[GlobalMerge] Use private linkage for MergedGlobals variables

[john.brawn]

Summary

Other objects can never reference the MergedGlobals symbol so external linkage is never needed. Using private instead of internal linkage means the object is more similar to what it looks like when global merging is not enabled, with the only difference being that the merged variables are addressed indirectly relative to the start of the section they are in.

Also add aliases for merged variables with internal linkage, as this also makes the object be more like what it is when they are not merged.

[• rafael]

LGTM

[ab]

This means we'll start emitting aliases even when -global-merge-on-external=false (mach-o), right? As I explained on the other review, this is probably not OK on darwin.

[john.brawn]

In D11942#222309, @ab wrote:

This means we'll start emitting aliases even when -global-merge-on-external=false (mach-o), right? As I explained on the other review, this is probably not OK on darwin.

Yes, I think you're right. Fixed in r244748, and also added some tests to check for that.

lib/CodeGen/GlobalMerge.cpp

bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable *> &Globals,
 
   ssize_t i = GlobalSet.find_first();
   while (i != -1) {
     ssize_t j = 0;
     uint64_t MergedSize = 0;
     std::vector<Type*> Tys;
     std::vector<Constant*> Inits;
 
-    bool HasExternal = false;
-    GlobalVariable *TheFirstExternal = 0;
     for (j = i; j != -1; j = GlobalSet.find_next(j)) {
       Type *Ty = Globals[j]->getType()->getElementType();
       MergedSize += DL.getTypeAllocSize(Ty);
       if (MergedSize > MaxOffset) {
         break;
       }
       Tys.push_back(Ty);
       Inits.push_back(Globals[j]->getInitializer());
-
-      if (Globals[j]->hasExternalLinkage() && !HasExternal) {
-        HasExternal = true;
-        TheFirstExternal = Globals[j];
-      }
     }
 
-    // If merged variables doesn't have external linkage, we needn't to expose
-    // the symbol after merging.
-    GlobalValue::LinkageTypes Linkage = HasExternal
-                                            ? GlobalValue::ExternalLinkage
-                                            : GlobalValue::InternalLinkage;
-
     StructType *MergedTy = StructType::get(M.getContext(), Tys);
     Constant *MergedInit = ConstantStruct::get(MergedTy, Inits);
 
-    // If merged variables have external linkage, we use symbol name of the
-    // first variable merged as the suffix of global symbol name. This would
-    // be able to avoid the link-time naming conflict for globalm symbols.
     GlobalVariable *MergedGV = new GlobalVariable(
-        M, MergedTy, isConst, Linkage, MergedInit,
-        HasExternal ? "_MergedGlobals_" + TheFirstExternal->getName()
-                    : "_MergedGlobals",
-        nullptr, GlobalVariable::NotThreadLocal, AddrSpace);
+        M, MergedTy, isConst, GlobalValue::PrivateLinkage, MergedInit,
+        "_MergedGlobals", nullptr, GlobalVariable::NotThreadLocal, AddrSpace);
 
     for (ssize_t k = i, idx = 0; k != j; k = GlobalSet.find_next(k)) {
       GlobalValue::LinkageTypes Linkage = Globals[k]->getLinkage();
       std::string Name = Globals[k]->getName();
 
       Constant *Idx[2] = {
         ConstantInt::get(Int32Ty, 0),
         ConstantInt::get(Int32Ty, idx++)
       };
       Constant *GEP =
           ConstantExpr::getInBoundsGetElementPtr(MergedTy, MergedGV, Idx);
       Globals[k]->replaceAllUsesWith(GEP);
       Globals[k]->eraseFromParent();
 
-      if (Linkage != GlobalValue::InternalLinkage) {
-        // Generate a new alias...
-        auto *PTy = cast<PointerType>(GEP->getType());
-        GlobalAlias::create(PTy, Linkage, Name, GEP, &M);
-      }
 
       NumMerged++;
     }
     i = j;
   }
 
   return true;
 }

test/CodeGen/AArch64/global-merge-1.ll

 ; RUN: llc %s -mtriple=aarch64-none-linux-gnu -aarch64-global-merge -o - | FileCheck %s
 ; RUN: llc %s -mtriple=aarch64-none-linux-gnu -aarch64-global-merge -global-merge-on-external -o - | FileCheck %s
 
