llvm dev - Feb 2014 - [LLVMdev] emitting function stub for mips16 floating point patch

I'm rewriting this patch for the stubs to not use outputing of raw text.

Generating the instructions is very straightforward and that part is done.

I'm translating the actual function now.

How do you emit an .ent or .globl from asm printer?
.type ?
.end ??
.section ???

I'm studying the classes now but it should be simple to do so if you 
know, you can save me some time
because this is another maze of llvm data abstraction.

Tia.

Reed






void MipsAsmPrinter::EmitFPCallStub(
   const char* Symbol, const Mips16HardFloatInfo::FuncSignature* 
Signature) {
   OutStreamer.EmitRawText("\t.globl "+ Twine(Symbol));
.........
   OutStreamer.EmitRawText("\t# Stub function to call " +
Twine(RetType) +
                           " " + Twine(Symbol) + " (" +
Twine(Parms) + ")");
OutStreamer.EmitRawText("\t.section\t.mips16.call.fp"+Twine(Symbol)+",\"ax\",
at progbits");
   OutStreamer.EmitRawText(".align 2");
   OutStreamer.EmitRawText(".nomips16");
   OutStreamer.EmitRawText(".nomicromips");
   OutStreamer.EmitRawText("\t.ent\t__call_stub_fp_" + Twine(Symbol));
   OutStreamer.EmitRawText("\t.type\t__call_stub_fp_" + Twine(Symbol)
+
", @function");
   OutStreamer.EmitRawText("\t__call_stub_fp_" + Twine(Symbol) +
":");
   OutStreamer.EmitRawText("\t.size  __call_stub_fp_" + Twine(Symbol)
+
                           ", .-__call_stub_fp_" + Twine(Symbol));
   OutStreamer.EmitRawText("\t.end  __call_stub_fp_" + Twine(Symbol))

On 01/31/2014 03:59 PM, reed kotler wrote:
> I'm rewriting this patch for the stubs to not use outputing of raw
text.
>
> Generating the instructions is very straightforward and that part is 
> done.
>
> I'm translating the actual function now.
>
> How do you emit an .ent or .globl from asm printer?
> .type ?
> .end ??
> .section ???
>
> I'm studying the classes now but it should be simple to do so if you 
> know, you can save me some time
> because this is another maze of llvm data abstraction.
>
> Tia.
>
> Reed
>
>
>
We already have this MIpsTargetStreamer class which seems like a place 
where this could be added.

Given the big storm around any kind of raw text I don't want to add to 
this if this is already something
we are not supposed to be doing.
>
>
>
> void MipsAsmPrinter::EmitFPCallStub(
>   const char* Symbol, const Mips16HardFloatInfo::FuncSignature* 
> Signature) {
>   OutStreamer.EmitRawText("\t.globl "+ Twine(Symbol));
> .........
>   OutStreamer.EmitRawText("\t# Stub function to call " +
Twine(RetType) +
>                           " " + Twine(Symbol) + " (" +
Twine(Parms) +
> ")");
>
OutStreamer.EmitRawText("\t.section\t.mips16.call.fp"+Twine(Symbol)+",\"ax\",
at progbits");
>
>   OutStreamer.EmitRawText(".align 2");
>   OutStreamer.EmitRawText(".nomips16");
>   OutStreamer.EmitRawText(".nomicromips");
>   OutStreamer.EmitRawText("\t.ent\t__call_stub_fp_" +
Twine(Symbol));
>   OutStreamer.EmitRawText("\t.type\t__call_stub_fp_" +
Twine(Symbol) +
> ", @function");
>   OutStreamer.EmitRawText("\t__call_stub_fp_" + Twine(Symbol) +
":");
>   OutStreamer.EmitRawText("\t.size  __call_stub_fp_" +
Twine(Symbol) +
>                           ", .-__call_stub_fp_" + Twine(Symbol));
>   OutStreamer.EmitRawText("\t.end  __call_stub_fp_" +
Twine(Symbol))

Hi Reed,

I think you need to look at:
* MCStreamer::SwitchSection() for .section.
* MipsTargetStreamer::emitDirectiveEnt() for .ent
* MCAsmStreamer::EmitSymbolAttribute() for .globl, and .type

I couldn't find a function for .end. I expect it's there but it's
difficult to grep for because it clashes with iterators.

