Index: llvm/lib/Transforms/IPO/GlobalOpt.cpp =================================================================== --- llvm/lib/Transforms/IPO/GlobalOpt.cpp +++ llvm/lib/Transforms/IPO/GlobalOpt.cpp @@ -967,9 +967,8 @@ } } - Constant *RepValue = NewGV; - if (NewGV->getType() != GV->getValueType()) - RepValue = ConstantExpr::getBitCast(RepValue, GV->getValueType()); + SmallPtrSet RepValues; + RepValues.insert(NewGV); // If there is a comparison against null, we will insert a global bool to // keep track of whether the global was initialized yet or not. @@ -1001,7 +1000,9 @@ Use &LoadUse = *LI->use_begin(); ICmpInst *ICI = dyn_cast(LoadUse.getUser()); if (!ICI) { - LoadUse = RepValue; + auto *CE = ConstantExpr::getBitCast(NewGV, LI->getType()); + RepValues.insert(CE); + LoadUse.set(CE); continue; } @@ -1047,9 +1048,8 @@ // To further other optimizations, loop over all users of NewGV and try to // constant prop them. This will promote GEP instructions with constant // indices into GEP constant-exprs, which will allow global-opt to hack on it. - ConstantPropUsersOf(NewGV, DL, TLI); - if (RepValue != NewGV) - ConstantPropUsersOf(RepValue, DL, TLI); + for (auto *CE : RepValues) + ConstantPropUsersOf(CE, DL, TLI); return NewGV; } Index: llvm/test/Transforms/GlobalOpt/2021-08-03-StoreOnceLoadMultiCasts.ll =================================================================== --- /dev/null +++ llvm/test/Transforms/GlobalOpt/2021-08-03-StoreOnceLoadMultiCasts.ll @@ -0,0 +1,44 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py +; RUN: opt -globalopt -S < %s | FileCheck %s +; RUN: opt -passes=globalopt -S < %s | FileCheck %s + +@g = internal global i32* null, align 8 + +define signext i32 @f() local_unnamed_addr { +; CHECK-LABEL: @f( +; CHECK-NEXT: entry: +; CHECK-NEXT: call void @f1() +; CHECK-NEXT: store i32 1, i32* @g.body, align 4 +; CHECK-NEXT: call void @f1() +; CHECK-NEXT: store i8 2, i8* bitcast (i32* @g.body to i8*), align 4 +; CHECK-NEXT: ret i32 1 +; +entry: + %call = call i8* @malloc(i64 4) + %b = bitcast i8* %call to i32* + store i32* %b, i32** @g, align 8 + call void @f1() + %0 = load i32*, i32** @g, align 8 + store i32 1, i32* %0, align 4 + call void @f1() + %1 = load i8*, i8** bitcast (i32** @g to i8**), align 8 + store i8 2, i8* %1, align 4 + ret i32 1 +} + +define signext i32 @main() { +; CHECK-LABEL: @main( +; CHECK-NEXT: entry: +; CHECK-NEXT: [[CALL:%.*]] = call signext i32 @f() +; CHECK-NEXT: [[TMP0:%.*]] = load i32, i32* @g.body, align 4 +; CHECK-NEXT: ret i32 [[TMP0]] +; +entry: + %call = call signext i32 @f() + %0 = load i32*, i32** @g, align 8 + %1 = load i32, i32* %0, align 4 + ret i32 %1 +} + +declare noalias align 16 i8* @malloc(i64) +declare void @f1()