[lld] r192930 - Fill gap in .text with NOP.

[Rui Ueyama]

Author: ruiu
Date: Thu Oct 17 17:45:16 2013
New Revision: 192930

URL: http://llvm.org/viewvc/llvm-project?rev=192930&view=rev
Log:
Fill gap in .text with NOP.

Modified:
    lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp

Modified: lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp?rev=192930&r1=192929&r2=192930&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp (original)
+++ lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp Thu Oct 17 17:45:16 2013
@@ -585,6 +585,20 @@ void SectionHeaderTableChunk::write(uint
 // \brief A TextSectionChunk represents a .text section.
 class TextSectionChunk : public SectionChunk {
 public:
+  virtual void write(uint8_t *fileBuffer) {
+    if (_atomLayouts.empty())
+      return;
+    // Fill the section with NOP (0x90) rather than NUL, so that the
+    // disassembler will not interpret a garbage between atoms as the beginning
+    // of multi-byte machine code. This does not change the behavior of
+    // resulting binary but help debugging.
+    uint8_t *start = fileBuffer + _atomLayouts.front()->_fileOffset;
+    uint8_t *end = fileBuffer + _atomLayouts.back()->_fileOffset;
+    memset(start, 0x90, end - start);
+
+    SectionChunk::write(fileBuffer);
+  }
+
   TextSectionChunk(const File &linkedFile)
       : SectionChunk(".text", characteristics) {
     buildContents(linkedFile, [](const DefinedAtom *atom) {