[PATCH] D52577: [AMDGPU] Fold copy (copy vgpr)
Stanislav Mekhanoshin via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 26 14:39:03 PDT 2018
rampitec created this revision.
rampitec added a reviewer: kzhuravl.
Herald added subscribers: t-tye, tpr, dstuttard, yaxunl, nhaehnle, wdng, jvesely, arsenm.
This allows to reduce a number of used VGPRs in some cases.
https://reviews.llvm.org/D52577
Files:
lib/Target/AMDGPU/SIFoldOperands.cpp
test/CodeGen/AMDGPU/fold-vgpr-copy.mir
Index: test/CodeGen/AMDGPU/fold-vgpr-copy.mir
===================================================================
--- /dev/null
+++ test/CodeGen/AMDGPU/fold-vgpr-copy.mir
@@ -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
+
+...
Index: lib/Target/AMDGPU/SIFoldOperands.cpp
===================================================================
--- lib/Target/AMDGPU/SIFoldOperands.cpp
+++ lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -477,6 +477,20 @@
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
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