 ; RUN: llc %s -mtriple=aarch64-linux-gnuabi -aarch64-global-merge -o - | FileCheck %s
 ; RUN: llc %s -mtriple=aarch64-linux-gnuabi -aarch64-global-merge -global-merge-on-external -o - | FileCheck %s
 
 ; RUN: llc %s -mtriple=aarch64-apple-ios -aarch64-global-merge -o - | FileCheck %s --check-prefix=CHECK-APPLE-IOS
 ; RUN: llc %s -mtriple=aarch64-apple-ios -aarch64-global-merge -global-merge-on-external -o - | FileCheck %s --check-prefix=CHECK-APPLE-IOS
 
 @m = internal global i32 0, align 4
 @n = internal global i32 0, align 4
 
 define void @f1(i32 %a1, i32 %a2) {
 ;CHECK-APPLE-IOS-NOT: adrp
-;CHECK-APPLE-IOS: adrp  x8, __MergedGlobals@PAGE
+;CHECK-APPLE-IOS: adrp  x8, l__MergedGlobals@PAGE
 ;CHECK-APPLE-IOS-NOT: adrp
-;CHECK-APPLE-IOS: add x8, x8, __MergedGlobals@PAGEOFF
+;CHECK-APPLE-IOS: add x8, x8, l__MergedGlobals@PAGEOFF
   store i32 %a1, i32* @m, align 4
   store i32 %a2, i32* @n, align 4
   ret void
 }
 
-;CHECK: .type _MergedGlobals,@object  // @_MergedGlobals
-;CHECK: .local  _MergedGlobals
-;CHECK: .comm _MergedGlobals,8,8
+;CHECK: .type .L_MergedGlobals,@object  // @_MergedGlobals
+;CHECK: .local  .L_MergedGlobals
+;CHECK: .comm .L_MergedGlobals,8,8
 
-;CHECK-APPLE-IOS: .zerofill __DATA,__bss,__MergedGlobals,8,3 ; @_MergedGlobals
+;CHECK-APPLE-IOS: .zerofill __DATA,__bss,l__MergedGlobals,8,3 ; @_MergedGlobals

test/CodeGen/AArch64/global-merge-2.ll

 ; RUN: llc %s -mtriple=aarch64-none-linux-gnu -aarch64-global-merge -global-merge-on-external -o - | FileCheck %s
 ; RUN: llc %s -mtriple=aarch64-linux-gnuabi -aarch64-global-merge -global-merge-on-external -o - | FileCheck %s
 ; RUN: llc %s -mtriple=aarch64-apple-ios -aarch64-global-merge -global-merge-on-external -o - | FileCheck %s --check-prefix=CHECK-APPLE-IOS
 
 @x = global i32 0, align 4
 @y = global i32 0, align 4
 @z = global i32 0, align 4
 
 define void @f1(i32 %a1, i32 %a2) {
 ;CHECK-APPLE-IOS-LABEL: _f1:
 ;CHECK-APPLE-IOS-NOT: adrp
-;CHECK-APPLE-IOS: adrp  x8, __MergedGlobals_x@PAGE
-;CHECK-APPLE-IOS: add x8, x8, __MergedGlobals_x@PAGEOFF
+;CHECK-APPLE-IOS: adrp  x8, l__MergedGlobals@PAGE
+;CHECK-APPLE-IOS: add x8, x8, l__MergedGlobals@PAGEOFF
 ;CHECK-APPLE-IOS-NOT: adrp
   store i32 %a1, i32* @x, align 4
   store i32 %a2, i32* @y, align 4
   ret void
 }
 
 define void @g1(i32 %a1, i32 %a2) {
 ;CHECK-APPLE-IOS-LABEL: _g1:
-;CHECK-APPLE-IOS: adrp  x8, __MergedGlobals_x@PAGE
-;CHECK-APPLE-IOS: add x8, x8, __MergedGlobals_x@PAGEOFF
+;CHECK-APPLE-IOS: adrp  x8, l__MergedGlobals@PAGE
+;CHECK-APPLE-IOS: add x8, x8, l__MergedGlobals@PAGEOFF
 ;CHECK-APPLE-IOS-NOT: adrp
   store i32 %a1, i32* @y, align 4
   store i32 %a2, i32* @z, align 4
   ret void
 }
 
