Displaying 20 results from an estimated 8000 matches similar to: "Condition removed? Difference between LLVM and GCC on a small testcase"
2018 Dec 04
2
[Unsafe-fp-math] Merge attribute for inlining
Hal,
Thanks for the reply. I am trying to understand the underlying concern. That means the inlining of a callee without unsafe-fp-math attribute set will block the unsafe optimization in its caller, right?
Thanks,
Yan
From: Finkel, Hal J. [mailto:hfinkel at anl.gov]
Sent: Tuesday, December 4, 2018 11:34 AM
To: Yan Luo <yan.luo2 at synopsys.com>; llvm-dev at lists.llvm.org
Subject: Re:
2018 Dec 04
2
[Unsafe-fp-math] Merge attribute for inlining
Hello dev,
I have a question about unsafe-fp-math function attribute. Currently LLVM merges this attribute for inlining with logical AND. That means if caller has this attribute set but callee has not, LLVM will reset this attribute on caller. But shouldn't we respect this attribute on caller? If caller wants to perform unsafe fp operation, any code that gets inlined should be allowed to do
2018 Mar 20
1
Remap values in PromotedFloats
Hello Dev,
I noticed that in the function DAGTypeLegalizer::ExpungeNode we don't remap values in PromotedFloats. Any reason for this? Or it's just a bug?
Regards,
Yan
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2007 Apr 30
0
[LLVMdev] Boostrap Failure -- Expected Differences?
On Apr 27, 2007, at 3:50 PM, David Greene wrote:
> The saga continues.
>
> I've been tracking the interface changes and merging them with
> the refactoring work I'm doing. I got as far as building stage3
> of llvm-gcc but the object files from stage2 and stage3 differ:
>
>
> warning: ./cc1-checksum.o differs
> warning: ./cc1plus-checksum.o differs
>
>
2005 Feb 22
0
[LLVMdev] Area for improvement
On Mon, 21 Feb 2005, Jeff Cohen wrote:
> Sorry, I thought I was running selection dag isel but I screwed up when
> trying out the really big array. You're right, it does clean it up except
> for the multiplication.
>
> So LoopStrengthReduce is not ready for prime time and doesn't actually get
> used?
I don't know what the status of it is. You could try it out,
2005 Feb 22
2
[LLVMdev] Area for improvement
Sorry, I thought I was running selection dag isel but I screwed up when
trying out the really big array. You're right, it does clean it up
except for the multiplication.
So LoopStrengthReduce is not ready for prime time and doesn't actually
get used?
I might consider whipping it into shape. Does it still have to handle
getelementptr in its full generality?
Chris Lattner wrote:
2014 Jul 13
2
[LLVMdev] IMUL x86 instruction
Hi,
The x86 CPU IMUL instruction has forms such as:
IMUL reg
EDX:EAX ← EAX ∗ reg
reg, EAX and EDX are 32bit registers.
How can I represent this sort of instruction in LLVM IR ?
It is really a 32bit * 32 bit = 64 bit, but no LLVM IR exists to do that.
Or, a similar question:
What LLVM IR would produce this IMUL instruction form?
For context, I am writing a x86 to LLVM IR decompiler, so wish to
2020 Jan 07
0
locking warnings in drm/virtio code
Hi!
My development VM (KVM guest, virtio graphics) is throwing warnings
when I start up X while running a build from Linus' tree with lockdep
turned on. I tried to bisect it, and it looks like at least the
"suspicious RCU usage" one started triggering in commit
889165ad6190556ffe4a8fa6b0e486f1c25589d8 ("drm/virtio: pass gem
reservation object to ttm init").
Slightly
2018 Dec 01
2
Where's the optimiser gone? (part 5.c): missed tail calls, and more...
Compile the following functions with "-O3 -target i386-win32"
(see <https://godbolt.org/z/exmjWY>):
__int64 __fastcall div(__int64 foo, __int64 bar)
{
return foo / bar;
}
On the left the generated code; on the right the expected,
properly optimised code:
push dword ptr [esp + 16] |
push dword ptr [esp + 16] |
push dword ptr [esp + 16] |
2016 Nov 22
2
Conditional jump or move depends on uninitialised value(s)
Just want to emphasize that on x86-64 and using Valgrind:
LLVM compiled with LLVM gets 360 unexpected test fails
LLVM compiled with GCC gets 22 unexpected test fails
Of course I don't know how many of these are caused by this bitfield
speculation issue.
John
On 11/21/2016 10:48 PM, regehr via llvm-dev wrote:
> Alright, here's what seems to be happening...
