/// Return true if this function can prove that V is never undef value
/// or poison value.
- //
- /// If CtxI and DT are specified this method performs flow-sensitive analysis
- /// and returns true if it is guaranteed to be never undef or poison
- /// immediately before the CtxI.
- bool isGuaranteedNotToBeUndefOrPoison(const Value *V,
- const Instruction *CtxI = nullptr,
- const DominatorTree *DT = nullptr);
+ bool isGuaranteedNotToBeUndefOrPoison(const Value *V);
/// Specific patterns of select instructions we can match.
enum SelectPatternFlavor {
}
/// Given operands for a Freeze, see if we can fold the result.
-static Value *SimplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) {
+static Value *SimplifyFreezeInst(Value *Op0) {
// Use a utility function defined in ValueTracking.
- if (llvm::isGuaranteedNotToBeUndefOrPoison(Op0, Q.CxtI, Q.DT))
+ if (llvm::isGuaranteedNotToBeUndefOrPoison(Op0))
return Op0;
-
// We have room for improvement.
return nullptr;
}
Value *llvm::SimplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) {
- return ::SimplifyFreezeInst(Op0, Q);
+ return ::SimplifyFreezeInst(Op0);
}
/// See if we can compute a simplified version of this instruction.
return llvm::any_of(GuardingBranches, AllUsesGuardedByBranch);
}
-bool llvm::isGuaranteedNotToBeUndefOrPoison(const Value *V,
- const Instruction *CtxI,
- const DominatorTree *DT) {
+bool llvm::isGuaranteedNotToBeUndefOrPoison(const Value *V) {
// If the value is a freeze instruction, then it can never
// be undef or poison.
if (isa<FreezeInst>(V))
return true;
}
- if (!CtxI || !DT)
- return false;
-
- // If V is used as a branch condition before reaching CtxI, V cannot be
- // undef or poison.
- // br V, BB1, BB2
- // BB1:
- // CtxI ; V cannot be undef or poison here
- auto Dominator = DT->getNode(CtxI->getParent())->getIDom();
- while (Dominator) {
- auto *TI = Dominator->getBlock()->getTerminator();
-
- if (auto BI = dyn_cast<BranchInst>(TI)) {
- if (BI->isConditional() && BI->getCondition() == V)
- return true;
- } else if (auto SI = dyn_cast<SwitchInst>(TI)) {
- if (SI->getCondition() == V)
- return true;
- }
-
- Dominator = Dominator->getIDom();
- }
-
return false;
}
%x = freeze i32 10
ret i32 %x
}
-
-define i1 @brcond(i1 %c, i1 %c2) {
-; CHECK-LABEL: @brcond(
-; CHECK-NEXT: br i1 [[C:%.*]], label [[A:%.*]], label [[B:%.*]]
-; CHECK: A:
-; CHECK-NEXT: br i1 [[C2:%.*]], label [[A2:%.*]], label [[B]]
-; CHECK: A2:
-; CHECK-NEXT: ret i1 [[C]]
-; CHECK: B:
-; CHECK-NEXT: ret i1 [[C]]
-;
- br i1 %c, label %A, label %B
-A:
- br i1 %c2, label %A2, label %B
-A2:
- %f1 = freeze i1 %c
- ret i1 %f1
-B:
- %f2 = freeze i1 %c
- ret i1 %f2
-}
-
-define i32 @brcond_switch(i32 %x) {
-; CHECK-LABEL: @brcond_switch(
-; CHECK-NEXT: switch i32 [[X:%.*]], label [[EXIT:%.*]] [
-; CHECK-NEXT: i32 0, label [[A:%.*]]
-; CHECK-NEXT: ]
-; CHECK: A:
-; CHECK-NEXT: ret i32 [[X]]
-; CHECK: EXIT:
-; CHECK-NEXT: ret i32 [[X]]
-;
- switch i32 %x, label %EXIT [ i32 0, label %A ]
-A:
- %fr1 = freeze i32 %x
- ret i32 %fr1
-EXIT:
- %fr2 = freeze i32 %x
- ret i32 %fr2
-}
-
-define i1 @brcond_noopt(i1 %c, i1 %c2) {
-; CHECK-LABEL: @brcond_noopt(
-; CHECK-NEXT: [[F:%.*]] = freeze i1 [[C:%.*]]
-; CHECK-NEXT: call void @f1(i1 [[F]])
-; CHECK-NEXT: call void @f2()
-; CHECK-NEXT: br i1 [[C]], label [[A:%.*]], label [[B:%.*]]
-; CHECK: A:
-; CHECK-NEXT: ret i1 false
-; CHECK: B:
-; CHECK-NEXT: ret i1 true
-;
- %f = freeze i1 %c
- call void @f1(i1 %f) ; cannot optimize i1 %f to %c
- call void @f2() ; .. because if f2() exits, `br %c` cannot be reached
- br i1 %c, label %A, label %B
-A:
- ret i1 0
-B:
- ret i1 1
-}
-declare void @f1(i1)
-declare void @f2()