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[LoopRotate] Use poison instead of undef as placeholder #119135

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Merged
merged 1 commit into from
Dec 10, 2024
Merged

[LoopRotate] Use poison instead of undef as placeholder #119135

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8 changes: 4 additions & 4 deletions llvm/lib/Transforms/Utils/LoopRotationUtils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -171,14 +171,14 @@ static void RewriteUsesOfClonedInstructions(BasicBlock *OrigHeader,
// Users in the OrigPreHeader need to use the value to which the
// original definitions are mapped and anything else can be handled by
// the SSAUpdater. To avoid adding PHINodes, check if the value is
// available in UserBB, if not substitute undef.
// available in UserBB, if not substitute poison.
Value *NewVal;
if (UserBB == OrigPreheader)
NewVal = OrigPreHeaderVal;
else if (SSA.HasValueForBlock(UserBB))
NewVal = SSA.GetValueInMiddleOfBlock(UserBB);
else
NewVal = UndefValue::get(OrigHeaderVal->getType());
NewVal = PoisonValue::get(OrigHeaderVal->getType());
DbgValue->replaceVariableLocationOp(OrigHeaderVal, NewVal);
}

Expand All @@ -194,14 +194,14 @@ static void RewriteUsesOfClonedInstructions(BasicBlock *OrigHeader,
// Users in the OrigPreHeader need to use the value to which the
// original definitions are mapped and anything else can be handled by
// the SSAUpdater. To avoid adding PHINodes, check if the value is
// available in UserBB, if not substitute undef.
// available in UserBB, if not substitute poison.
Value *NewVal;
if (UserBB == OrigPreheader)
NewVal = OrigPreHeaderVal;
else if (SSA.HasValueForBlock(UserBB))
NewVal = SSA.GetValueInMiddleOfBlock(UserBB);
else
NewVal = UndefValue::get(OrigHeaderVal->getType());
NewVal = PoisonValue::get(OrigHeaderVal->getType());
DVR->replaceVariableLocationOp(OrigHeaderVal, NewVal);
}
}
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6 changes: 3 additions & 3 deletions llvm/test/Transforms/LoopRotate/dbgvalue.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -113,7 +113,7 @@ return: ; preds = %if.end

; Check that the dbg.values move up to being immediately below the PHIs,
; using their Values. However once we exit the loop, the x and y values
; become irrelevant and undef, only z gets an LCSSA PHI to preserve it.
; become irrelevant and poison, only z gets an LCSSA PHI to preserve it.
;
; Note that while the icmp is initially undominated by any dbg.value and thus
; shouldn't get a variable location, the first iteration is peeled off into the
Expand All @@ -138,8 +138,8 @@ define i32 @tak2(i32 %x, i32 %y, i32 %z) nounwind ssp !dbg !21 {
; CHECK: tail call i32 @tak(i32
; CHECK: if.end:
; CHECK-NEXT: z.tr.lcssa = phi i32
; CHECK-NEXT: #dbg_value(i32 undef
; CHECK-NEXT: #dbg_value(i32 undef
; CHECK-NEXT: #dbg_value(i32 poison
; CHECK-NEXT: #dbg_value(i32 poison
; CHECK-NEXT: #dbg_value(i32 %z.tr.lcssa
entry:
br label %tailrecurse
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