If there are any directives you need that aren't already supported,
you'll need an emitX function for each directive in each of the MIPS target
streamers. The one in MipsTargetStreamer should be abstract, the one in
MipsAsmTargetStreamer should emit the assembly text, and the one in
MipsELFTargetStreamer should do the appropriate thing in the ELF. For your
purposes you could leave an llvm_unreachable("Not implemented") in the
MipsELFTargetStreamer for now, but it would be great if you could implement that
as well since someone will have to do it for the planned assembler anyway. If
you do implement MipsELFTargetStreamer::emitX(), you will also need to implement
the relevant AsmParser support so that you can test the directive (tests using
llc -filetype=obj are not ok).
See MipsTargetStreamer::emitDirectiveSetMicroMips() for an example.
> -----Original Message-----
> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu]
> On Behalf Of Reed Kotler
> Sent: 01 February 2014 00:04
> To: LLVMdev at cs.uiuc.edu
> Subject: Re: [LLVMdev] emitting function stub for mips16 floating point
patch
> 
> On 01/31/2014 03:59 PM, reed kotler wrote:
> > I'm rewriting this patch for the stubs to not use outputing of raw
text.
> >
> > Generating the instructions is very straightforward and that part is
> > done.
> >
> > I'm translating the actual function now.
> >
> > How do you emit an .ent or .globl from asm printer?
> > .type ?
> > .end ??
> > .section ???
> >
> > I'm studying the classes now but it should be simple to do so if
you
> > know, you can save me some time because this is another maze of llvm
> > data abstraction.
> >
> > Tia.
> >
> > Reed
> >
> >
> >
> We already have this MIpsTargetStreamer class which seems like a place
> where this could be added.
> 
> Given the big storm around any kind of raw text I don't want to add to
this if
> this is already something we are not supposed to be doing.
> 
> >
> >
> >
> > void MipsAsmPrinter::EmitFPCallStub(
> >   const char* Symbol, const Mips16HardFloatInfo::FuncSignature*
> > Signature) {
> >   OutStreamer.EmitRawText("\t.globl "+ Twine(Symbol));
.........
> >   OutStreamer.EmitRawText("\t# Stub function to call " +
Twine(RetType) +
> >                           " " + Twine(Symbol) + "
(" + Twine(Parms) +
> > ")");
> >
OutStreamer.EmitRawText("\t.section\t.mips16.call.fp"+Twine(Symbol)+",
> > \"ax\", at progbits");
> >
> >   OutStreamer.EmitRawText(".align 2");
> >   OutStreamer.EmitRawText(".nomips16");
> >   OutStreamer.EmitRawText(".nomicromips");
> >   OutStreamer.EmitRawText("\t.ent\t__call_stub_fp_" +
Twine(Symbol));
> >   OutStreamer.EmitRawText("\t.type\t__call_stub_fp_" +
Twine(Symbol) +
> > ", @function");
> >   OutStreamer.EmitRawText("\t__call_stub_fp_" +
Twine(Symbol) + ":");
> >   OutStreamer.EmitRawText("\t.size  __call_stub_fp_" +
Twine(Symbol) +
> >                           ", .-__call_stub_fp_" +
Twine(Symbol));
> >   OutStreamer.EmitRawText("\t.end  __call_stub_fp_" +
Twine(Symbol))
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On 31 January 2014 18:59, reed kotler <rkotler at mips.com>
wrote:
> I'm rewriting this patch for the stubs to not use outputing of raw
text.
>
> Generating the instructions is very straightforward and that part is done.
awesome!
> I'm translating the actual function now.
>
> How do you emit an .ent
emitDirectiveEnt in the mips target streamer.
> or .globl
EmitSymbolAttribute with MCSA_Global
> from asm printer?
> .type ?
EmitSymbolAttribute with  MCSA_ELF_Type*
> .end ??
emitDirectiveEnd on the mips target streamer
> .section ???
SwitchSection
> I'm studying the classes now but it should be simple to do so if you
know,
> you can save me some time
> because this is another maze of llvm data abstraction.
The rule of the thumb is that each line in assembly is a method in the
streamer or target streamer.
> Tia.
>
> Reed
Cheers,
Rafael