>
> The testcase
2020 Nov 05
0
[EXTERNAL] [llvm-mc] FreeBSD kernel module performance impact when upgrading clang
> You used -noinhibit-exec to ignore the diagnostic, which is usually a bad thing.
I certainly agree with that.
The point I was trying to make in my original email is that, specifically for kernel objects, this diagnostic is incorrect. R_X86_64_PC32 can be used safely against the symbol foo in that specific context, and should be possible without ignoring diagnostics. I wondered if there
2010 Feb 01
5
regular expression submatch?
What is the simplest way to extract a matched subexpression?
Eg. in perl you can do
"hello world" =~ m/hello (.*)/
which would return 1(true) and set $1 to the matched subexpression "world".
--
View this message in context: http://n4.nabble.com/regular-expression-submatch-tp1459146p1459146.html
Sent from the R help mailing list archive at Nabble.com.
2005 Feb 22
0
[LLVMdev] Area for improvement
On Mon, 21 Feb 2005, Jeff Cohen wrote:
> I noticed that fourinarow is one of the programs in which LLVM is much slower
> than GCC, so I decided to take a look and see why that is so. The program
> has many loops that look like this:
>
> #define ROWS 6
> #define COLS 7
>
> void init_board(char b[COLS][ROWS+1])
> {
> int i,j;
>
> for
2015 Dec 17
2
llvm-3.6 MCAsmParser x64 Error "invalid operand for instruction" when msb set
Hello,
I am experiencing problems, when trying to assemble these two x86-64 Opcodes
"add r64, imm32"
"imul r64, r64, imm32"
When having the most significant bit set for imm32, for example:
"add rax, 0x80000000", "add rax, 0xffffffff", ...
"imul rbx, rsi, 0x80000000", "imul rbx, rsi, 0xffffffff", ...
The Error Message I receive is the
2010 Mar 22
6
[LLVMdev] Summer of Code ideas
Hi,
I intend to participate in Google's Summer of Code this year, so I'd
like to bounce another idea around to see what you guys think. (I posted
a similar message to cfe-dev just now.) Be warned: this will shock you.
It may even horrify you.
1. Implement a 16-bit x86 backend. (*Chris recoils in horror*) Yeah, I
know 16-bit x86 is dead, but I find it interesting for historical
purposes
2013 Jun 28
3
[LLVMdev] Hi, people, I propose to move Debug and Object File related headers out of Support
For example,
ELF.h MachO.h and COFF.h
should moved into Object directory with new name.
and Dwarf.h should moved into DebugInfo directory.
2013/6/29 Eric Christopher <echristo at gmail.com>:
> Where would you like to move them?
>
> -eric
>
> On Fri, Jun 28, 2013 at 10:38 AM, 罗勇刚(Yonggang Luo)
> <luoyonggang at gmail.com> wrote:
>> From my point of view, the
2010 Apr 14
3
[LLVMdev] indirect jumps
Hi,
What kind of C/C++ high level code can generate a computed jump, such as:
jmpq *%r14
or
jmpq *(%r14,%rbx,8)
?
I imagine that any calls (including virtual) would use something like 'call *%r14',
and the above jumps are mostly from 'switch' statements.
Is this correct?
Anything else?
Thank you,
Dan
2017 Sep 29
2
HiPE calling convention
Hi all
I saw presentation http://www.softlab.ntua.gr/~gtsiour/files/erllvm_pres-20111107.pdf
and I have couple question to the HiPE calling convention. I am trying to enable HiPE call for Rust compiler.
That presentation mentioned that:
Virtual registers with “special” use, pinned to hardware registers
(unallocatable).
VM Register AMD64 Register
Native stack pointer %nsp
Heap
2012 Nov 29
0
[LLVMdev] radr://12777299, "potential pthread/eh bug exposed by libsanitizer"
I debugged this a bit and it seems the mach_override patching of __cxa_throw is bogus. The start of that function is patched to jump to garbage.
Breakpoint 1, 0x0000000100001c19 in main ()
(gdb) display/i $pc
2: x/i $pc 0x100001c19 <main+318>: callq 0x100016386 <dyld_stub___cxa_throw>
(gdb) si
0x0000000100016386 in dyld_stub___cxa_throw ()
2: x/i $pc 0x100016386
2013 Jun 28
3
[LLVMdev] Hi, people, I propose to move Debug and Object File related headers out of Support
>From my point of view, the Support library should be more pure. And
should not contains
too much LLVM-related APIs and defines,
--
此致
礼
罗勇刚
Yours
sincerely,
Yonggang Luo