Revert "Use private linkage for MergedGlobals variables" on Darwin.

This is a partial revert of r244615 (http://reviews.llvm.org/D11942),
which caused a major regression in debug info quality.

Turning the artificial __MergedGlobal symbols into private symbols
(l__MergedGlobal) means that the linker will not include them in the
symbol table of the final executable. Without a symbol table entry
dsymutil is not be able to process the debug info for any of the
merged globals and thus drops the debug info for all of them.

This patch is enabling the old behavior for all MachO targets while
leaving all other targets unaffected.

rdar://problem/29160481
https://reviews.llvm.org/D26531

llvm-svn: 286607

diff --git a/llvm/lib/CodeGen/GlobalMerge.cpp b/llvm/lib/CodeGen/GlobalMerge.cpp
index 2d9e093..e0ffd47 100644 (file)
--- a/llvm/lib/CodeGen/GlobalMerge.cpp
+++ b/llvm/lib/CodeGen/GlobalMerge.cpp
@@ -432,6 +432,8 @@ bool GlobalMerge::doMerge(const SmallVectorImpl<GlobalVariable *> &Globals,
     std::vector<Type*> Tys;
     std::vector<Constant*> Inits;
 
+    bool HasExternal = false;
+    GlobalVariable *TheFirstExternal = nullptr;
     for (j = i; j != -1; j = GlobalSet.find_next(j)) {
       Type *Ty = Globals[j]->getValueType();
       MergedSize += DL.getTypeAllocSize(Ty);
@@ -440,14 +442,34 @@ bool GlobalMerge::doMerge(const 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);
 
-    GlobalVariable *MergedGV = new GlobalVariable(
-        M, MergedTy, isConst, GlobalValue::PrivateLinkage, MergedInit,
-        "_MergedGlobals", nullptr, GlobalVariable::NotThreadLocal, AddrSpace);
+    // On Darwin external linkage needs to be preserved, otherwise dsymutil
+    // cannot preserve the debug info for the merged variables.  If they have
+    // external linkage, use the symbol name of the first variable merged as the
+    // suffix of global symbol name.  This avoids a link-time naming conflict
+    // for the _MergedGlobals symbols.
+    Twine MergedName =
+        (IsMachO && HasExternal)
+            ? "_MergedGlobals_" + TheFirstExternal->getName()
+            : "_MergedGlobals";
+    auto MergedLinkage = IsMachO ? Linkage : GlobalValue::PrivateLinkage;
+    auto *MergedGV = new GlobalVariable(
+        M, MergedTy, isConst, MergedLinkage, MergedInit, MergedName, nullptr,
+        GlobalVariable::NotThreadLocal, AddrSpace);
 
     const StructLayout *MergedLayout = DL.getStructLayout(MergedTy);
 

diff --git a/llvm/test/CodeGen/AArch64/global-merge-1.ll b/llvm/test/CodeGen/AArch64/global-merge-1.ll
index 6c9b3cb..b5a28a1 100644 (file)
--- a/llvm/test/CodeGen/AArch64/global-merge-1.ll
+++ b/llvm/test/CodeGen/AArch64/global-merge-1.ll
@@ -12,9 +12,9 @@
 
 define void @f1(i32 %a1, i32 %a2) {
 ;CHECK-APPLE-IOS-NOT: adrp
-;CHECK-APPLE-IOS: adrp x8, l__MergedGlobals@PAGE
+;CHECK-APPLE-IOS: adrp x8, __MergedGlobals@PAGE
 ;CHECK-APPLE-IOS-NOT: adrp
-;CHECK-APPLE-IOS: add  x8, x8, l__MergedGlobals@PAGEOFF
+;CHECK-APPLE-IOS: add  x8, x8, __MergedGlobals@PAGEOFF
   store i32 %a1, i32* @m, align 4
   store i32 %a2, i32* @n, align 4
   ret void
@@ -26,6 +26,6 @@ define void @f1(i32 %a1, i32 %a2) {
 ;CHECK: m = .L_MergedGlobals
 ;CHECK: n = .L_MergedGlobals+4
 
