r199688 - Give explicit sections for string constants used in NSStrings.

Rafael Espindola rafael.espindola at gmail.com
Mon Jan 20 12:33:18 PST 2014 

Author: rafael
Date: Mon Jan 20 14:33:18 2014
New Revision: 199688

URL: http://llvm.org/viewvc/llvm-project?rev=199688&view=rev
Log:
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.

Modified:
    cfe/trunk/lib/CodeGen/CodeGenModule.cpp
    cfe/trunk/test/CodeGen/cfstring.c
    cfe/trunk/test/CodeGen/darwin-string-literals.c
    cfe/trunk/test/CodeGen/utf16-cfstrings.c
    cfe/trunk/test/CodeGenObjC/2009-08-05-utf16.m
    cfe/trunk/test/CodeGenObjC/2010-02-01-utf16-with-null.m
    cfe/trunk/test/CodeGenObjC/constant-strings.m

Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=199688&r1=199687&r2=199688&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Mon Jan 20 14:33:18 2014
@@ -2396,12 +2396,17 @@ CodeGenModule::GetAddrOfConstantCFString
   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.

Modified: cfe/trunk/test/CodeGen/cfstring.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/cfstring.c?rev=199688&r1=199687&r2=199688&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/cfstring.c (original)
+++ cfe/trunk/test/CodeGen/cfstring.c Mon Jan 20 14:33:18 2014
@@ -5,9 +5,9 @@
 //
 // RUN: %clang_cc1 -fwritable-strings -emit-llvm %s -o - | FileCheck %s
 //
-// CHECK: @.str = linker_private unnamed_addr constant [14 x i8] c"Hello, World!\00", align 1
-// CHECK: @.str1 = linker_private unnamed_addr constant [7 x i8] c"yo joe\00", align 1
-// CHECK: @.str3 = linker_private unnamed_addr constant [16 x i8] c"Goodbye, World!\00", align 1
+// CHECK: @.str = linker_private unnamed_addr constant [14 x i8] c"Hello, World!\00", section "__TEXT,__cstring,cstring_literals", align 1
+// CHECK: @.str1 = linker_private unnamed_addr constant [7 x i8] c"yo joe\00", section "__TEXT,__cstring,cstring_literals", align 1
+// CHECK: @.str3 = linker_private unnamed_addr constant [16 x i8] c"Goodbye, World!\00", section "__TEXT,__cstring,cstring_literals", align 1
 
 #define CFSTR __builtin___CFStringMakeConstantString
 

Modified: cfe/trunk/test/CodeGen/darwin-string-literals.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/darwin-string-literals.c?rev=199688&r1=199687&r2=199688&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/darwin-string-literals.c (original)
+++ cfe/trunk/test/CodeGen/darwin-string-literals.c Mon Jan 20 14:33:18 2014
@@ -2,16 +2,16 @@
 
 // CHECK-LSB: @.str = private unnamed_addr constant [8 x i8] c"string0\00"
 // CHECK-LSB: @.str1 = linker_private unnamed_addr constant [8 x i8] c"string1\00"
-// CHECK-LSB: @.str2 = internal unnamed_addr constant [18 x i16] [i16 104, i16 101, i16 108, i16 108, i16 111, i16 32, i16 8594, i16 32, i16 9731, i16 32, i16 8592, i16 32, i16 119, i16 111, i16 114, i16 108, i16 100, i16 0], align 2
-// CHECK-LSB: @.str4 = internal unnamed_addr constant [6 x i16] [i16 116, i16 101, i16 115, i16 116, i16 8482, i16 0], align 2
+// CHECK-LSB: @.str2 = internal unnamed_addr constant [18 x i16] [i16 104, i16 101, i16 108, i16 108, i16 111, i16 32, i16 8594, i16 32, i16 9731, i16 32, i16 8592, i16 32, i16 119, i16 111, i16 114, i16 108, i16 100, i16 0], section "__TEXT,__ustring", align 2
+// CHECK-LSB: @.str4 = internal unnamed_addr constant [6 x i16] [i16 116, i16 101, i16 115, i16 116, i16 8482, i16 0], section "__TEXT,__ustring", align 2
 
 
 // RUN: %clang_cc1 -triple powerpc-apple-darwin9 -emit-llvm %s -o - | FileCheck -check-prefix CHECK-MSB %s
 
