Use proper section suffix for COFF weak symbols

32-bit symbols have "_" as global prefix, but when forming the name of
COMDAT sections this prefix is ignored. The current behavior assumes that
this prefix is always present which is not the case for 64-bit and names
are truncated.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187356 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 66 insertions, 43 deletions

diff --git a/include/llvm/Target/Mangler.h b/include/llvm/Target/Mangler.h
index 986244f..e925cd5 100644
--- a/include/llvm/Target/Mangler.h
+++ b/include/llvm/Target/Mangler.h
@@ -59,13 +59,14 @@ public:
   /// and the specified global variable's name.  If the global variable doesn't
   /// have a name, this fills in a unique name for the global.
   void getNameWithPrefix(SmallVectorImpl<char> &OutName, const GlobalValue *GV,
-                         bool isImplicitlyPrivate);
+                         bool isImplicitlyPrivate, bool UseGlobalPrefix = true);
 
   /// getNameWithPrefix - Fill OutName with the name of the appropriate prefix
   /// and the specified name as the global variable name.  GVName must not be
   /// empty.
   void getNameWithPrefix(SmallVectorImpl<char> &OutName, const Twine &GVName,
-                         ManglerPrefixTy PrefixTy = Mangler::Default);
+                         ManglerPrefixTy PrefixTy = Mangler::Default,
+                         bool UseGlobalPrefix = true);
 };
 
 } // End llvm namespace
diff --git a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 3e1afc0..07cf871 100644
--- a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -726,9 +726,8 @@ getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
   if (GV->isWeakForLinker()) {
     Selection = COFF::IMAGE_COMDAT_SELECT_ANY;
     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
-    MCSymbol *Sym = Mang->getSymbol(GV);
     Name.append("$");
-    Name.append(Sym->getName().begin() + 1, Sym->getName().end());
+    Mang->getNameWithPrefix(Name, GV, false, false);
   }
   return getContext().getCOFFSection(Name,
                                      Characteristics,
@@ -761,8 +760,7 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
   if (GV->isWeakForLinker()) {
     const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
-    MCSymbol *Sym = Mang->getSymbol(GV);
-    Name.append(Sym->getName().begin() + 1, Sym->getName().end());
+    Mang->getNameWithPrefix(Name, GV, false, false);
 
     unsigned Characteristics = getCOFFSectionFlags(Kind);
 
diff --git a/lib/Target/Mangler.cpp b/lib/Target/Mangler.cpp
index dc70259..f86428c 100644
--- a/lib/Target/Mangler.cpp
+++ b/lib/Target/Mangler.cpp
@@ -105,7 +105,8 @@ static void appendMangledQuotedName(SmallVectorImpl<char> &OutName,
 /// and the specified name as the global variable name.  GVName must not be
 /// empty.
 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
-                                const Twine &GVName, ManglerPrefixTy PrefixTy) {
+                                const Twine &GVName, ManglerPrefixTy PrefixTy,
+                                bool UseGlobalPrefix) {
   SmallString<256> TmpData;
   StringRef Name = GVName.toStringRef(TmpData);
   assert(!Name.empty() && "getNameWithPrefix requires non-empty name");
@@ -124,13 +125,16 @@ void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
       OutName.append(Prefix, Prefix+strlen(Prefix));
     }
 
-    const char *Prefix = MAI->getGlobalPrefix();
-    if (Prefix[0] == 0)
-      ; // Common noop, no prefix.
-    else if (Prefix[1] == 0)
-      OutName.push_back(Prefix[0]);  // Common, one character prefix.
-    else
-      OutName.append(Prefix, Prefix+strlen(Prefix)); // Arbitrary length prefix.
+    if (UseGlobalPrefix) {
+      const char *Prefix = MAI->getGlobalPrefix();
+      if (Prefix[0] == 0)
+        ; // Common noop, no prefix.
+      else if (Prefix[1] == 0)
+        OutName.push_back(Prefix[0]);  // Common, one character prefix.
+      else
+        // Arbitrary length prefix.
+        OutName.append(Prefix, Prefix+strlen(Prefix));
+    }
   }
   
   // If this is a simple string that doesn't need escaping, just append it.
@@ -179,8 +183,8 @@ static void AddFastCallStdCallSuffix(SmallVectorImpl<char> &OutName,
 /// and the specified global variable's name.  If the global variable doesn't
 /// have a name, this fills in a unique name for the global.
 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
-                                const GlobalValue *GV,
-                                bool isImplicitlyPrivate) {
+                                const GlobalValue *GV, bool isImplicitlyPrivate,
+                                bool UseGlobalPrefix) {
   ManglerPrefixTy PrefixTy = Mangler::Default;
   if (GV->hasPrivateLinkage() || isImplicitlyPrivate)
     PrefixTy = Mangler::Private;
@@ -190,7 +194,7 @@ void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
   // If this global has a name, handle it simply.
   if (GV->hasName()) {
     StringRef Name = GV->getName();
-    getNameWithPrefix(OutName, Name, PrefixTy);
+    getNameWithPrefix(OutName, Name, PrefixTy, UseGlobalPrefix);
     // No need to do anything else if the global has the special "do not mangle"
     // flag in the name.
     if (Name[0] == 1)
@@ -202,7 +206,8 @@ void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
     if (ID == 0) ID = NextAnonGlobalID++;
   
