Object/COFF: Support large relocation table.
NumberOfRelocations field in COFF section table is only 16-bit wide. If an
object has more than 65535 relocations, the number of relocations is stored
to VirtualAddress field in the first relocation field, and a special flag
(IMAGE_SCN_LNK_NRELOC_OVFL) is set to Characteristics field.
In test we cheated a bit. I made up a test file so that it has
IMAGE_SCN_LNK_NRELOC_OVFL flag but the number of relocations is much smaller
than 65535. This is to avoid checking in a large test file just to test a
file with many relocations.
Differential Revision: http://llvm-reviews.chandlerc.com/D3139
llvm-svn: 204418
diff --git a/llvm/lib/Object/COFFObjectFile.cpp b/llvm/lib/Object/COFFObjectFile.cpp
index 8036ab1..5ad8f84 100644
--- a/llvm/lib/Object/COFFObjectFile.cpp
+++ b/llvm/lib/Object/COFFObjectFile.cpp
@@ -367,25 +367,46 @@
relocation_iterator COFFObjectFile::section_rel_begin(DataRefImpl Ref) const {
const coff_section *Sec = toSec(Ref);
DataRefImpl Ret;
- if (Sec->NumberOfRelocations == 0)
+ if (Sec->NumberOfRelocations == 0) {
Ret.p = 0;
- else
- Ret.p = reinterpret_cast<uintptr_t>(base() + Sec->PointerToRelocations);
-
+ } else {
+ auto begin = reinterpret_cast<const coff_relocation*>(
+ base() + Sec->PointerToRelocations);
+ if (Sec->hasExtendedRelocations()) {
+ // Skip the first relocation entry repurposed to store the number of
+ // relocations.
+ begin++;
+ }
+ Ret.p = reinterpret_cast<uintptr_t>(begin);
+ }
return relocation_iterator(RelocationRef(Ret, this));
}
+static uint32_t getNumberOfRelocations(const coff_section *Sec,
+ const uint8_t *base) {
+ // The field for the number of relocations in COFF section table is only
+ // 16-bit wide. If a section has more than 65535 relocations, 0xFFFF is set to
+ // NumberOfRelocations field, and the actual relocation count is stored in the
+ // VirtualAddress field in the first relocation entry.
+ if (Sec->hasExtendedRelocations()) {
+ auto *FirstReloc = reinterpret_cast<const coff_relocation*>(
+ base + Sec->PointerToRelocations);
+ return FirstReloc->VirtualAddress;
+ }
+ return Sec->NumberOfRelocations;
+}
+
relocation_iterator COFFObjectFile::section_rel_end(DataRefImpl Ref) const {
const coff_section *Sec = toSec(Ref);
DataRefImpl Ret;
- if (Sec->NumberOfRelocations == 0)
+ if (Sec->NumberOfRelocations == 0) {
Ret.p = 0;
- else
- Ret.p = reinterpret_cast<uintptr_t>(
- reinterpret_cast<const coff_relocation*>(
- base() + Sec->PointerToRelocations)
- + Sec->NumberOfRelocations);
-
+ } else {
+ auto begin = reinterpret_cast<const coff_relocation*>(
+ base() + Sec->PointerToRelocations);
+ uint32_t NumReloc = getNumberOfRelocations(Sec, base());
+ Ret.p = reinterpret_cast<uintptr_t>(begin + NumReloc);
+ }
return relocation_iterator(RelocationRef(Ret, this));
}