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PeepholeOpt: Remove check for reg_sequence def of subregister #124512

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Merged
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Jan 30, 2025
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PeepholeOpt: Remove check for reg_sequence def of subregister #124512

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17 changes: 1 addition & 16 deletions llvm/lib/CodeGen/PeepholeOptimizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1956,22 +1956,7 @@ ValueTrackerResult ValueTracker::getNextSourceFromRegSequence() {
assert((Def->isRegSequence() || Def->isRegSequenceLike()) &&
"Invalid definition");

if (Def->getOperand(DefIdx).getSubReg())
// If we are composing subregs, bail out.
// The case we are checking is Def.<subreg> = REG_SEQUENCE.
// This should almost never happen as the SSA property is tracked at
// the register level (as opposed to the subreg level).
// I.e.,
// Def.sub0 =
// Def.sub1 =
// is a valid SSA representation for Def.sub0 and Def.sub1, but not for
// Def. Thus, it must not be generated.
// However, some code could theoretically generates a single
// Def.sub0 (i.e, not defining the other subregs) and we would
// have this case.
// If we can ascertain (or force) that this never happens, we could
// turn that into an assertion.
return ValueTrackerResult();
assert(!Def->getOperand(DefIdx).getSubReg() && "illegal subregister def");

SmallVector<RegSubRegPairAndIdx, 8> RegSeqInputRegs;
if (!TII->getRegSequenceInputs(*Def, DefIdx, RegSeqInputRegs))
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