[ValueTracking] Fix incorrect handling of canCreateUndefOrPoison

[aqjune]

Summary

.. in isGuaranteedNotToBeUndefOrPoison.

This caused early exit of isGuaranteedNotToBeUndefOrPoison, making it return
imprecise result.

[nikic]

LGTM

llvm/lib/Analysis/ValueTracking.cpp

 //===- ValueTracking.cpp - Walk computations to compute properties --------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
if (auto *Opr = dyn_cast<Operator>(V)) {
     if (isa<FreezeInst>(V))
       return true;
 
     if (const auto *CB = dyn_cast<CallBase>(V)) {
       if (CB->hasRetAttr(Attribute::NoUndef))
         return true;
     }
 
-    if (canCreateUndefOrPoison(Opr))
-      return false;
-
-    if (all_of(Opr->operands(), OpCheck))
+    if (!canCreateUndefOrPoison(Opr) && all_of(Opr->operands(), OpCheck))
       return true;
   }
 
   if (auto *I = dyn_cast<Instruction>(V)) {
     if (programUndefinedIfPoison(I) && I->getType()->isIntegerTy(1))
       // Note: once we have an agreement that poison is a value-wise concept,
       // we can remove the isIntegerTy(1) constraint.
       return true;

llvm/test/Transforms/InstSimplify/freeze.ll

 A:
   %fr1 = freeze i32 %x
   ret i32 %fr1
 EXIT:
   %fr2 = freeze i32 %x
   ret i32 %fr2
 }
 
+declare i32 @any_num()
+
+define i32 @brcond_call() {
+; CHECK-LABEL: @brcond_call(
+; CHECK-NEXT:    [[X:%.*]] = call i32 @any_num()
+; CHECK-NEXT:    switch i32 [[X]], label [[EXIT:%.*]] [
+; CHECK-NEXT:    ]
+; CHECK:       EXIT:
+; CHECK-NEXT:    ret i32 [[X]]
+;
+  %x = call i32 @any_num()
+  switch i32 %x, label %EXIT []
+EXIT:
+  %y = freeze i32 %x
+  ret i32 %y
+}
+
 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