Introducing external weak linkage. Darwin codegen should be added later.
llvm-svn: 32052
diff --git a/llvm/lib/Target/CBackend/Writer.cpp b/llvm/lib/Target/CBackend/Writer.cpp
index fa869db..6d83aeb 100644
--- a/llvm/lib/Target/CBackend/Writer.cpp
+++ b/llvm/lib/Target/CBackend/Writer.cpp
@@ -1157,8 +1157,6 @@
<< "#define __attribute__(X)\n"
<< "#endif\n\n";
-#if 0
- // At some point, we should support "external weak" vs. "weak" linkages.
// On Mac OS X, "external weak" is spelled "__attribute__((weak_import))".
Out << "#if defined(__GNUC__) && defined(__APPLE_CC__)\n"
<< "#define __EXTERNAL_WEAK__ __attribute__((weak_import))\n"
@@ -1167,7 +1165,6 @@
<< "#else\n"
<< "#define __EXTERNAL_WEAK__\n"
<< "#endif\n\n";
-#endif
// For now, turn off the weak linkage attribute on Mac OS X. (See above.)
Out << "#if defined(__GNUC__) && defined(__APPLE_CC__)\n"
@@ -1357,7 +1354,11 @@
Out << "__declspec(dllimport) ";
printType(Out, I->getType()->getElementType(), Mang->getValueName(I));
Out << ";\n";
- }
+ } else if (I->hasExternalWeakLinkage()) {
+ Out << "extern ";
+ printType(Out, I->getType()->getElementType(), Mang->getValueName(I));
+ Out << " __EXTERNAL_WEAK__ ;\n";
+ }
}
}
@@ -1370,9 +1371,13 @@
// Don't print declarations for intrinsic functions.
if (!I->getIntrinsicID() && I->getName() != "setjmp" &&
I->getName() != "longjmp" && I->getName() != "_setjmp") {
+ if (I->hasExternalWeakLinkage())
+ Out << "extern ";
printFunctionSignature(I, true);
if (I->hasWeakLinkage() || I->hasLinkOnceLinkage())
Out << " __ATTRIBUTE_WEAK__";
+ if (I->hasExternalWeakLinkage())
+ Out << " __EXTERNAL_WEAK__";
if (StaticCtors.count(I))
Out << " __ATTRIBUTE_CTOR__";
if (StaticDtors.count(I))
@@ -1405,6 +1410,8 @@
Out << " __attribute__((common))";
else if (I->hasWeakLinkage())
Out << " __ATTRIBUTE_WEAK__";
+ else if (I->hasExternalWeakLinkage())
+ Out << " __EXTERNAL_WEAK__";
Out << ";\n";
}
}
diff --git a/llvm/lib/Target/X86/X86ATTAsmPrinter.cpp b/llvm/lib/Target/X86/X86ATTAsmPrinter.cpp
index 7784f62..88d0c7c 100755
--- a/llvm/lib/Target/X86/X86ATTAsmPrinter.cpp
+++ b/llvm/lib/Target/X86/X86ATTAsmPrinter.cpp
@@ -255,6 +255,10 @@
}
O << Name;
}
+
+ if (GV->hasExternalWeakLinkage()) {
+ ExtWeakSymbols.insert(Name);
+ }
int Offset = MO.getOffset();
if (Offset > 0)
diff --git a/llvm/lib/Target/X86/X86AsmPrinter.cpp b/llvm/lib/Target/X86/X86AsmPrinter.cpp
index 2c53b72..cb792ad 100644
--- a/llvm/lib/Target/X86/X86AsmPrinter.cpp
+++ b/llvm/lib/Target/X86/X86AsmPrinter.cpp
@@ -128,11 +128,12 @@
// from how MASM does things. When making changes here don't forget to look
// at X86IntelAsmPrinter::doFinalization().
const TargetData *TD = TM.getTargetData();
-
+
// Print out module-level global variables here.
for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
I != E; ++I) {
- if (!I->hasInitializer()) continue; // External global require no code
+ if (!I->hasInitializer() && !I->hasExternalWeakLinkage())
+ continue; // External global require no code
// Check to see if this is a special global used by LLVM, if so, emit it.
if (EmitSpecialLLVMGlobal(I))
@@ -176,6 +177,17 @@
O << "\t\t" << TAI->getCommentString() << " " << I->getName() << "\n";
} else {
switch (I->getLinkage()) {
+ case GlobalValue::ExternalWeakLinkage:
+ if (Subtarget->isTargetDarwin()) {
+ assert(0 && "External weak linkage for Darwin not implemented yet");
+ } else if (Subtarget->isTargetCygwin()) {
+ // There is no external weak linkage on Mingw32 platform.
+ // Defaulting just to external
+ O << "\t.globl " << name << "\n";
+ } else {
+ O << "\t.weak " << name << "\n";
+ break;
+ }
case GlobalValue::LinkOnceLinkage:
case GlobalValue::WeakLinkage:
if (Subtarget->isTargetDarwin()) {
@@ -270,7 +282,24 @@
i != e; ++i) {
O << "\t.ascii \" -export:" << *i << "\"\n";
}
-
+
+ if (Subtarget->isTargetDarwin()) {
+ if (ExtWeakSymbols.begin() != ExtWeakSymbols.end())
+ assert(0 && "External weak linkage for Darwin not implemented yet");
+ } else if (Subtarget->isTargetCygwin()) {
+ // There is no external weak linkage on Mingw32 platform.
+ // Defaulting to external
+ } else {
+ if (ExtWeakSymbols.begin() != ExtWeakSymbols.end())
+ SwitchToDataSection("");
+
+ for (std::set<std::string>::iterator i = ExtWeakSymbols.begin(),
+ e = ExtWeakSymbols.end();
+ i != e; ++i) {
+ O << "\t.weak " << *i << "\n";
+ }
+ }
+
if (Subtarget->isTargetDarwin()) {
SwitchToDataSection("");
diff --git a/llvm/lib/Target/X86/X86AsmPrinter.h b/llvm/lib/Target/X86/X86AsmPrinter.h
index 3503e37..8dad733 100755
--- a/llvm/lib/Target/X86/X86AsmPrinter.h
+++ b/llvm/lib/Target/X86/X86AsmPrinter.h
@@ -84,6 +84,9 @@
// Necessary for dllexport support
std::set<std::string> DLLExportedFns, DLLExportedGVs;
+
+ // Necessary for external weak linkage support
+ std::set<std::string> ExtWeakSymbols;
inline static bool isScale(const MachineOperand &MO) {
return MO.isImmediate() &&