[GlobalMerge] Only emit aliases for internal linkage variables for non-Mach-O
On Mach-O emitting aliases for the variables that make up a MergedGlobals
variable can cause problems when linking with dead stripping enabled so don't
do that, except for external variables where we must emit an alias.
llvm-svn: 244748
diff --git a/llvm/lib/CodeGen/GlobalMerge.cpp b/llvm/lib/CodeGen/GlobalMerge.cpp
index 3a7e2f4..d8739c4 100644
--- a/llvm/lib/CodeGen/GlobalMerge.cpp
+++ b/llvm/lib/CodeGen/GlobalMerge.cpp
@@ -459,9 +459,16 @@
Globals[k]->replaceAllUsesWith(GEP);
Globals[k]->eraseFromParent();
- // Generate a new alias...
- auto *PTy = cast<PointerType>(GEP->getType());
- GlobalAlias::create(PTy, Linkage, Name, GEP, &M);
+ // When the linkage is not internal we must emit an alias for the original
+ // variable name as it may be accessed from another object. On non-Mach-O
+ // we can also emit an alias for internal linkage as it's safe to do so.
+ // It's not safe on Mach-O as the alias (and thus the portion of the
+ // MergedGlobals variable) may be dead stripped at link time.
+ if (Linkage != GlobalValue::InternalLinkage ||
+ !TM->getTargetTriple().isOSBinFormatMachO()) {
+ auto *PTy = cast<PointerType>(GEP->getType());
+ GlobalAlias::create(PTy, Linkage, Name, GEP, &M);
+ }
NumMerged++;
}
diff --git a/llvm/test/CodeGen/AArch64/global-merge-1.ll b/llvm/test/CodeGen/AArch64/global-merge-1.ll
index 304d0a7..b93f41c 100644
--- a/llvm/test/CodeGen/AArch64/global-merge-1.ll
+++ b/llvm/test/CodeGen/AArch64/global-merge-1.ll
@@ -23,5 +23,9 @@
;CHECK: .type .L_MergedGlobals,@object // @_MergedGlobals
;CHECK: .local .L_MergedGlobals
;CHECK: .comm .L_MergedGlobals,8,8
+;CHECK: m = .L_MergedGlobals
+;CHECK: n = .L_MergedGlobals+4
;CHECK-APPLE-IOS: .zerofill __DATA,__bss,l__MergedGlobals,8,3 ; @_MergedGlobals
+;CHECK-APPLE-IOS-NOT: _m = l__MergedGlobals
+;CHECK-APPLE-IOS-NOT: _n = l__MergedGlobals+4
diff --git a/llvm/test/CodeGen/AArch64/global-merge-3.ll b/llvm/test/CodeGen/AArch64/global-merge-3.ll
index a6a8a7e..095fa4f 100644
--- a/llvm/test/CodeGen/AArch64/global-merge-3.ll
+++ b/llvm/test/CodeGen/AArch64/global-merge-3.ll
@@ -36,11 +36,13 @@
;CHECK-APPLE-IOS: .zerofill __DATA,__bss,l__MergedGlobals.1,4000,4
+;CHECK: z = .L_MergedGlobals
;CHECK: .globl x
;CHECK: x = .L_MergedGlobals+4
;CHECK: .globl y
;CHECK: y = .L_MergedGlobals.1
+;CHECK-APPLE-IOS-NOT: _z = l__MergedGlobals
;CHECK-APPLE-IOS:.globl _x
;CHECK-APPLE-IOS: _x = l__MergedGlobals+4
;CHECK-APPLE-IOS:.globl _y