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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286607 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/GlobalMerge.cpp b/lib/CodeGen/GlobalMerge.cpp
index 2d9e0938fead173ed200e7114dffa26cffa26696..e0ffd475e64647d964466a23f03e4c81ff32add0 100644 (file)
--- a/lib/CodeGen/GlobalMerge.cpp
+++ b/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/test/CodeGen/AArch64/global-merge-1.ll b/test/CodeGen/AArch64/global-merge-1.ll
index 6c9b3cbcd6df43f49cdd1970003df90f0f538c3f..b5a28a18718c43f8882e189e611f4bbfabed42fa 100644 (file)
--- a/test/CodeGen/AArch64/global-merge-1.ll
+++ b/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/test/CodeGen/AArch64/global-merge-2.ll b/test/CodeGen/AArch64/global-merge-2.ll
index 10f3a948dc7afbe78f7badcc7b83a74f7895f752..6cd3f5580438c3e8ee1d2e524f9490b340ace26a 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, 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/test/CodeGen/AArch64/global-merge-3.ll b/test/CodeGen/AArch64/global-merge-3.ll
index 0c208a166418efa32e908756d712489ee486e894..6418f019f7476024d75cbd49dcea6f3e3610c979 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, 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/test/CodeGen/AArch64/global-merge-group-by-use.ll b/test/CodeGen/AArch64/global-merge-group-by-use.ll
index f000db8587b67d0b5238a8219f540549bc6de5ca..86104b7285cfdcd369a50bfecf08c11062a7ee55 100644 (file)
--- a/test/CodeGen/AArch64/global-merge-group-by-use.ll
+++ b/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/test/CodeGen/AArch64/global-merge-ignore-single-use-minsize.ll b/test/CodeGen/AArch64/global-merge-ignore-single-use-minsize.ll
index 28a32f148f17c34a64ff2fdfbf083c9cdd04ded3..1c1b4f6b0452774aa4929b84171909cda862c29d 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: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/test/CodeGen/AArch64/global-merge-ignore-single-use.ll b/test/CodeGen/AArch64/global-merge-ignore-single-use.ll
index bc7a8274cbf8216ab01950ec3eab41a628b37ce0..97e283c972a549227f31c352d7c5a831ae9030c1 100644 (file)
--- a/test/CodeGen/AArch64/global-merge-ignore-single-use.ll
+++ b/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/test/CodeGen/ARM/2011-06-29-MergeGlobalsAlign.ll b/test/CodeGen/ARM/2011-06-29-MergeGlobalsAlign.ll
index 1097050df54b3516f67d5c973723641772df2464..aac8f7b3a026b9e22ae5c30929c52ca97be759ff 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,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/test/CodeGen/ARM/global-merge-1.ll b/test/CodeGen/ARM/global-merge-1.ll
index a3cbe8aec0984f51fb4fbfe45737f68770d5f30d..d4d9b0f9d1f3e90f333f7fab9d8b3044b9c28da3 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,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"