[llvm] r190096 - Fixed a crash in the integrated assembler for Mach-O when a symbol difference

[Kevin Enderby]

Author: enderby
Date: Thu Sep  5 15:25:06 2013
New Revision: 190096

URL: http://llvm.org/viewvc/llvm-project?rev=190096&view=rev
Log:
Fixed a crash in the integrated assembler for Mach-O when a symbol difference
expression uses an assembler temporary symbol from an assignment.  In this case
the symbol does not have a fragment so the use of getFragment() would be NULL
and caused a crash. In the case of an assembler temporary symbol we want to use
the AliasedSymbol (if any) which will create a local relocation entry, but if
it is not an assembler temporary symbol then let it use that symbol with an
external relocation entry.

rdar://9356266

Added:
    llvm/trunk/test/MC/MachO/darwin-x86_64-diff-reloc-assign-2.s
Modified:
    llvm/trunk/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp

Modified: llvm/trunk/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp?rev=190096&r1=190095&r2=190096&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp (original)
+++ llvm/trunk/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp Thu Sep  5 15:25:06 2013
@@ -144,10 +144,14 @@ void X86MachObjectWriter::RecordX86_64Re
     }
   } else if (Target.getSymB()) { // A - B + constant
     const MCSymbol *A = &Target.getSymA()->getSymbol();
+    if (A->isTemporary())
+      A = &A->AliasedSymbol();
     MCSymbolData &A_SD = Asm.getSymbolData(*A);
     const MCSymbolData *A_Base = Asm.getAtom(&A_SD);
 
     const MCSymbol *B = &Target.getSymB()->getSymbol();
+    if (B->isTemporary())
+      B = &B->AliasedSymbol();
     MCSymbolData &B_SD = Asm.getSymbolData(*B);
     const MCSymbolData *B_Base = Asm.getAtom(&B_SD);
 

Added: llvm/trunk/test/MC/MachO/darwin-x86_64-diff-reloc-assign-2.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/MachO/darwin-x86_64-diff-reloc-assign-2.s?rev=190096&view=auto
==============================================================================
--- llvm/trunk/test/MC/MachO/darwin-x86_64-diff-reloc-assign-2.s (added)
+++ llvm/trunk/test/MC/MachO/darwin-x86_64-diff-reloc-assign-2.s Thu Sep  5 15:25:06 2013
@@ -0,0 +1,38 @@
+// RUN: llvm-mc -triple x86_64-apple-darwin9 %s -filetype=obj -o - | macho-dump --dump-section-data | FileCheck %s
+
+// Test case for rdar://9356266
+
+// This tests that this expression does not cause a crash and produces these
+// four relocation entries:
+// Relocation information (__DATA,__data) 4 entries
+// address  pcrel length extern type    scattered symbolnum/value
+// 00000004 False long   False  SUB     False     2 (__DATA,__data)
+// 00000004 False long   False  UNSIGND False     2 (__DATA,__data)
+// 00000000 False long   False  SUB     False     2 (__DATA,__data)
+// 00000000 False long   False  UNSIGND False     2 (__DATA,__data)
+
+	.data
+L_var1:
+L_var2:
+// This was working fine
+	.long L_var2 - L_var1
+	
+	.set L_var3, .
+	.set L_var4, .
+// But this was causing a crash
+	.long L_var4 - L_var3
+
+// CHECK:  ('_relocations', [
+// CHECK:    # Relocation 0
+// CHECK:    (('word-0', 0x4),
+// CHECK:     ('word-1', 0x54000002)),
+// CHECK:    # Relocation 1
+// CHECK:    (('word-0', 0x4),
+// CHECK:     ('word-1', 0x4000002)),
+// CHECK:    # Relocation 2
+// CHECK:    (('word-0', 0x0),
+// CHECK:     ('word-1', 0x54000002)),
+// CHECK:    # Relocation 3
+// CHECK:    (('word-0', 0x0),
+// CHECK:     ('word-1', 0x4000002)),
+// CHECK:  ])