[InstSimplify] Don't simplify a multi-use freeze in simplifyWithOpReplaced

Author: dtcxzyw

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -4312,6 +4312,10 @@ static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
   if (match(I, m_Intrinsic<Intrinsic::is_constant>()))
     return nullptr;
 
+  // Don't simplify a use of a multi-use freeze.
+  if (isa<FreezeInst>(I) && !I->hasOneUse())
+    return nullptr;
+
   // Replace Op with RepOp in instruction operands.
   SmallVector<Value *, 8> NewOps;
   bool AnyReplaced = false;

llvm/test/Transforms/InstCombine/select.ll

@@ -4586,7 +4586,9 @@ define i8 @test_replace_freeze_multiuse(i1 %x, i8 %y) {
 ; CHECK-NEXT:    [[EXT:%.*]] = zext i1 [[X:%.*]] to i8
 ; CHECK-NEXT:    [[SHL:%.*]] = shl nuw i8 [[EXT]], [[Y:%.*]]
 ; CHECK-NEXT:    [[SHL_FR:%.*]] = freeze i8 [[SHL]]
-; CHECK-NEXT:    ret i8 [[SHL_FR]]
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[X]], i8 0, i8 [[SHL_FR]]
+; CHECK-NEXT:    [[ADD:%.*]] = add i8 [[SHL_FR]], [[SEL]]
+; CHECK-NEXT:    ret i8 [[ADD]]
 ;
   %ext = zext i1 %x to i8
   %shl = shl nuw i8 %ext, %y