On 02/04/2014 08:48 AM, Rafael Espíndola wrote:
> On 31 January 2014 18:59, reed kotler <rkotler at mips.com> wrote:
>> I'm rewriting this patch for the stubs to not use outputing of raw
text.
>>
>> Generating the instructions is very straightforward and that part is
done.
> awesome!
>
>> I'm translating the actual function now.
>>
>> How do you emit an .ent
> emitDirectiveEnt in the mips target streamer.
>
>> or .globl
> EmitSymbolAttribute with MCSA_Global
>
>> from asm printer?
>> .type ?
> EmitSymbolAttribute with  MCSA_ELF_Type*
>
>> .end ??
> emitDirectiveEnd on the mips target streamer
>
>> .section ???
> SwitchSection
>
>> I'm studying the classes now but it should be simple to do so if
you know,
>> you can save me some time
>> because this is another maze of llvm data abstraction.
> The rule of the thumb is that each line in assembly is a method in the
> streamer or target streamer.
>
>> Tia.
>>
>> Reed
> Cheers,
> Rafael
THanks.

Your pointers will save some time hunting for the right method.

I have 90% of this done already. Now I know where to look for the 
remaining methods.

When I finish this one patch (almost done, which is for a specific bug), 
I'm planning to start to move all the inline assembly code from
pass Mips16HardFloat to this later place in MipsAsmPrinter. 
Mips16HardFloat pass should shrink to 15% of it's current size. I've
already
started to move the infrastructure to this place in MipsAsmPrinter.

We discussed this a while back and I agreed to eventually do this but it 
was not clear to me at that time exactly where to move it to and it was much
easier for me to do this in the IR pass. Frankly, at that time, I would 
not have at all thought to move it to AsmPrinter :) .
Now I can see where it should go and also understand the gcc mips16 floating
point scheme better (undocumented and complicated at the same time) and 
how it interacts with llvm and such. It makes sense to move it to AsmPrinter
because in reality the stubs are just a sophisticated asm directive that 
must be expanded.

There are a few bizarre asm statements that I hardly understand (copied 
form the gcc mips16 hard float stubs) in some of the yet to be moved stubs.
I may need some additional mc methods to handle those. When I get there 
we can discuss that.

This scheme is handshake between gcc, gas and ld (all undocumented of 
course :)))

Reed



Reed

I'm planning to move most of the inline assembly emission

How is alignment set?


On 02/04/2014 08:48 AM, Rafael Espíndola wrote:
> On 31 January 2014 18:59, reed kotler <rkotler at mips.com> wrote:
>> I'm rewriting this patch for the stubs to not use outputing of raw
text.
>>
>> Generating the instructions is very straightforward and that part is
done.
> awesome!
>
>> I'm translating the actual function now.
>>
>> How do you emit an .ent
> emitDirectiveEnt in the mips target streamer.
>
>> or .globl
> EmitSymbolAttribute with MCSA_Global
>
>> from asm printer?
>> .type ?
> EmitSymbolAttribute with  MCSA_ELF_Type*
>
>> .end ??
> emitDirectiveEnd on the mips target streamer
>
>> .section ???
> SwitchSection
>
>> I'm studying the classes now but it should be simple to do so if
you know,
>> you can save me some time
>> because this is another maze of llvm data abstraction.
> The rule of the thumb is that each line in assembly is a method in the
> streamer or target streamer.
>
>> Tia.
>>
>> Reed
> Cheers,
> Rafael