[llvm] [AMDGPU] SIInstrInfo: Fix resultDependsOnExec for VOPC instructions (PR #134629)

[Jay Foad via llvm-commits]

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@@ -151,6 +151,9 @@ static bool resultDependsOnExec(const MachineInstr &MI) {
   // Ignore comparisons which are only used masked with exec.
   // This allows some hoisting/sinking of VALU comparisons.
   if (MI.isCompare()) {
+    if (SIInstrInfo::isVOPC(MI))
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jayfoad wrote:

It is really not clear to me why this is correct. The function comment says "Returns true if the scalar result of a VALU instruction depends on exec" - but what does that mean for an instruction with no explicit def?

https://github.com/llvm/llvm-project/pull/134629