[llvm] r228565 - MC: Calculate intra-section symbol differences correctly for COFF

[David Majnemer]

Author: majnemer
Date: Mon Feb  9 00:31:31 2015
New Revision: 228565

URL: http://llvm.org/viewvc/llvm-project?rev=228565&view=rev
Log:
MC: Calculate intra-section symbol differences correctly for COFF

This fixes PR22060.

Modified:
    llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp
    llvm/trunk/test/MC/COFF/diff.s

Modified: llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp?rev=228565&r1=228564&r2=228565&view=diff
==============================================================================
--- llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp (original)
+++ llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp Mon Feb  9 00:31:31 2015
@@ -706,17 +706,22 @@ void WinCOFFObjectWriter::RecordRelocati
     CrossSection = &Symbol.getSection() != &B->getSection();
 
     // Offset of the symbol in the section
-    int64_t a = Layout.getSymbolOffset(&B_SD);
+    int64_t OffsetOfB = Layout.getSymbolOffset(&B_SD);
 
-    // Offset of the relocation in the section
-    int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
-
-    FixedValue = b - a;
     // In the case where we have SymbA and SymB, we just need to store the delta
     // between the two symbols.  Update FixedValue to account for the delta, and
     // skip recording the relocation.
-    if (!CrossSection)
+    if (!CrossSection) {
+      int64_t OffsetOfA = Layout.getSymbolOffset(&A_SD);
+      FixedValue = (OffsetOfA - OffsetOfB) + Target.getConstant();
       return;
+    }
+
+    // Offset of the relocation in the section
+    int64_t OffsetOfRelocation =
+        Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
+
+    FixedValue = OffsetOfRelocation - OffsetOfB;
   } else {
     FixedValue = Target.getConstant();
   }

Modified: llvm/trunk/test/MC/COFF/diff.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/COFF/diff.s?rev=228565&r1=228564&r2=228565&view=diff
==============================================================================
--- llvm/trunk/test/MC/COFF/diff.s (original)
+++ llvm/trunk/test/MC/COFF/diff.s Mon Feb  9 00:31:31 2015
@@ -1,5 +1,23 @@
 // RUN: llvm-mc -filetype=obj -triple i686-pc-mingw32 %s | llvm-readobj -s -sr -sd | FileCheck %s
 
+.section baz, "xr"
+	.def	X
+	.scl	2;
+	.type	32;
+	.endef
+	.globl	X
+X:
+	mov	Y-X+42,	%eax
+	retl
+
+	.def	Y
+	.scl	2;
+	.type	32;
+	.endef
+	.globl	Y
+Y:
+	retl
+
 	.def	 _foobar;
 	.scl	2;
 	.type	32;
@@ -30,3 +48,10 @@ _rust_crate:
 // CHECK:        SectionData (
 // CHECK-NEXT:     0000: 00000000 00000000 1C000000 20000000
 // CHECK-NEXT:   )
+
+// CHECK:        Name: baz
+// CHECK:        Relocations [
+// CHECK-NEXT:   ]
+// CHECK:        SectionData (
+// CHECK-NEXT:     0000: A1300000 00C3C3
+// CHECK-NEXT:   )