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[AMDGPU] Fold copy (copy vgpr) 

This allows to reduce a number of used VGPRs in some cases.

Differential Revision: https://reviews.llvm.org/D52577

llvm-svn: 343249
This commit is contained in:
Stanislav Mekhanoshin 2018-09-27 18:55:20 +00:00
parent 670c147d83
commit b080adfc0c
2 changed files with 41 additions and 0 deletions
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14
llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
View File

@ -477,6 +477,20 @@ void SIFoldOperands::foldOperand(
UseMI->setDesc(TII->get(MovOp));
CopiesToReplace.push_back(UseMI);
} else {
if (UseMI->isCopy() && OpToFold.isReg() &&
TargetRegisterInfo::isVirtualRegister(UseMI->getOperand(0).getReg()) &&
TargetRegisterInfo::isVirtualRegister(UseMI->getOperand(1).getReg()) &&
TRI->isVGPR(*MRI, UseMI->getOperand(0).getReg()) &&
TRI->isVGPR(*MRI, UseMI->getOperand(1).getReg()) &&
!UseMI->getOperand(1).getSubReg()) {
UseMI->getOperand(1).setReg(OpToFold.getReg());
UseMI->getOperand(1).setSubReg(OpToFold.getSubReg());
UseMI->getOperand(1).setIsKill(false);
CopiesToReplace.push_back(UseMI);
OpToFold.setIsKill(false);
return;
}
const MCInstrDesc &UseDesc = UseMI->getDesc();
// Don't fold into target independent nodes. Target independent opcodes

27
llvm/test/CodeGen/AMDGPU/fold-vgpr-copy.mir Normal file
View File

@ -0,0 +1,27 @@
# RUN: llc -march=amdgcn -mcpu=gfx900 -run-pass=si-fold-operands,dead-mi-elimination %s -o - | FileCheck -check-prefix=GCN %s
# GCN-LABEL: name: fold_vgpr_copy
# GCN: %0:vreg_64 = IMPLICIT_DEF
# GCN-NEXT: %4:vgpr_32 = IMPLICIT_DEF
# GCN-NEXT: %3:vgpr_32 = IMPLICIT_DEF
# GCN-NEXT: DS_WRITE2_B32_gfx9 %0.sub0, killed %4, killed %3, 0, 1, 0, implicit $exec
---
name: fold_vgpr_copy
registers:
- { id: 0, class: vreg_64 }
- { id: 1, class: vgpr_32 }
- { id: 2, class: vgpr_32 }
- { id: 3, class: vgpr_32 }
- { id: 4, class: vgpr_32 }
body: |
bb.0:
%0:vreg_64 = IMPLICIT_DEF
%4 = IMPLICIT_DEF
%3 = IMPLICIT_DEF
%1:vgpr_32 = COPY %0.sub0
%2:vgpr_32 = COPY %1
DS_WRITE2_B32_gfx9 %2, killed %4, killed %3, 0, 1, 0, implicit $exec
...