[PATCH] D52559: [AMDGPU] Divergence driven instruction selection. Shift operations.

[Alexander via Phabricator via llvm-commits]

alex-t added inline comments.


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Comment at: lib/Target/AMDGPU/VOP3Instructions.td:587
+    VOP3e_si <op, !cast<VOP3_Pseudo>(NAME).Pfl> {
+      // Hack to stop printing _e64
+      VOP3_Pseudo ps = !cast<VOP3_Pseudo>(NAME);
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rampitec wrote:
> alex-t wrote:
> > rampitec wrote:
> > > alex-t wrote:
> > > > rampitec wrote:
> > > > > Does it really belong to this patch?
> > > > Sure it does. As soon as I start selecting this _b64  the LIT tests failed because of the odd "_e64" suffix printed by AMDGPUInstrPrinter. It prints it for all with VOP3 flag.
> > > > The flag was not set before this change because the instructions were created in moveToVALU.  
> > > > I filed the bug https://bugs.llvm.org/show_bug.cgi?id=39086 for adding the flag to indicate that the instruction does not have 32bit encoding.
> > > > 
> > > How can it be possible for moveToVALU to create a VOP3 instruction without a VOP3 flag?
> > > VOP3_Pseudo sets VOP3 flag. InstSI copies it into TSFlags. VOP3_Real copies TSFlags from a pseudo.
> > InstSI copies VOP3 to TSFlags and your code checks exactly TSFlags & SIInstrFlags::VOP3
> So the explanation is wrong. It has VOP3 in TSFlags with or without your changes. It is worth nothing where the instruction is created. The suffix was not printed because the control did not even come to the AMDGPUInstPrinter::printVOPDst, and it did not trigger because these instructions did not have VOPDstOperand in the td. Now what you have changed is the operand definition. What you need to fix the problem instead of the hack is to return DstRC back to the RegisterOperand<VReg_64> in the profile.
I did not change the VOP3_Profile.
The reason was in the order of the profiles instantiation:  VOP_PAT_GEN<VOP3_Profile<...>>  VOP_PAT_GEN does not inherit VOP3_Profile let statements. It just inherits types.

The fix is:  VOP3_Profile<VOP_PAT_GEN<...> and to add to VOP3_Profile

 "let NeedPatGen = P.NeedPatGen"





https://reviews.llvm.org/D52559