 // CHECK-MSB: @.str = private unnamed_addr constant [8 x i8] c"string0\00"
 // CHECK-MSB: @.str1 = linker_private unnamed_addr constant [8 x i8] c"string1\00"
-// CHECK-MSB: @.str2 = internal unnamed_addr constant [18 x i16] [i16 104, i16 101, i16 108, i16 108, i16 111, i16 32, i16 8594, i16 32, i16 9731, i16 32, i16 8592, i16 32, i16 119, i16 111, i16 114, i16 108, i16 100, i16 0], align 2
-// CHECK-MSB: @.str4 = internal unnamed_addr constant [6 x i16] [i16 116, i16 101, i16 115, i16 116, i16 8482, i16 0], align 2
+// CHECK-MSB: @.str2 = internal unnamed_addr constant [18 x i16] [i16 104, i16 101, i16 108, i16 108, i16 111, i16 32, i16 8594, i16 32, i16 9731, i16 32, i16 8592, i16 32, i16 119, i16 111, i16 114, i16 108, i16 100, i16 0], section "__TEXT,__ustring", align 2
+// CHECK-MSB: @.str4 = internal unnamed_addr constant [6 x i16] [i16 116, i16 101, i16 115, i16 116, i16 8482, i16 0], section "__TEXT,__ustring", align 2
 
 const char *g0 = "string0";
 const void *g1 = __builtin___CFStringMakeConstantString("string1");

Modified: cfe/trunk/test/CodeGen/utf16-cfstrings.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/utf16-cfstrings.c?rev=199688&r1=199687&r2=199688&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/utf16-cfstrings.c (original)
+++ cfe/trunk/test/CodeGen/utf16-cfstrings.c Mon Jan 20 14:33:18 2014
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -triple x86_64-apple-darwin -emit-llvm %s -o - | FileCheck %s
 // <rdar://problem/10655949>
 
-// CHECK: @.str = internal unnamed_addr constant [9 x i16] [i16 252, i16 98, i16 101, i16 114, i16 104, i16 117, i16 110, i16 100, i16 0], align 2
+// CHECK: @.str = internal unnamed_addr constant [9 x i16] [i16 252, i16 98, i16 101, i16 114, i16 104, i16 117, i16 110, i16 100, i16 0], section "__TEXT,__ustring", align 2
 
 #define CFSTR __builtin___CFStringMakeConstantString
 

Modified: cfe/trunk/test/CodeGenObjC/2009-08-05-utf16.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/2009-08-05-utf16.m?rev=199688&r1=199687&r2=199688&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenObjC/2009-08-05-utf16.m (original)
+++ cfe/trunk/test/CodeGenObjC/2009-08-05-utf16.m Mon Jan 20 14:33:18 2014
@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -emit-llvm -w -x objective-c %s -o - | FileCheck %s
 // rdar://7095855 rdar://7115749
 
-// CHECK: internal unnamed_addr constant [6 x i16] [i16 105, i16 80, i16 111, i16 100, i16 8482, i16 0], align 2
+// CHECK: internal unnamed_addr constant [6 x i16] [i16 105, i16 80, i16 111, i16 100, i16 8482, i16 0], section "__TEXT,__ustring", align 2
 void *P = @"iPod™";

Modified: cfe/trunk/test/CodeGenObjC/2010-02-01-utf16-with-null.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/2010-02-01-utf16-with-null.m?rev=199688&r1=199687&r2=199688&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenObjC/2010-02-01-utf16-with-null.m (original)
+++ cfe/trunk/test/CodeGenObjC/2010-02-01-utf16-with-null.m Mon Jan 20 14:33:18 2014
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -triple i686-apple-darwin -emit-llvm %s -o - | FileCheck %s
 // rdar://7589850
 
-// CHECK: @.str = internal unnamed_addr constant [9 x i16] [i16 103, i16 111, i16 111, i16 100, i16 0, i16 98, i16 121, i16 101, i16 0], align 2
+// CHECK: @.str = internal unnamed_addr constant [9 x i16] [i16 103, i16 111, i16 111, i16 100, i16 0, i16 98, i16 121, i16 101, i16 0], section "__TEXT,__ustring", align 2
 // CHECK: @_unnamed_cfstring_ = private constant %struct.NSConstantString { i32* getelementptr inbounds ([0 x i32]* @__CFConstantStringClassReference, i32 0, i32 0), i32 2000, i8* bitcast ([9 x i16]* @.str to i8*), i32 8 }, section "__DATA,__cfstring"
 // CHECK: @P = global i8* bitcast (%struct.NSConstantString* @_unnamed_cfstring_ to i8*), align 4
 void *P = @"good\0bye";

Modified: cfe/trunk/test/CodeGenObjC/constant-strings.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/constant-strings.m?rev=199688&r1=199687&r2=199688&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenObjC/constant-strings.m (original)
+++ cfe/trunk/test/CodeGenObjC/constant-strings.m Mon Jan 20 14:33:18 2014
@@ -3,7 +3,7 @@
 
 // Check that we set alignment 1 on the string.
 //
-// CHECK-NEXT: @.str = {{.*}}constant [13 x i8] c"Hello World!\00", align 1
+// CHECK-NEXT: @.str = {{.*}}constant [13 x i8] c"Hello World!\00", section "__TEXT,__cstring,cstring_literals", align 1
 
 // RUN: %clang_cc1 -fobjc-runtime=gcc -emit-llvm -o %t %s
 // RUN: FileCheck --check-prefix=CHECK-GNU < %t %s

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