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[GlobalOpt] Fix the load types when OptimizeGlobalAddressOfMalloc 

Currently, in OptimizeGlobalAddressOfMalloc, the transformation for global loads assumes that they have the same Type. With the support of ConstantExpr (https://reviews.llvm.org/D106589), this may not be true any more (as seen in the test case), and we miss the code to handle this, This is to fix that.

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D107397
This commit is contained in:
Shimin Cui 2021-08-03 19:22:53 -04:00
parent ba2be8deba
commit 2d9759c790
2 changed files with 51 additions and 7 deletions
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14
llvm/lib/Transforms/IPO/GlobalOpt.cpp
View File

@ -967,9 +967,8 @@ OptimizeGlobalAddressOfMalloc(GlobalVariable *GV, CallInst *CI, Type *AllocTy,
}
}
Constant *RepValue = NewGV;
if (NewGV->getType() != GV->getValueType())
RepValue = ConstantExpr::getBitCast(RepValue, GV->getValueType());
SmallPtrSet<Constant *, 1> 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 @@ OptimizeGlobalAddressOfMalloc(GlobalVariable *GV, CallInst *CI, Type *AllocTy,
Use &LoadUse = *LI->use_begin();
ICmpInst *ICI = dyn_cast<ICmpInst>(LoadUse.getUser());
if (!ICI) {
LoadUse = RepValue;
auto *CE = ConstantExpr::getBitCast(NewGV, LI->getType());
RepValues.insert(CE);
LoadUse.set(CE);
continue;
}
@ -1047,9 +1048,8 @@ OptimizeGlobalAddressOfMalloc(GlobalVariable *GV, CallInst *CI, Type *AllocTy,
// 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;
}

44
llvm/test/Transforms/GlobalOpt/2021-08-03-StoreOnceLoadMultiCasts.ll Normal file
View File

@ -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()