     // Must mangle the global into a unique ID.
-    getNameWithPrefix(OutName, "__unnamed_" + Twine(ID), PrefixTy);
+    getNameWithPrefix(OutName, "__unnamed_" + Twine(ID), PrefixTy,
+                      UseGlobalPrefix);
   }
   
   // If we are supposed to add a microsoft-style suffix for stdcall/fastcall,
diff --git a/test/MC/COFF/weak-symbol-section-specification.ll b/test/MC/COFF/weak-symbol-section-specification.ll
deleted file mode 100644
index 4772c92..0000000
--- a/test/MC/COFF/weak-symbol-section-specification.ll
+++ /dev/null
@@ -1,25 +0,0 @@
-; The purpose of this test is to verify that weak linkage type is not ignored by backend,
-; if section was specialized.
-
-; RUN: llc -filetype=obj -mtriple i686-pc-win32 %s -o - | llvm-readobj -s -sd | FileCheck %s
-
-@a = weak unnamed_addr constant { i32, i32, i32 } { i32 0, i32 0, i32 0}, section ".data"
-
-; CHECK:           Name:                      .data$a
-; CHECK-NEXT:      VirtualSize:               0
-; CHECK-NEXT:      VirtualAddress:            0
-; CHECK-NEXT:      RawDataSize:               {{[0-9]+}}
-; CHECK-NEXT:      PointerToRawData:          0x{{[0-9A-F]+}}
-; CHECK-NEXT:      PointerToRelocations:      0x0
-; CHECK-NEXT:      PointerToLineNumbers:      0x0
-; CHECK-NEXT:      RelocationCount:           0
-; CHECK-NEXT:      LineNumberCount:           0
-; CHECK-NEXT:      Characteristics [ (0x40401040)
-; CHECK-NEXT:        IMAGE_SCN_ALIGN_8BYTES
-; CHECK-NEXT:        IMAGE_SCN_CNT_INITIALIZED_DATA
-; CHECK-NEXT:        IMAGE_SCN_LNK_COMDAT
-; CHECK-NEXT:        IMAGE_SCN_MEM_READ
-; CHECK-NEXT:      ]
-; CHECK-NEXT:      SectionData (
-; CHECK-NEXT:        0000: 00000000 00000000 00000000
-; CHECK-NEXT:      )
diff --git a/test/MC/COFF/weak-symbol.ll b/test/MC/COFF/weak-symbol.ll
new file mode 100644
index 0000000..7f2e87c
--- /dev/null
+++ b/test/MC/COFF/weak-symbol.ll
@@ -0,0 +1,44 @@
+; Test that weak functions and globals are placed into selectany COMDAT

+; sections with the mangled name as suffix. Ensure that the weak linkage

+; type is not ignored by the backend if the section was specialized.

+;

+; RUN: llc -mtriple=i686-pc-win32 %s     -o - | FileCheck %s --check-prefix=X86

+; RUN: llc -mtriple=i686-pc-mingw32 %s   -o - | FileCheck %s --check-prefix=X86

+; RUN: llc -mtriple=x86_64-pc-win32 %s   -o - | FileCheck %s --check-prefix=X64

+; RUN: llc -mtriple=x86_64-pc-mingw32 %s -o - | FileCheck %s --check-prefix=X64

+

+; Mangled function

+; X86: .section .text$_Z3foo

+; X86: .linkonce discard

+; X86: .globl __Z3foo

+;

+; X64: .section .text$_Z3foo

+; X64: .linkonce discard

+; X64: .globl _Z3foo

+define weak void @_Z3foo() {

+  ret void

+}

+

+; Unmangled function

+; X86: .section .sect$f

+; X86: .linkonce discard

+; X86: .globl _f

+;

+; X64: .section .sect$f

+; X64: .linkonce discard

+; X64: .globl f

+define weak void @f() section ".sect" {

+  ret void

+}

+

+; Weak global

+; X86: .section .data$a

+; X86: .linkonce discard

+; X86: .globl _a

+; X86: .zero 12

+;

+; X64: .section .data$a

+; X64: .linkonce discard

+; X64: .globl a

+; X64: .zero 12

+@a = weak unnamed_addr constant { i32, i32, i32 } { i32 0, i32 0, i32 0}, section ".data"