-;CHECK: .type _MergedGlobals_x,@object // @_MergedGlobals_x
-;CHECK: .globl  _MergedGlobals_x
-;CHECK: .align  3
-;CHECK: _MergedGlobals_x:
-;CHECK: .size _MergedGlobals_x, 12
+;CHECK: .type .L_MergedGlobals,@object // @_MergedGlobals
+;CHECK: .local  .L_MergedGlobals
+;CHECK: .comm .L_MergedGlobals,12,8
 
 ;CHECK: .globl  x
-;CHECK: x = _MergedGlobals_x
+;CHECK: x = .L_MergedGlobals
 ;CHECK: .globl  y
-;CHECK: y = _MergedGlobals_x+4
+;CHECK: y = .L_MergedGlobals+4
 ;CHECK: .globl  z
-;CHECK: z = _MergedGlobals_x+8
+;CHECK: z = .L_MergedGlobals+8
 
-;CHECK-APPLE-IOS: .globl  __MergedGlobals_x       ; @_MergedGlobals_x
-;CHECK-APPLE-IOS: .zerofill __DATA,__common,__MergedGlobals_x,12,3
+;CHECK-APPLE-IOS: .zerofill __DATA,__bss,l__MergedGlobals,12,3
 
 ;CHECK-APPLE-IOS: .globl  _x
-;CHECK-APPLE-IOS: _x = __MergedGlobals_x
+;CHECK-APPLE-IOS:  = l__MergedGlobals
 ;CHECK-APPLE-IOS: .globl  _y
-;CHECK-APPLE-IOS: _y = __MergedGlobals_x+4
+;CHECK-APPLE-IOS: _y = l__MergedGlobals+4
 ;CHECK-APPLE-IOS: .globl  _z
-;CHECK-APPLE-IOS: _z = __MergedGlobals_x+8
+;CHECK-APPLE-IOS: _z = l__MergedGlobals+8
 ;CHECK-APPLE-IOS: .subsections_via_symbols

test/CodeGen/AArch64/global-merge-3.ll

 ; RUN: llc %s -mtriple=aarch64-none-linux-gnu -aarch64-global-merge -global-merge-on-external -o - | FileCheck %s
 ; RUN: llc %s -mtriple=aarch64-linux-gnuabi -aarch64-global-merge -global-merge-on-external -o - | FileCheck %s
 ; RUN: llc %s -mtriple=aarch64-apple-ios -aarch64-global-merge -global-merge-on-external -o - | FileCheck %s --check-prefix=CHECK-APPLE-IOS
 
 @x = global [1000 x i32] zeroinitializer, align 1
 @y = global [1000 x i32] zeroinitializer, align 1
 @z = internal global i32 1, align 4
 
 define void @f1(i32 %a1, i32 %a2, i32 %a3) {
-;CHECK-APPLE-IOS: adrp  x8, __MergedGlobals_x@PAGE
+;CHECK-APPLE-IOS: adrp  x8, l__MergedGlobals@PAGE
 ;CHECK-APPLE-IOS-NOT: adrp
-;CHECK-APPLE-IOS: add x8, x8, __MergedGlobals_x@PAGEOFF
-;CHECK-APPLE-IOS: adrp  x9, __MergedGlobals_y@PAGE
-;CHECK-APPLE-IOS: add x9, x9, __MergedGlobals_y@PAGEOFF
+;CHECK-APPLE-IOS: add x8, x8, l__MergedGlobals@PAGEOFF
+;CHECK-APPLE-IOS: adrp  x9, l__MergedGlobals.1@PAGE
+;CHECK-APPLE-IOS: add x9, x9, l__MergedGlobals.1@PAGEOFF
   %x3 = getelementptr inbounds [1000 x i32], [1000 x i32]* @x, i32 0, i64 3
   %y3 = getelementptr inbounds [1000 x i32], [1000 x i32]* @y, i32 0, i64 3
   store i32 %a1, i32* %x3, align 4
   store i32 %a2, i32* %y3, align 4
   store i32 %a3, i32* @z, align 4
   ret void
 }
 
