[GlobalMerge] Use private linkage for MergedGlobals variables

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.

Differential Revision: http://reviews.llvm.org/D11942

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244615 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/GlobalMerge.cpp b/lib/CodeGen/GlobalMerge.cpp
index d477143..3a7e2f4 100644 (file)
--- a/lib/CodeGen/GlobalMerge.cpp
+++ b/lib/CodeGen/GlobalMerge.cpp
@@ -429,8 +429,6 @@ bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable *> &Globals,
     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);
@@ -439,30 +437,14 @@ bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable *> &Globals,
       }
       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();
@@ -477,11 +459,9 @@ bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable *> &Globals,
       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);
-      }
+      // Generate a new alias...
+      auto *PTy = cast<PointerType>(GEP->getType());
+      GlobalAlias::create(PTy, Linkage, Name, GEP, &M);
 
       NumMerged++;
     }

diff --git a/test/CodeGen/AArch64/global-merge-1.ll b/test/CodeGen/AArch64/global-merge-1.ll
index 14b0430..304d0a7 100644 (file)
--- a/test/CodeGen/AArch64/global-merge-1.ll
+++ b/test/CodeGen/AArch64/global-merge-1.ll
@@ -12,16 +12,16 @@
 
 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

diff --git a/test/CodeGen/AArch64/global-merge-2.ll b/test/CodeGen/AArch64/global-merge-2.ll
index af68403..f168bea 100644 (file)
--- a/test/CodeGen/AArch64/global-merge-2.ll
+++ b/test/CodeGen/AArch64/global-merge-2.ll
@@ -9,8 +9,8 @@
 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
@@ -19,34 +19,31 @@ define void @f1(i32 %a1, i32 %a2) {
 
 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

diff --git a/test/CodeGen/AArch64/global-merge-3.ll b/test/CodeGen/AArch64/global-merge-3.ll
index 9251083..a6a8a7e 100644 (file)
--- a/test/CodeGen/AArch64/global-merge-3.ll
+++ b/test/CodeGen/AArch64/global-merge-3.ll
@@ -7,11 +7,11 @@
 @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
@@ -20,32 +20,28 @@ define void @f1(i32 %a1, i32 %a2, i32 %a3) {
   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

diff --git a/test/CodeGen/AArch64/global-merge-4.ll b/test/CodeGen/AArch64/global-merge-4.ll
index bc6b68a..a5109f6 100644 (file)
--- a/test/CodeGen/AArch64/global-merge-4.ll
+++ b/test/CodeGen/AArch64/global-merge-4.ll
@@ -64,9 +64,9 @@ 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 }

diff --git a/test/CodeGen/AArch64/global-merge-group-by-use.ll b/test/CodeGen/AArch64/global-merge-group-by-use.ll
index ddc044e..8b3fc97 100644 (file)
--- a/test/CodeGen/AArch64/global-merge-group-by-use.ll
+++ b/test/CodeGen/AArch64/global-merge-group-by-use.ll
@@ -12,7 +12,7 @@
 
 ; 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
@@ -27,7 +27,7 @@ define void @f1(i32 %a1, i32 %a2) #0 {
 
 ; 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]
@@ -48,7 +48,7 @@ define void @f2(i32 %a1, i32 %a2, i32 %a3) #0 {
 ; 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

diff --git a/test/CodeGen/AArch64/global-merge-ignore-single-use-minsize.ll b/test/CodeGen/AArch64/global-merge-ignore-single-use-minsize.ll
index e83cbab..3994389 100644 (file)
--- a/test/CodeGen/AArch64/global-merge-ignore-single-use-minsize.ll
+++ b/test/CodeGen/AArch64/global-merge-ignore-single-use-minsize.ll
@@ -11,7 +11,7 @@
 
 ; 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

diff --git a/test/CodeGen/AArch64/global-merge-ignore-single-use.ll b/test/CodeGen/AArch64/global-merge-ignore-single-use.ll
index e6de469..c3756a8 100644 (file)
--- a/test/CodeGen/AArch64/global-merge-ignore-single-use.ll
+++ b/test/CodeGen/AArch64/global-merge-ignore-single-use.ll
@@ -10,7 +10,7 @@
 
 ; 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

diff --git a/test/CodeGen/ARM/2011-06-29-MergeGlobalsAlign.ll b/test/CodeGen/ARM/2011-06-29-MergeGlobalsAlign.ll
index aac8f7b..1097050 100644 (file)
--- a/test/CodeGen/ARM/2011-06-29-MergeGlobalsAlign.ll
+++ b/test/CodeGen/ARM/2011-06-29-MergeGlobalsAlign.ll
@@ -1,5 +1,5 @@
 ; 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

diff --git a/test/CodeGen/ARM/global-merge-1.ll b/test/CodeGen/ARM/global-merge-1.ll
index d4d9b0f..a3cbe8a 100644 (file)
--- a/test/CodeGen/ARM/global-merge-1.ll
+++ b/test/CodeGen/ARM/global-merge-1.ll
@@ -11,16 +11,16 @@
 ; 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"

diff --git a/test/CodeGen/ARM/global-merge-external.ll b/test/CodeGen/ARM/global-merge-external.ll
index 0dd3f47..f379e65 100644 (file)
--- a/test/CodeGen/ARM/global-merge-external.ll
+++ b/test/CodeGen/ARM/global-merge-external.ll
@@ -11,7 +11,7 @@ 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
@@ -22,24 +22,22 @@ 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