From d19f80a0b4d42258966a57115036cd553d036844 Mon Sep 17 00:00:00 2001 From: Rafael Espindola Date: Mon, 20 Jan 2014 20:33:18 +0000 Subject: Give explicit sections for string constants used in NSStrings. Without them they can be merged with non unnamed_addr constants during LTO. The resulting constant is not unnamed_addr and goes in a different section, which causes ld64 to crash. A testcase that would crash before: * file1.mm: void g(id notification) { [notification valueForKey:@"name"]; } * file2.cpp: extern const char js_name_str[] = "name"; * file3.cpp extern bool JS_GetProperty(const char *name); extern const char js_name_str[]; bool js_ReportUncaughtException() { JS_GetProperty(js_name_str); } run clang file1.mm -o file1.o -c -w -emit-llvm clang file2.cpp -o file2.o -c -w -emit-llvm clang file3.cpp -o file3.o -c -w ld -dylib -o XUL file1.o file2.o file3.o -undefined dynamic_lookup. llvm-svn: 199688 --- clang/lib/CodeGen/CodeGenModule.cpp | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'clang/lib/CodeGen/CodeGenModule.cpp') diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index 88e6e66f9c0..12edab7cd67 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -2396,12 +2396,17 @@ CodeGenModule::GetAddrOfConstantCFString(const StringLiteral *Literal) { GV->setUnnamedAddr(true); // Don't enforce the target's minimum global alignment, since the only use // of the string is via this class initializer. + // FIXME: We set the section explicitly to avoid a bug in ld64 224.1. Without + // it LLVM can merge the string with a non unnamed_addr one during LTO. Doing + // that changes the section it ends in, which surprises ld64. if (isUTF16) { CharUnits Align = getContext().getTypeAlignInChars(getContext().ShortTy); GV->setAlignment(Align.getQuantity()); + GV->setSection("__TEXT,__ustring"); } else { CharUnits Align = getContext().getTypeAlignInChars(getContext().CharTy); GV->setAlignment(Align.getQuantity()); + GV->setSection("__TEXT,__cstring,cstring_literals"); } // String. -- cgit v1.2.3