[SelectionDAG] Resolve TODO: Use signedAddMayOverflow #85586
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@llvm/pr-subscribers-llvm-selectiondag Author: AtariDreams (AtariDreams) ChangesThis will result in more accurate results. Full diff: https://github.com/llvm/llvm-project/pull/85586.diff 1 Files Affected:
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 2670f48aebcff5..831fef27e5410c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4125,8 +4125,13 @@ SelectionDAG::computeOverflowForSignedAdd(SDValue N0, SDValue N1) const {
if (ComputeNumSignBits(N0) > 1 && ComputeNumSignBits(N1) > 1)
return OFK_Never;
- // TODO: Add ConstantRange::signedAddMayOverflow handling.
- return OFK_Sometime;
+ KnownBits N0Known = computeKnownBits(N0);
+ KnownBits N1Known = computeKnownBits(N1);
+
+ ConstantRange N0Range = ConstantRange::fromKnownBits(N0Known, false);
+ ConstantRange N1Range = ConstantRange::fromKnownBits(N1Known, false);
+
+ return mapOverflowResult(N0Range.signedAddMayOverflow(N1Range));
}
SelectionDAG::OverflowKind
|
This will result in more accurate results.
arsenm
reviewed
Mar 18, 2024
| // TODO: Add ConstantRange::signedAddMayOverflow handling. | ||
| return OFK_Sometime; | ||
| KnownBits N0Known = computeKnownBits(N0); | ||
| KnownBits N1Known = computeKnownBits(N1); |
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can early exit if first query didn't report anything useful
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This will result in more accurate results.