-;CHECK: .type _MergedGlobals_x,@object // @_MergedGlobals_x
-;CHECK: .globl  _MergedGlobals_x
+;CHECK: .type .L_MergedGlobals,@object // @_MergedGlobals
 ;CHECK: .align  4
-;CHECK: _MergedGlobals_x:
-;CHECK: .size _MergedGlobals_x, 4004
+;CHECK: .L_MergedGlobals:
+;CHECK: .size .L_MergedGlobals, 4004
 
-;CHECK: .type _MergedGlobals_y,@object // @_MergedGlobals_y
-;CHECK: .globl  _MergedGlobals_y
-;CHECK: _MergedGlobals_y:
-;CHECK: .size _MergedGlobals_y, 4000
+;CHECK: .type .L_MergedGlobals.1,@object // @_MergedGlobals.1
+;CHECK: .local  .L_MergedGlobals.1
+;CHECK: .comm .L_MergedGlobals.1,4000,16
 
-;CHECK-APPLE-IOS: .globl  __MergedGlobals_x       ; @_MergedGlobals_x
 ;CHECK-APPLE-IOS: .align  4
-;CHECK-APPLE-IOS:  __MergedGlobals_x:
+;CHECK-APPLE-IOS:  l__MergedGlobals:
 ;CHECK-APPLE-IOS: .long 1
 ;CHECK-APPLE-IOS: .space  4000
 
-;CHECK-APPLE-IOS: .globl  __MergedGlobals_y       ; @_MergedGlobals_y
-;CHECK-APPLE-IOS: .zerofill __DATA,__common,__MergedGlobals_y,4000,4
+;CHECK-APPLE-IOS: .zerofill __DATA,__bss,l__MergedGlobals.1,4000,4
 
 ;CHECK: .globl  x
-;CHECK: x = _MergedGlobals_x+4
+;CHECK: x = .L_MergedGlobals+4
 ;CHECK: .globl  y
-;CHECK: y = _MergedGlobals_y
+;CHECK: y = .L_MergedGlobals.1
 
 ;CHECK-APPLE-IOS:.globl _x
-;CHECK-APPLE-IOS: _x = __MergedGlobals_x+4
+;CHECK-APPLE-IOS: _x = l__MergedGlobals+4
 ;CHECK-APPLE-IOS:.globl _y
-;CHECK-APPLE-IOS: _y = __MergedGlobals_y
+;CHECK-APPLE-IOS: _y = l__MergedGlobals.1

test/CodeGen/AArch64/global-merge-4.ll

define internal void @calculate() #0 {
   ret void
 }
 
 ; Function Attrs: nounwind readnone ssp
 define internal i32* @returnFoo() #1 {
   ret i32* getelementptr inbounds ([5 x i32], [5 x i32]* @foo, i64 0, i64 0)
 }
 
-;CHECK: .type _MergedGlobals,@object  // @_MergedGlobals
-;CHECK: .local  _MergedGlobals
-;CHECK: .comm _MergedGlobals,60,16
+;CHECK: .type .L_MergedGlobals,@object  // @_MergedGlobals
+;CHECK: .local  .L_MergedGlobals
+;CHECK: .comm .L_MergedGlobals,60,16
 
 attributes #0 = { nounwind ssp }
 attributes #1 = { nounwind readnone ssp }
 attributes #2 = { nounwind }

test/CodeGen/AArch64/global-merge-group-by-use.ll

 ; RUN: llc -mtriple=aarch64-apple-ios -asm-verbose=false -aarch64-collect-loh=false \
 ; RUN:   -aarch64-global-merge -global-merge-group-by-use -global-merge-ignore-single-use=false \
 ; RUN:   %s -o - | FileCheck %s
 
 ; We assume that globals of the same size aren't reordered inside a set.
 
