to specify base of the
number a numeric variable is being set
>> >> >> > > to
>> >> >> > > >> * allows to specify base of the
result of the numeric expression
>> >> >> > > >>
>> >> >> > > >> I've come up with the
following syntax for which I'd like feedback:
>> >> >> > > >>
>> >> >> > > >> Numeric variable definition:
[[#X<base:]] (eg. [[#ADDR<16:]]) where X
>> >> >> > > >> is the numeric variable being
defined and <base is optional in which
>> >> >> > > >> case base defaults to 10
>> >> >> > > >> Numeric variable use:
[[#X>base]] (eg. [[#ADDR]]>2) where <base is
>> >> >> > > >> optional in which case base
defaults 10
>> >> >> > > >> Numeric expression:
[[exp>base]] (eg. [[#ADDR+2>16]] where expression
>> >> >> > > >> must contain at least one numeric
variable
>> >> >> > > >>
>> >> >> > > >>
>> >> >> > > >> I'm not a big fan of the >
for the output base being inside the
>> >> >> > > >> expression but [[exp]]>base
would match >base literally.
>> >> >> > > >>
>> >> >> > > >> Any suggestions / opinions?
>> >> >> > > >>
>> >> >> > > >> Best regards,
>> >> >> > > >>
>> >> >> > > >> Thomas
>> >> >> > > >>
_______________________________________________
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>> >> >> > > >> llvm-dev at lists.llvm.org
>> >> >> > > >>
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>> >> >> > > >
>> >> >> > > >
>> >> >> > >
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>> >> >> > >
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