[MergeFunc] Erase unused duplicate functions if they are discardable
MergeFunc only deletes unused duplicate functions if they have local
linkage, but it should be safe to relax this to any "discardable if
unused" linkage type.
Differential Revision: https://reviews.llvm.org/D56574
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350939 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/MergeFunctions.cpp b/lib/Transforms/IPO/MergeFunctions.cpp
index 30fe9bbb..11efe95 100644
--- a/lib/Transforms/IPO/MergeFunctions.cpp
+++ b/lib/Transforms/IPO/MergeFunctions.cpp
@@ -845,7 +845,7 @@
// If G was internal then we may have replaced all uses of G with F. If so,
// stop here and delete G. There's no need for a thunk. (See note on
// MergeFunctionsPDI above).
- if (G->hasLocalLinkage() && G->use_empty() && !MergeFunctionsPDI) {
+ if (G->isDiscardableIfUnused() && G->use_empty() && !MergeFunctionsPDI) {
G->eraseFromParent();
++NumFunctionsMerged;
return;
diff --git a/test/Transforms/MergeFunc/linkonce_odr.ll b/test/Transforms/MergeFunc/linkonce_odr.ll
index 1ad0d72..825f905 100644
--- a/test/Transforms/MergeFunc/linkonce_odr.ll
+++ b/test/Transforms/MergeFunc/linkonce_odr.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -mergefunc < %s | FileCheck %s
+; RUN: opt -S -mergefunc < %s | FileCheck %s -implicit-check-not=funC
; Replacments should be totally ordered on the function name.
; If we don't do this we can end up with one module defining a thunk for @funA
@@ -15,6 +15,13 @@
; CHECK-NEXT: tail call i32 @funA(i32 %0, i32 %1)
; CHECK-NEXT: ret
+define linkonce_odr i32 @funC(i32 %x, i32 %y) {
+ %sum = add i32 %x, %y
+ %sum2 = add i32 %x, %sum
+ %sum3 = add i32 %x, %sum2
+ ret i32 %sum3
+}
+
define linkonce_odr i32 @funB(i32 %x, i32 %y) {
%sum = add i32 %x, %y
%sum2 = add i32 %x, %sum
@@ -28,3 +35,8 @@
%sum3 = add i32 %x, %sum2
ret i32 %sum3
}
+
+; This creates a use of @funB, preventing -mergefunc from deleting it.
+; @funC, however, can safely be deleted as it has no uses, and is discardable
+; if unused.
+@take_addr_of_funB = global i8* bitcast (i32 (i32, i32)* @funB to i8*)