 ; Check that we create two MergedGlobal instances for two functions using
 ; disjoint sets of globals
 
 @m1 = internal global i32 0, align 4
 @n1 = internal global i32 0, align 4
 
 ; CHECK-LABEL: f1:
 define void @f1(i32 %a1, i32 %a2) #0 {
-; CHECK-NEXT: adrp x8, [[SET1:__MergedGlobals.[0-9]*]]@PAGE
+; CHECK-NEXT: adrp x8, [[SET1:l__MergedGlobals.[0-9]*]]@PAGE
 ; CHECK-NEXT: add x8, x8, [[SET1]]@PAGEOFF
 ; CHECK-NEXT: stp w0, w1, [x8]
 ; CHECK-NEXT: ret
   store i32 %a1, i32* @m1, align 4
   store i32 %a2, i32* @n1, align 4
   ret void
 }
 
 @m2 = internal global i32 0, align 4
 @n2 = internal global i32 0, align 4
 @o2 = internal global i32 0, align 4
 
 ; CHECK-LABEL: f2:
 define void @f2(i32 %a1, i32 %a2, i32 %a3) #0 {
-; CHECK-NEXT: adrp x8, [[SET2:__MergedGlobals.[0-9]*]]@PAGE
+; CHECK-NEXT: adrp x8, [[SET2:l__MergedGlobals.[0-9]*]]@PAGE
 ; CHECK-NEXT: add x8, x8, [[SET2]]@PAGEOFF
 ; CHECK-NEXT: stp w0, w1, [x8]
 ; CHECK-NEXT: str w2, [x8, #8]
 ; CHECK-NEXT: ret
   store i32 %a1, i32* @m2, align 4
   store i32 %a2, i32* @n2, align 4
   store i32 %a3, i32* @o2, align 4
   ret void
 }
 
 ; Sanity-check (don't worry about cost models) that we pick the biggest subset
 ; of all global used "together" directly or indirectly.  Here, that means
 ; merging n3, m4, and n4 together, but ignoring m3.
 
 @m3 = internal global i32 0, align 4
 @n3 = internal global i32 0, align 4
 
 ; CHECK-LABEL: f3:
 define void @f3(i32 %a1, i32 %a2) #0 {
 ; CHECK-NEXT: adrp x8, _m3@PAGE
-; CHECK-NEXT: adrp x9, [[SET3:__MergedGlobals[0-9]*]]@PAGE
+; CHECK-NEXT: adrp x9, [[SET3:l__MergedGlobals[0-9]*]]@PAGE
 ; CHECK-NEXT: str w0, [x8, _m3@PAGEOFF]
 ; CHECK-NEXT: str w1, [x9, [[SET3]]@PAGEOFF]
 ; CHECK-NEXT: ret
   store i32 %a1, i32* @m3, align 4
   store i32 %a2, i32* @n3, align 4
   ret void
 }
 

test/CodeGen/AArch64/global-merge-ignore-single-use-minsize.ll

 ; RUN: llc -mtriple=aarch64-apple-ios -asm-verbose=false -aarch64-collect-loh=false \
 ; RUN:   -O1 -global-merge-group-by-use -global-merge-ignore-single-use \
 ; RUN:   %s -o - | FileCheck %s
 
 ; Check that, at -O1, we only merge globals used in minsize functions.
 ; We assume that globals of the same size aren't reordered inside a set.
 ; We use -global-merge-ignore-single-use, and thus only expect one merged set.
 
 @m1 = internal global i32 0, align 4
 @n1 = internal global i32 0, align 4
 
 ; CHECK-LABEL: f1:
 define void @f1(i32 %a1, i32 %a2) minsize nounwind {
-; CHECK-NEXT: adrp x8, [[SET:__MergedGlobals]]@PAGE
+; CHECK-NEXT: adrp x8, [[SET:l__MergedGlobals]]@PAGE
 ; CHECK-NEXT: add x8, x8, [[SET]]@PAGEOFF
 ; CHECK-NEXT: stp w0, w1, [x8]
 ; CHECK-NEXT: ret
   store i32 %a1, i32* @m1, align 4
   store i32 %a2, i32* @n1, align 4
   ret void
 }
 

test/CodeGen/AArch64/global-merge-ignore-single-use.ll

 ; RUN: llc -mtriple=aarch64-apple-ios -asm-verbose=false -aarch64-collect-loh=false \
 ; RUN:   -aarch64-global-merge -global-merge-group-by-use -global-merge-ignore-single-use \
 ; RUN:   %s -o - | FileCheck %s
 
 ; We assume that globals of the same size aren't reordered inside a set.
 
