[PATCH] Use proper section suffix for COFF weak symbols
Nico Rieck
nico.rieck at gmail.com
Wed Jul 17 15:50:29 PDT 2013
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.
I've updated the existing test case to emit assembly instead. Should the test be moved to CodeGen (or even to a subdirectory there)?
http://llvm-reviews.chandlerc.com/D1173
Files:
include/llvm/Target/Mangler.h
lib/CodeGen/TargetLoweringObjectFileImpl.cpp
lib/Target/Mangler.cpp
test/MC/COFF/weak-symbol-section-specification.ll
test/MC/COFF/weak-symbol.ll
Index: include/llvm/Target/Mangler.h
===================================================================
--- include/llvm/Target/Mangler.h
+++ include/llvm/Target/Mangler.h
@@ -59,13 +59,14 @@
/// 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
Index: lib/CodeGen/TargetLoweringObjectFileImpl.cpp
===================================================================
--- lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -726,9 +726,8 @@
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 @@
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);
Index: lib/Target/Mangler.cpp
===================================================================
--- lib/Target/Mangler.cpp
+++ lib/Target/Mangler.cpp
@@ -105,7 +105,8 @@
/// 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 @@
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 @@
/// 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 @@
// 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 @@
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,
Index: test/MC/COFF/weak-symbol-section-specification.ll
===================================================================
--- 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
-
- at 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: )
Index: test/MC/COFF/weak-symbol.ll
===================================================================
--- /dev/null
+++ 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
+ at a = weak unnamed_addr constant { i32, i32, i32 } { i32 0, i32 0, i32 0}, section ".data"
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