[llvm] r253464 - Fix bug where WinCOFFObjectWriter would assume starting from an empty output.

[Manuel Klimek via llvm-commits]

Author: klimek
Date: Wed Nov 18 09:24:17 2015
New Revision: 253464

URL: http://llvm.org/viewvc/llvm-project?rev=253464&view=rev
Log:
Fix bug where WinCOFFObjectWriter would assume starting from an empty output.

Starting on an input stream that is not at offset 0 would trigger the
assert in WinCOFFObjectWriter.cpp:1065:

  assert(getStream().tell() <= (*i)->Header.PointerToRawData &&
               "Section::PointerToRawData is insane!");

Added:
    llvm/trunk/test/MC/COFF/stdin.s
Modified:
    llvm/trunk/include/llvm/MC/MCObjectWriter.h
    llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp

Modified: llvm/trunk/include/llvm/MC/MCObjectWriter.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCObjectWriter.h?rev=253464&r1=253463&r2=253464&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/MCObjectWriter.h (original)
+++ llvm/trunk/include/llvm/MC/MCObjectWriter.h Wed Nov 18 09:24:17 2015
@@ -49,6 +49,10 @@ protected: // Can only create subclasses
   MCObjectWriter(raw_pwrite_stream &OS, bool IsLittleEndian)
       : OS(&OS), IsLittleEndian(IsLittleEndian) {}
 
+  unsigned getInitialOffset() {
+    return OS->tell();
+  }
+
 public:
   virtual ~MCObjectWriter();
 

Modified: llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp?rev=253464&r1=253463&r2=253464&view=diff
==============================================================================
--- llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp (original)
+++ llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp Wed Nov 18 09:24:17 2015
@@ -962,7 +962,7 @@ void WinCOFFObjectWriter::writeObject(MC
 
   // Assign file offsets to COFF object file structures.
 
-  unsigned offset = 0;
+  unsigned offset = getInitialOffset();
 
   if (UseBigObj)
     offset += COFF::Header32Size;

Added: llvm/trunk/test/MC/COFF/stdin.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/COFF/stdin.s?rev=253464&view=auto
==============================================================================
--- llvm/trunk/test/MC/COFF/stdin.s (added)
+++ llvm/trunk/test/MC/COFF/stdin.s Wed Nov 18 09:24:17 2015
@@ -0,0 +1,3 @@
+// REQUIRES: shell
+// RUN: ( echo "test"; llvm-mc -filetype=obj -triple i686-pc-win32 %s ) > %t
+