[lld] r216636 - [PECOFF] Implement Win64 base relocations

[Rui Ueyama]

Author: ruiu
Date: Wed Aug 27 19:47:11 2014
New Revision: 216636

URL: http://llvm.org/viewvc/llvm-project?rev=216636&view=rev
Log:
[PECOFF] Implement Win64 base relocations

Image Base field in the PE/COFF header is used as hint for the loader.
If the loader can load the executable at the specified address, that's
fine, but if not, it has to load it at a different address.

If that happens, the loader has to fix up the addresses in the
executable by adding the offset. The list of addresses that need to
be fixed is in .reloc section.

This patch is to emit x64 .reloc section contents.

Modified:
    lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
    lld/trunk/test/pecoff/reloc64.test

Modified: lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp?rev=216636&r1=216635&r2=216636&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp (original)
+++ lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp Wed Aug 27 19:47:11 2014
@@ -249,6 +249,7 @@ private:
       StringRef name, const std::vector<const DefinedAtom *> &atoms) const;
 
   mutable llvm::BumpPtrAllocator _alloc;
+  bool is64;
 };
 
 /// A DataDirectoryChunk represents data directory entries that follows the PE
@@ -446,7 +447,7 @@ AtomChunk::AtomChunk(const PECOFFLinking
                      const std::vector<const DefinedAtom *> &atoms)
     : SectionChunk(kindAtomChunk, sectionName,
                    computeCharacteristics(ctx, sectionName, atoms)),
-      _virtualAddress(0) {
+      _virtualAddress(0), is64(ctx.is64Bit()) {
   for (auto *a : atoms)
     appendAtom(a);
 }
@@ -633,11 +634,13 @@ void AtomChunk::addBaseRelocations(std::
   // should output debug messages with atom names and addresses so that we
   // can inspect relocations, and fix the tests (base-reloc.test, maybe
   // others) to use those messages.
+  int relType = is64 ? llvm::COFF::IMAGE_REL_AMD64_ADDR64
+                     : llvm::COFF::IMAGE_REL_I386_DIR32;
   for (const auto *layout : _atomLayouts) {
     const DefinedAtom *atom = cast<DefinedAtom>(layout->_atom);
     for (const Reference *ref : *atom)
       if ((ref->kindNamespace() == Reference::KindNamespace::COFF) &&
-          (ref->kindValue() == llvm::COFF::IMAGE_REL_I386_DIR32))
+          (ref->kindValue() == relType))
         relocSites.push_back(layout->_virtualAddr + ref->offsetInAtom());
   }
 }
@@ -822,10 +825,11 @@ std::vector<uint8_t> BaseRelocChunk::cre
   ptr += sizeof(ulittle32_t);
 
   // The rest of the block consists of offsets in the page.
+  uint16_t type = _ctx.is64Bit() ? llvm::COFF::IMAGE_REL_BASED_DIR64
+                                 : llvm::COFF::IMAGE_REL_BASED_HIGHLOW;
   for (uint16_t offset : offsets) {
     assert(offset < _ctx.getPageSize());
-    uint16_t val = (llvm::COFF::IMAGE_REL_BASED_HIGHLOW << 12) | offset;
-    *reinterpret_cast<ulittle16_t *>(ptr) = val;
+    *reinterpret_cast<ulittle16_t *>(ptr) = (type << 12) | offset;
     ptr += sizeof(ulittle16_t);
   }
   return contents;

Modified: lld/trunk/test/pecoff/reloc64.test
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/pecoff/reloc64.test?rev=216636&r1=216635&r2=216636&view=diff
==============================================================================
--- lld/trunk/test/pecoff/reloc64.test (original)
+++ lld/trunk/test/pecoff/reloc64.test Wed Aug 27 19:47:11 2014
@@ -3,9 +3,13 @@
 
 # RUN: lld -flavor link /out:%t.exe /subsystem:console /machine:x64 \
 # RUN:   /entry:fn1 -- %t1.obj %t2.obj
-# RUN: llvm-objdump -d %t.exe | FileCheck %s
+# RUN: llvm-objdump -d %t.exe | FileCheck -check-prefix=TEXT %s
+# RUN: llvm-objdump -s %t.exe | FileCheck -check-prefix=RELOC %s
 
-CHECK:      Disassembly of section .text:
-CHECK-NEXT: .text:
-CHECK-NEXT:   1000:  e8 0b 00 00 00   callq 11
-CHECK-NEXT:   1005:  48 b8 10 10 00 40 01 00 00 00 movabsq $5368713232, %rax
+TEXT:      Disassembly of section .text:
+TEXT-NEXT: .text:
+TEXT-NEXT:   1000:  e8 0b 00 00 00   callq 11
+TEXT-NEXT:   1005:  48 b8 10 10 00 40 01 00 00 00 movabsq $5368713232, %rax
+
+RELOC:      Contents of section .reloc:
+RELOC-NEXT: 2000 00100000 0c000000 07a00000 00000000  ................