[llvm] [AMDGPU][CodeGen] Fold immediates in src1 operands of V_MAD/MAC/FMA/FMAC. (PR #68002)

[Jay Foad via llvm-commits]

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@@ -3250,9 +3250,12 @@ bool SIInstrInfo::FoldImmediate(MachineInstr &UseMI, MachineInstr &DefMI,
     MachineOperand *Src2 = getNamedOperand(UseMI, AMDGPU::OpName::src2);
 
     // Multiplied part is the constant: Use v_madmk_{f16, f32}.
-    // We should only expect these to be on src0 due to canonicalization.
-    if (Src0->isReg() && Src0->getReg() == Reg) {
-      if (!Src1->isReg() || RI.isSGPRClass(MRI->getRegClass(Src1->getReg())))
+    if ((Src0->isReg() && Src0->getReg() == Reg) ||
+        (Src1->isReg() && Src1->getReg() == Reg)) {
+      MachineOperand *RegSrc =
+          Src1->isReg() && Src1->getReg() == Reg ? Src0 : Src1;
+      if (!RegSrc->isReg() ||
+          RI.isSGPRClass(MRI->getRegClass(RegSrc->getReg())))
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jayfoad wrote:

Maybe I have misunderstood then. I'll take a fresh look tomorrow.

https://github.com/llvm/llvm-project/pull/68002