Revert "[ValueTracking] Let isGuaranteedNotToBeUndefOrPoison look int…

…o branch conditions of dominating blocks' terminators"

That commit causes SIGSEGV on some simple tests.
This reverts commit 952ad47.

llvm/include/llvm/Analysis/ValueTracking.h

@@ -569,13 +569,7 @@ class Value;
 
   /// 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 {

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -5360,17 +5360,16 @@ Value *llvm::SimplifyCall(CallBase *Call, const SimplifyQuery &Q) {
 }
 
 /// 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.

llvm/lib/Analysis/ValueTracking.cpp

@@ -4525,9 +4525,7 @@ bool llvm::isOverflowIntrinsicNoWrap(const WithOverflowInst *WO,
   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))
@@ -4560,29 +4558,6 @@ bool llvm::isGuaranteedNotToBeUndefOrPoison(const Value *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;
 }
 

llvm/test/Transforms/InstSimplify/freeze.ll

@@ -18,66 +18,3 @@ define i32 @make_const() {
   %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()