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[AMDGPU] Avoid an illegal operand in si-shrink-instructions

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Before the patch it was possible to trigger a constant bus
violation when folding immediates into a shrunk instruction.

The patch adds a check to enforce the legality of the new operand.

Differential Revision: https://reviews.llvm.org/D95527
This commit is contained in:
Piotr Sobczak 2021-01-27 16:02:49 +01:00
parent 2c90b2760d
commit 2a9ac6c11e
2 changed files with 36 additions and 11 deletions
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24
lib/Target/AMDGPU/SIShrinkInstructions.cpp
View File

@ -75,17 +75,19 @@ static bool foldImmediates(MachineInstr &MI, const SIInstrInfo *TII,
MachineOperand &MovSrc = Def->getOperand(1);
bool ConstantFolded = false;
if (MovSrc.isImm() && (isInt<32>(MovSrc.getImm()) ||
isUInt<32>(MovSrc.getImm()))) {
Src0.ChangeToImmediate(MovSrc.getImm());
ConstantFolded = true;
} else if (MovSrc.isFI()) {
Src0.ChangeToFrameIndex(MovSrc.getIndex());
ConstantFolded = true;
} else if (MovSrc.isGlobal()) {
Src0.ChangeToGA(MovSrc.getGlobal(), MovSrc.getOffset(),
MovSrc.getTargetFlags());
ConstantFolded = true;
if (TII->isOperandLegal(MI, Src0Idx, &MovSrc)) {
if (MovSrc.isImm() &&
(isInt<32>(MovSrc.getImm()) || isUInt<32>(MovSrc.getImm()))) {
Src0.ChangeToImmediate(MovSrc.getImm());
ConstantFolded = true;
} else if (MovSrc.isFI()) {
Src0.ChangeToFrameIndex(MovSrc.getIndex());
ConstantFolded = true;
} else if (MovSrc.isGlobal()) {
Src0.ChangeToGA(MovSrc.getGlobal(), MovSrc.getOffset(),
MovSrc.getTargetFlags());
ConstantFolded = true;
}
}
if (ConstantFolded) {

23
test/CodeGen/AMDGPU/shrink-instructions-illegal-fold.mir Normal file
View File

@ -0,0 +1,23 @@
# RUN: llc -march=amdgcn -mcpu=gfx900 -run-pass=si-shrink-instructions --verify-machineinstrs %s -o - | FileCheck %s
# Make sure immediate folding into V_CNDMASK respects constant bus restrictions.
---
name: shrink_cndmask_illegal_imm_folding
tracksRegLiveness: true
body: |
bb.0:
liveins: $vgpr0, $vgpr1
; CHECK-LABEL: name: shrink_cndmask_illegal_imm_folding
; CHECK: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
; CHECK: [[MOV:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 32768, implicit $exec
; CHECK: V_CMP_EQ_U32_e32 0, [[COPY]], implicit-def $vcc, implicit $exec
; CHECK: V_CNDMASK_B32_e32 [[MOV]], killed [[COPY]], implicit $vcc, implicit $exec
%0:vgpr_32 = COPY $vgpr0
%1:vgpr_32 = V_MOV_B32_e32 32768, implicit $exec
V_CMP_EQ_U32_e32 0, %0:vgpr_32, implicit-def $vcc, implicit $exec
%2:vgpr_32 = V_CNDMASK_B32_e64 0, %1:vgpr_32, 0, killed %0:vgpr_32, $vcc, implicit $exec
S_NOP 0
...