[SCEVExpander] Expand UDiv avoiding UB when in seq_min/max. #92177
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -676,7 +676,15 @@ Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) { | |
| SCEV::FlagAnyWrap, /*IsSafeToHoist*/ true); | ||
| } | ||
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| const SCEV *RHSExpr = S->getRHS(); | ||
| Value *RHS = expand(RHSExpr); | ||
| if (SafeUDivMode && | ||
| (!isa<SCEVConstant>(RHSExpr) || SE.isKnownNonZero(RHSExpr))) { | ||
| if (!isa<SCEVConstant>(S->getRHS())) | ||
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| RHS = Builder.CreateFreeze(RHS); | ||
| RHS = Builder.CreateIntrinsic(RHS->getType(), Intrinsic::umax, | ||
| {RHS, ConstantInt::get(RHS->getType(), 1)}); | ||
| } | ||
| return InsertBinop(Instruction::UDiv, LHS, RHS, SCEV::FlagAnyWrap, | ||
| /*IsSafeToHoist*/ SE.isKnownNonZero(S->getRHS())); | ||
| } | ||
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@@ -1371,11 +1379,14 @@ Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) { | |
| Value *SCEVExpander::expandMinMaxExpr(const SCEVNAryExpr *S, | ||
| Intrinsic::ID IntrinID, Twine Name, | ||
| bool IsSequential) { | ||
| bool PrevSafeMode = SafeUDivMode; | ||
| SafeUDivMode |= IsSequential; | ||
| Value *LHS = expand(S->getOperand(S->getNumOperands() - 1)); | ||
| Type *Ty = LHS->getType(); | ||
| if (IsSequential) | ||
| LHS = Builder.CreateFreeze(LHS); | ||
| for (int i = S->getNumOperands() - 2; i >= 0; --i) { | ||
| SafeUDivMode = (IsSequential && i != 0) || PrevSafeMode; | ||
| Value *RHS = expand(S->getOperand(i)); | ||
| if (IsSequential && i != 0) | ||
| RHS = Builder.CreateFreeze(RHS); | ||
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@@ -1390,6 +1401,7 @@ Value *SCEVExpander::expandMinMaxExpr(const SCEVNAryExpr *S, | |
| } | ||
| LHS = Sel; | ||
| } | ||
| SafeUDivMode = PrevSafeMode; | ||
| return LHS; | ||
| } | ||
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Unused prototype.
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Dropped, thanks!