 @m1 = internal global i32 0, align 4
 @n1 = internal global i32 0, align 4
 @o1 = internal global i32 0, align 4
 
 ; CHECK-LABEL: f1:
 define void @f1(i32 %a1, i32 %a2) #0 {
-; CHECK-NEXT: adrp x8, [[SET:__MergedGlobals]]@PAGE
+; CHECK-NEXT: adrp x8, [[SET:l__MergedGlobals]]@PAGE
 ; CHECK-NEXT: add x8, x8, [[SET]]@PAGEOFF
 ; CHECK-NEXT: stp w0, w1, [x8]
 ; CHECK-NEXT: ret
   store i32 %a1, i32* @m1, align 4
   store i32 %a2, i32* @n1, align 4
   ret void
 }
 

test/CodeGen/ARM/2011-06-29-MergeGlobalsAlign.ll

 ; RUN: llc < %s -mtriple=thumbv7-apple-darwin10 -arm-global-merge -global-merge-group-by-use=false | FileCheck %s
-; CHECK: .zerofill __DATA,__bss,__MergedGlobals,16,2
+; CHECK: .zerofill __DATA,__bss,l__MergedGlobals,16,2
 
 @prev = external global [0 x i16]
 @max_lazy_match = internal unnamed_addr global i32 0, align 4
 @read_buf = external global i32 (i8*, i32)*
 @window = external global [0 x i8]
 @lookahead = internal unnamed_addr global i32 0, align 4
 @eofile.b = internal unnamed_addr global i32 0
 @ins_h = internal unnamed_addr global i32 0, align 4

test/CodeGen/ARM/global-merge-1.ll

 ; RUN: llc %s -O0 -o - | FileCheck -check-prefix=NO-MERGE %s
 ; RUN: llc %s -O0 -o - -arm-global-merge=false | FileCheck -check-prefix=NO-MERGE %s
 ; RUN: llc %s -O0 -o - -arm-global-merge=true | FileCheck -check-prefix=MERGE %s
 ; RUN: llc %s -O1 -o - | FileCheck -check-prefix=NO-MERGE %s
 ; RUN: llc %s -O1 -o - -arm-global-merge=false | FileCheck -check-prefix=NO-MERGE %s
 ; RUN: llc %s -O1 -o - -arm-global-merge=true | FileCheck -check-prefix=MERGE %s
 ; RUN: llc %s -O3 -o - | FileCheck -check-prefix=MERGE %s
 ; RUN: llc %s -O3 -o - -arm-global-merge=false | FileCheck -check-prefix=NO-MERGE %s
 ; RUN: llc %s -O3 -o - -arm-global-merge=true | FileCheck -check-prefix=MERGE %s
 
 ; MERGE-NOT: .zerofill __DATA,__bss,_bar,20,2
 ; MERGE-NOT: .zerofill __DATA,__bss,_baz,20,2
 ; MERGE-NOT: .zerofill __DATA,__bss,_foo,20,2
-; MERGE: .zerofill __DATA,__bss,__MergedGlobals,60,4
+; MERGE: .zerofill __DATA,__bss,l__MergedGlobals,60,4
 ; MERGE-NOT: .zerofill __DATA,__bss,_bar,20,2
 ; MERGE-NOT: .zerofill __DATA,__bss,_baz,20,2
 ; MERGE-NOT: .zerofill __DATA,__bss,_foo,20,2
 
