Fix PR18743.

The IR
@foo = private constant i32 42

is valid, but before this patch we would produce an invalid MachO from it. It
was invalid because it would use an L label in a section where the liker needs
the labels in order to atomize it.

One way of fixing it would be to just reject this IR in the backend, but that
would not be very front end friendly.

What this patch does is use an 'l' prefix in sections that we know the linker
requires symbols for atomizing them. This allows frontends to just use
private and not worry about which sections they go to or how the linker handles
them.

One small issue with this strategy is that now a symbol name depends on the
section, which is not available before codegen. This is not a problem in
practice. The reason is that it only happens with private linkage, which will
be ignored by the non codegen users (llvm-nm and llvm-ar).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201608 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 4 deletions

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 63b4bb4296..6c4cddc3f6 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -311,8 +311,13 @@ void AsmPrinter::EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const {
   llvm_unreachable("Unknown linkage type!");
 }
 
+void AsmPrinter::getNameWithPrefix(SmallVectorImpl<char> &Name,
+                                   const GlobalValue *GV) const {
+  TM.getTargetLowering()->getNameWithPrefix(Name, GV, *Mang);
+}
+
 MCSymbol *AsmPrinter::getSymbol(const GlobalValue *GV) const {
-  return getObjFileLowering().getSymbol(GV, *Mang);
+  return TM.getTargetLowering()->getSymbol(GV, *Mang);
 }
 
 /// EmitGlobalVariable - Emit the specified global variable to the .s file.
@@ -1369,7 +1374,7 @@ void AsmPrinter::EmitLLVMUsedList(const ConstantArray *InitList) {
   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
     const GlobalValue *GV =
       dyn_cast<GlobalValue>(InitList->getOperand(i)->stripPointerCasts());
-    if (GV && getObjFileLowering().shouldEmitUsedDirectiveFor(GV, *Mang))
+    if (GV && getObjFileLowering().shouldEmitUsedDirectiveFor(GV, *Mang, TM))
       OutStreamer.EmitSymbolAttribute(getSymbol(GV), MCSA_NoDeadStrip);
   }
 }
@@ -1574,7 +1579,8 @@ static const MCExpr *lowerConstant(const Constant *CV, AsmPrinter &AP) {
   }
 
   if (const MCExpr *RelocExpr =
-          AP.getObjFileLowering().getExecutableRelativeSymbol(CE, *AP.Mang))
+          AP.getObjFileLowering().getExecutableRelativeSymbol(CE, *AP.Mang,
+                                                              AP.TM))
     return RelocExpr;
 
   switch (CE->getOpcode()) {
@@ -2103,7 +2109,8 @@ MCSymbol *AsmPrinter::GetJTSetSymbol(unsigned UID, unsigned MBBID) const {
 
 MCSymbol *AsmPrinter::getSymbolWithGlobalValueBase(const GlobalValue *GV,
                                                    StringRef Suffix) const {
-  return getObjFileLowering().getSymbolWithGlobalValueBase(GV, Suffix, *Mang);
+  return getObjFileLowering().getSymbolWithGlobalValueBase(GV, Suffix, *Mang,
+                                                           TM);
 }
 
 /// GetExternalSymbolSymbol - Return the MCSymbol for the specified