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[GlobalISel] Make sure G_ASSERT_ZEXT's src ends up with the same rc as dst

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When replacing the dst reg with the src reg, we need to make sure that we
propagate the dst reg's register class through to the src.

Otherwise, we aren't meeting the requirements for G_ASSERT_ZEXT, and so the
verifier will fail.

Differential Revision: https://reviews.llvm.org/D95708
This commit is contained in:
Jessica Paquette 2021-01-29 15:33:23 -08:00
parent 136420859e
commit 36e5b06d50
2 changed files with 34 additions and 0 deletions
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10
lib/CodeGen/GlobalISel/InstructionSelect.cpp
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@ -137,6 +137,16 @@ bool InstructionSelect::runOnMachineFunction(MachineFunction &MF) {
if (isPreISelGenericOptimizationHint(MI.getOpcode())) {
Register DstReg = MI.getOperand(0).getReg();
Register SrcReg = MI.getOperand(1).getReg();
// At this point, the destination register class of the hint may have
// been decided.
//
// Propagate that through to the source register.
const TargetRegisterClass *DstRC = MRI.getRegClassOrNull(DstReg);
if (DstRC)
MRI.setRegClass(SrcReg, DstRC);
assert(canReplaceReg(DstReg, SrcReg, MRI) &&
"Must be able to replace dst with src!");
MI.eraseFromParent();
MRI.replaceRegWith(DstReg, SrcReg);
continue;

24
test/CodeGen/AArch64/GlobalISel/select-hint.mir
View File

@ -62,3 +62,27 @@ body: |
%copy_assert_zext:fpr(s32) = G_ASSERT_ZEXT %copy, 16
$w1 = COPY %copy_assert_zext(s32)
RET_ReallyLR implicit $w1
...
---
name: assert_zext_decided_dst_class
legalized: true
regBankSelected: true
tracksRegLiveness: true
body: |
bb.0:
liveins: $w0, $w1, $w2
; Users of G_ASSERT_ZEXT may end up deciding the destination register class.
; Make sure that the source register class is constrained.
; CHECK-LABEL: name: assert_zext_decided_dst_class
; CHECK: liveins: $w0, $w1, $w2
; CHECK: %copy_with_rc:gpr32sp = COPY $w2
; CHECK: $w1 = COPY %copy_with_rc
; CHECK: RET_ReallyLR implicit $w1
%copy:gpr(s32) = COPY $w0
%copy_assert_zext:gpr(s32) = G_ASSERT_ZEXT %copy, 16
%copy_with_rc:gpr32sp(s32) = COPY $w2
$w1 = COPY %copy_with_rc(s32)
RET_ReallyLR implicit $w1