[dragonegg] r187105 - Try to update to set the no-frame-pointer-elim-non-leaf attribute as a function attribute instead of target option.

[Bill Wendling]

On Jul 25, 2013, at 9:35 AM, David Blaikie <dblaikie at gmail.com> wrote:

> On Wed, Jul 24, 2013 at 11:20 PM, Bill Wendling <isanbard at gmail.com> wrote:
>> Author: void
>> Date: Thu Jul 25 01:20:06 2013
>> New Revision: 187105
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=187105&view=rev
>> Log:
>> Try to update to set the no-frame-pointer-elim-non-leaf attribute as a function attribute instead of target option.
>> 
>> Modified:
>>    dragonegg/trunk/src/Backend.cpp
>>    dragonegg/trunk/src/Convert.cpp
>> 
>> Modified: dragonegg/trunk/src/Backend.cpp
>> URL: http://llvm.org/viewvc/llvm-project/dragonegg/trunk/src/Backend.cpp?rev=187105&r1=187104&r2=187105&view=diff
>> ==============================================================================
>> --- dragonegg/trunk/src/Backend.cpp (original)
>> +++ dragonegg/trunk/src/Backend.cpp Thu Jul 25 01:20:06 2013
>> @@ -484,11 +484,9 @@ static void CreateTargetMachine(const st
>>   if (flag_omit_frame_pointer) {
>>     // Eliminate frame pointers everywhere.
>>     Options.NoFramePointerElim = false;
>> -    Options.NoFramePointerElimNonLeaf = false;
>>   } else {
>>     // Keep frame pointers everywhere.
>>     Options.NoFramePointerElim = true;
>> -    Options.NoFramePointerElimNonLeaf = true;
>>   }
>>   // If a target has an option to eliminate frame pointers in leaf functions
>>   // only then it should set
>> 
>> Modified: dragonegg/trunk/src/Convert.cpp
>> URL: http://llvm.org/viewvc/llvm-project/dragonegg/trunk/src/Convert.cpp?rev=187105&r1=187104&r2=187105&view=diff
>> ==============================================================================
>> --- dragonegg/trunk/src/Convert.cpp (original)
>> +++ dragonegg/trunk/src/Convert.cpp Thu Jul 25 01:20:06 2013
>> @@ -1034,6 +1034,14 @@ void TreeToLLVM::StartFunctionBody() {
>>   if (lookup_attribute("naked", DECL_ATTRIBUTES(FnDecl)))
>>     Fn->addFnAttr(Attribute::Naked);
>> 
>> +  if (flag_omit_frame_pointer) {
>> +    // Eliminate frame pointers everywhere.
>> +    Fn->addFnAttr("no-frame-pointer-elim-non-leaf", "false");
> 
> Curious choice to do this with if (x) { addFnAttribute } else {
> addFnAttribute } here whereas to use the conditional operator in the
> Clang change for the same.

The clang change was a bit more involved than just a regular if-then. But it doesn't really make much difference.


> As I mentioned there, presumably we want a
> simple bool->StringRef (if we don't already) & just
> Fn->addFnAttr("no-frame-pointer-elim-non-leaf",
> ToString(!flag_omit_frame_pointer))
> 
I suppose that might be useful. But it's low on my priority list right now. :-(

> Speaking of which:
> 
> If the flag has to be present anyway, should we avoid the negative in
> it & just name it "frame-pointer-slim-non-leaf"?
> 

It might be nice to do that. But it will involve changing how it's used throughout the code...

-bw