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[GlobalOpt] Don't replace alias with aliasee if aliasee is interposable 

Both the alias and aliasee linkage are important.

PR27866 provides some background.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D99629
This commit is contained in:
Arthur Eubanks 2021-04-20 11:02:57 -07:00
parent c0bf5929ee
commit 16ff1a7023
2 changed files with 16 additions and 2 deletions
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6
llvm/lib/Transforms/IPO/GlobalOpt.cpp
View File

@ -2944,9 +2944,11 @@ OptimizeGlobalAliases(Module &M,
Constant *Aliasee = J->getAliasee();
GlobalValue *Target = dyn_cast<GlobalValue>(Aliasee->stripPointerCasts());
// We can't trivially replace the alias with the aliasee if the aliasee is
// non-trivial in some way.
// non-trivial in some way. We also can't replace the alias with the aliasee
// if the aliasee is interposable because aliases point to the local
// definition.
// TODO: Try to handle non-zero GEPs of local aliasees.
if (!Target)
if (!Target || Target->isInterposable())
continue;
Target->removeDeadConstantUsers();

12
llvm/test/Transforms/GlobalOpt/alias-resolve.ll
View File

@ -16,11 +16,19 @@
@foo4 = weak_odr unnamed_addr alias i8*, getelementptr inbounds ([2 x i8*], [2 x i8*]* @bar4, i32 0, i32 1)
; CHECK: @foo4 = weak_odr unnamed_addr alias i8*, getelementptr inbounds ([2 x i8*], [2 x i8*]* @bar4, i32 0, i32 1)
@priva = private alias void (), void ()* @bar5
; CHECK: @priva = private alias void (), void ()* @bar5
define void @bar2() {
ret void
}
; CHECK: define void @bar2()
define weak void @bar5() {
ret void
}
; CHECK: define weak void @bar5()
define void @baz() {
entry:
call void @foo1()
@ -34,6 +42,10 @@ entry:
call void @weak1()
; CHECK: call void @weak1()
call void @priva()
; CHECK: call void @priva()
ret void
}