From: Kevin Enderby <enderby@apple.com>
Date: Thu, 5 Sep 2013 20:25:06 +0000 (+0000)
Subject: Fixed a crash in the integrated assembler for Mach-O when a symbol difference
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d8e2f1757d9ececd7937406596fec8e4ebfb7d46;p=oota-llvm.git

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


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190096 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp b/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp
index b6f10ba9945..eb7c0b1a996 100644
--- a/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp
+++ b/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp
@@ -144,10 +144,14 @@ void X86MachObjectWriter::RecordX86_64Relocation(MachObjectWriter *Writer,
     }
   } 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);
 
diff --git a/test/MC/MachO/darwin-x86_64-diff-reloc-assign-2.s b/test/MC/MachO/darwin-x86_64-diff-reloc-assign-2.s
new file mode 100644
index 00000000000..5d548790a7a
--- /dev/null
+++ b/test/MC/MachO/darwin-x86_64-diff-reloc-assign-2.s
@@ -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:  ])