-;CHECK-APPLE-IOS: .zerofill __DATA,__bss,l__MergedGlobals,8,3 ; @_MergedGlobals
+;CHECK-APPLE-IOS: .zerofill __DATA,__bss,__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-2.ll b/llvm/test/CodeGen/AArch64/global-merge-2.ll
index 10f3a94..6cd3f55 100644 (file)
--- a/llvm/test/CodeGen/AArch64/global-merge-2.ll
+++ b/llvm/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, l__MergedGlobals@PAGE
-;CHECK-APPLE-IOS: add  x8, x8, l__MergedGlobals@PAGEOFF
+;CHECK-APPLE-IOS: adrp x8, __MergedGlobals_x@PAGE
+;CHECK-APPLE-IOS: add  x8, x8, __MergedGlobals_x@PAGEOFF
 ;CHECK-APPLE-IOS-NOT: adrp
   store i32 %a1, i32* @x, align 4
   store i32 %a2, i32* @y, align 4
@@ -19,8 +19,8 @@ define void @f1(i32 %a1, i32 %a2) {
 
 define void @g1(i32 %a1, i32 %a2) {
 ;CHECK-APPLE-IOS-LABEL: _g1:
-;CHECK-APPLE-IOS: adrp x8, l__MergedGlobals@PAGE
-;CHECK-APPLE-IOS: add  x8, x8, l__MergedGlobals@PAGEOFF
+;CHECK-APPLE-IOS: adrp x8, __MergedGlobals_x@PAGE
+;CHECK-APPLE-IOS: add  x8, x8, __MergedGlobals_x@PAGEOFF
 ;CHECK-APPLE-IOS-NOT: adrp
   store i32 %a1, i32* @y, align 4
   store i32 %a2, i32* @z, align 4
@@ -41,12 +41,12 @@ define void @g1(i32 %a1, i32 %a2) {
 ;CHECK: z = .L_MergedGlobals+8
 ;CHECK: .size z, 4
 
-;CHECK-APPLE-IOS: .zerofill __DATA,__bss,l__MergedGlobals,12,3
+;CHECK-APPLE-IOS: .zerofill __DATA,__common,__MergedGlobals_x,12,3
 
 ;CHECK-APPLE-IOS: .globl       _x
-;CHECK-APPLE-IOS:  = l__MergedGlobals
+;CHECK-APPLE-IOS:  = __MergedGlobals_x
 ;CHECK-APPLE-IOS: .globl       _y
-;CHECK-APPLE-IOS: _y = l__MergedGlobals+4
+;CHECK-APPLE-IOS: _y = __MergedGlobals_x+4
 ;CHECK-APPLE-IOS: .globl       _z
-;CHECK-APPLE-IOS: _z = l__MergedGlobals+8
+;CHECK-APPLE-IOS: _z = __MergedGlobals_x+8
 ;CHECK-APPLE-IOS: .subsections_via_symbols

diff --git a/llvm/test/CodeGen/AArch64/global-merge-3.ll b/llvm/test/CodeGen/AArch64/global-merge-3.ll
index 0c208a1..6418f01 100644 (file)
--- a/llvm/test/CodeGen/AArch64/global-merge-3.ll
+++ b/llvm/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, l__MergedGlobals@PAGE
+;CHECK-APPLE-IOS: adrp x8, __MergedGlobals_x@PAGE
 ;CHECK-APPLE-IOS-NOT: adrp
-;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
+;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
   %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
@@ -30,11 +30,11 @@ define void @f1(i32 %a1, i32 %a2, i32 %a3) {
 ;CHECK: .comm  .L_MergedGlobals.1,4000,16
 
 ;CHECK-APPLE-IOS: .p2align     4
-;CHECK-APPLE-IOS:  l__MergedGlobals:
+;CHECK-APPLE-IOS:  __MergedGlobals_x:
 ;CHECK-APPLE-IOS: .long 1
 ;CHECK-APPLE-IOS: .space       4000
 
-;CHECK-APPLE-IOS: .zerofill __DATA,__bss,l__MergedGlobals.1,4000,4
+;CHECK-APPLE-IOS: .zerofill __DATA,__common,__MergedGlobals_y,4000,4
 
 ;CHECK: z = .L_MergedGlobals
 ;CHECK:        .globl  x
@@ -44,8 +44,8 @@ define void @f1(i32 %a1, i32 %a2, i32 %a3) {
 ;CHECK: y = .L_MergedGlobals.1
 ;CHECK: .size y, 4000
 
-;CHECK-APPLE-IOS-NOT: _z = l__MergedGlobals
+;CHECK-APPLE-IOS-NOT: _z = __MergedGlobals_x
 ;CHECK-APPLE-IOS:.globl        _x
-;CHECK-APPLE-IOS: _x = l__MergedGlobals+4
+;CHECK-APPLE-IOS: _x = __MergedGlobals_x+4
 ;CHECK-APPLE-IOS:.globl        _y
-;CHECK-APPLE-IOS: _y = l__MergedGlobals.1
+;CHECK-APPLE-IOS: _y = __MergedGlobals_y

diff --git a/llvm/test/CodeGen/AArch64/global-merge-group-by-use.ll b/llvm/test/CodeGen/AArch64/global-merge-group-by-use.ll
index f000db8..86104b7 100644 (file)
--- a/llvm/test/CodeGen/AArch64/global-merge-group-by-use.ll
+++ b/llvm/test/CodeGen/AArch64/global-merge-group-by-use.ll
@@ -13,7 +13,7 @@
 
