[llvm] [AMDGPU][MachineVerifier] test failures in SIFoldOperands (PR #166600)

[Abhay Kanhere via llvm-commits]

https://github.com/AbhayKanhere created https://github.com/llvm/llvm-project/pull/166600

After PR:https://github.com/llvm/llvm-project/pull/151421 merged following fails in SIFoldOperands showed up.

LLVM :: CodeGen/AMDGPU/GlobalISel/llvm.amdgcn.mfma.gfx90a.ll
LLVM :: CodeGen/AMDGPU/llvm.amdgcn.mfma.gfx90a.ll
LLVM :: CodeGen/AMDGPU/llvm.amdgcn.mfma.ll
LLVM :: CodeGen/AMDGPU/mfma-loop.ll
LLVM :: CodeGen/AMDGPU/rewrite-vgpr-mfma-to-agpr.ll

In Folding code, if folded operand is register ensure earlyClobber is set.

>From c37f1d1f49111bc2e818de8592270566355bdd90 Mon Sep 17 00:00:00 2001
From: Abhay Kanhere <abhay at kanhere.net>
Date: Wed, 5 Nov 2025 09:51:02 -0800
Subject: [PATCH] [AMDGPU][MachineVerifier] test failures in SIFoldOperands

After PR:https://github.com/llvm/llvm-project/pull/151421 merged
following fails in SIFoldOperands showed up.

LLVM :: CodeGen/AMDGPU/GlobalISel/llvm.amdgcn.mfma.gfx90a.ll
LLVM :: CodeGen/AMDGPU/llvm.amdgcn.mfma.gfx90a.ll
LLVM :: CodeGen/AMDGPU/llvm.amdgcn.mfma.ll
LLVM :: CodeGen/AMDGPU/mfma-loop.ll
LLVM :: CodeGen/AMDGPU/rewrite-vgpr-mfma-to-agpr.ll

In Folding code, if folded operand is register ensure earlyClobber
is set.
---
 llvm/lib/Target/AMDGPU/SIFoldOperands.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
index 6616b30410590..cf9a6f021fd9b 100644
--- a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -689,6 +689,10 @@ bool SIFoldOperandsImpl::updateOperand(FoldCandidate &Fold) const {
     if (!TII->isOperandLegal(*MI, OpNo, &New))
       return false;
 
+    const MCInstrDesc &MCID = MI->getDesc();
+    if (MCID.getOperandConstraint(OpNo, MCOI::EARLY_CLOBBER) != -1) {
+      MI->getOperand(OpNo).setIsEarlyClobber(true);
+    }
     Old.ChangeToImmediate(*ImmVal);
     return true;
   }