-; NO-MERGE-NOT: .zerofill __DATA,__bss,__MergedGlobals,60,4
+; NO-MERGE-NOT: .zerofill __DATA,__bss,l__MergedGlobals,60,4
 ; NO-MERGE: .zerofill __DATA,__bss,_bar,20,2
 ; NO-MERGE: .zerofill __DATA,__bss,_baz,20,2
 ; NO-MERGE: .zerofill __DATA,__bss,_foo,20,2
-; NO-MERGE-NOT: .zerofill __DATA,__bss,__MergedGlobals,60,4
+; NO-MERGE-NOT: .zerofill __DATA,__bss,l__MergedGlobals,60,4
 
 target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:32:64-v128:32:128-a0:0:32-n32-S32"
 target triple = "thumbv7-apple-ios3.0.0"
 
 @bar = internal global [5 x i32] zeroinitializer, align 4
 @baz = internal global [5 x i32] zeroinitializer, align 4
 @foo = internal global [5 x i32] zeroinitializer, align 4
 

test/CodeGen/ARM/global-merge-external.ll

 ; RUN: llc < %s -mtriple=arm-eabi  -arm-global-merge                                 | FileCheck %s --check-prefix=CHECK-MERGE
 ; RUN: llc < %s -mtriple=arm-eabi  -arm-global-merge -global-merge-on-external=true  | FileCheck %s --check-prefix=CHECK-MERGE
 ; RUN: llc < %s -mtriple=arm-eabi  -arm-global-merge -global-merge-on-external=false | FileCheck %s --check-prefix=CHECK-NO-MERGE
 ; RUN: llc < %s -mtriple=arm-macho -arm-global-merge                                 | FileCheck %s --check-prefix=CHECK-NO-MERGE
 
 @x = global i32 0, align 4
 @y = global i32 0, align 4
 @z = global i32 0, align 4
 
 define void @f1(i32 %a1, i32 %a2) {
 ;CHECK:          f1:
 ;CHECK:          ldr {{r[0-9]+}}, [[LABEL1:\.LCPI[0-9]+_[0-9]]]
 ;CHECK:          [[LABEL1]]:
-;CHECK-MERGE:    .long _MergedGlobals_x
+;CHECK-MERGE:    .long .L_MergedGlobals
 ;CHECK-NO-MERGE: .long {{_?x}}
   store i32 %a1, i32* @x, align 4
   store i32 %a2, i32* @y, align 4
   ret void
 }
 
 define void @g1(i32 %a1, i32 %a2) {
 ;CHECK:          g1:
 ;CHECK:          ldr {{r[0-9]+}}, [[LABEL2:\.LCPI[0-9]+_[0-9]]]
 ;CHECK:          [[LABEL2]]:
-;CHECK-MERGE:    .long _MergedGlobals_x
+;CHECK-MERGE:    .long .L_MergedGlobals
 ;CHECK-NO-MERGE: .long {{_?y}}
   store i32 %a1, i32* @y, align 4
   store i32 %a2, i32* @z, align 4
   ret void
 }
 
-;CHECK-NO-MERGE-NOT: .globl _MergedGlobals_x
+;CHECK-NO-MERGE-NOT: .globl .L_MergedGlobals
 
-;CHECK-MERGE: .type _MergedGlobals_x,%object
-;CHECK-MERGE: .globl  _MergedGlobals_x
-;CHECK-MERGE: .align  2
-;CHECK-MERGE: _MergedGlobals_x:
-;CHECK-MERGE: .size _MergedGlobals_x, 12
+;CHECK-MERGE: .type .L_MergedGlobals,%object
+;CHECK-MERGE: .local  .L_MergedGlobals
+;CHECK-MERGE: .comm .L_MergedGlobals,12,4
 
 ;CHECK-MERGE: .globl  x
-;CHECK-MERGE: x = _MergedGlobals_x
+;CHECK-MERGE: x = .L_MergedGlobals
 ;CHECK-MERGE: .globl  y
-;CHECK-MERGE: y = _MergedGlobals_x+4
+;CHECK-MERGE: y = .L_MergedGlobals+4
 ;CHECK-MERGE: .globl  z
-;CHECK-MERGE: z = _MergedGlobals_x+8
+;CHECK-MERGE: z = .L_MergedGlobals+8