 ; CHECK-LABEL: f1:
 define void @f1(i32 %a1, i32 %a2) #0 {
-; CHECK-NEXT: adrp x8, [[SET1:l__MergedGlobals.[0-9]*]]@PAGE
+; CHECK-NEXT: adrp x8, [[SET1:__MergedGlobals.[0-9]*]]@PAGE
 ; CHECK-NEXT: add x8, x8, [[SET1]]@PAGEOFF
 ; CHECK-NEXT: stp w0, w1, [x8]
 ; CHECK-NEXT: ret
@@ -28,7 +28,7 @@ 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:l__MergedGlobals.[0-9]*]]@PAGE
+; CHECK-NEXT: adrp x8, [[SET2:__MergedGlobals.[0-9]*]]@PAGE
 ; CHECK-NEXT: add x8, x8, [[SET2]]@PAGEOFF
 ; CHECK-NEXT: stp w0, w1, [x8]
 ; CHECK-NEXT: str w2, [x8, #8]
@@ -49,7 +49,7 @@ 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:l__MergedGlobals[0-9]*]]@PAGE
+; CHECK-NEXT: adrp x9, [[SET3:__MergedGlobals[0-9]*]]@PAGE
 ; CHECK-NEXT: str w0, [x8, _m3@PAGEOFF]
 ; CHECK-NEXT: str w1, [x9, [[SET3]]@PAGEOFF]
 ; CHECK-NEXT: ret

diff --git a/llvm/test/CodeGen/AArch64/global-merge-ignore-single-use-minsize.ll b/llvm/test/CodeGen/AArch64/global-merge-ignore-single-use-minsize.ll
index 28a32f1..1c1b4f6 100644 (file)
--- a/llvm/test/CodeGen/AArch64/global-merge-ignore-single-use-minsize.ll
+++ b/llvm/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:l__MergedGlobals]]@PAGE
+; CHECK-NEXT: adrp x8, [[SET:__MergedGlobals]]@PAGE
 ; CHECK-NEXT: add x8, x8, [[SET]]@PAGEOFF
 ; CHECK-NEXT: stp w0, w1, [x8]
 ; CHECK-NEXT: ret

diff --git a/llvm/test/CodeGen/AArch64/global-merge-ignore-single-use.ll b/llvm/test/CodeGen/AArch64/global-merge-ignore-single-use.ll
index bc7a827..97e283c 100644 (file)
--- a/llvm/test/CodeGen/AArch64/global-merge-ignore-single-use.ll
+++ b/llvm/test/CodeGen/AArch64/global-merge-ignore-single-use.ll
@@ -11,7 +11,7 @@
 
 ; CHECK-LABEL: f1:
 define void @f1(i32 %a1, i32 %a2) #0 {
-; CHECK-NEXT: adrp x8, [[SET:l__MergedGlobals]]@PAGE
+; CHECK-NEXT: adrp x8, [[SET:__MergedGlobals]]@PAGE
 ; CHECK-NEXT: add x8, x8, [[SET]]@PAGEOFF
 ; CHECK-NEXT: stp w0, w1, [x8]
 ; CHECK-NEXT: ret

diff --git a/llvm/test/CodeGen/ARM/2011-06-29-MergeGlobalsAlign.ll b/llvm/test/CodeGen/ARM/2011-06-29-MergeGlobalsAlign.ll
index 1097050..aac8f7b 100644 (file)
--- a/llvm/test/CodeGen/ARM/2011-06-29-MergeGlobalsAlign.ll
+++ b/llvm/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,l__MergedGlobals,16,2
+; CHECK: .zerofill __DATA,__bss,__MergedGlobals,16,2
 
 @prev = external global [0 x i16]
 @max_lazy_match = internal unnamed_addr global i32 0, align 4

diff --git a/llvm/test/CodeGen/ARM/global-merge-1.ll b/llvm/test/CodeGen/ARM/global-merge-1.ll
index a3cbe8a..d4d9b0f 100644 (file)
--- a/llvm/test/CodeGen/ARM/global-merge-1.ll
+++ b/llvm/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,l__MergedGlobals,60,4
+; MERGE: .zerofill __DATA,__bss,__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,l__MergedGlobals,60,4
+; NO-MERGE-NOT: .zerofill __DATA,__bss,__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,l__MergedGlobals,60,4
+; NO-MERGE-NOT: .zerofill __DATA,__bss,__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"