[lld] fb85578 - Fix PDB relocation on big-endian hosts
Ulrich Weigand via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 27 08:48:43 PDT 2023
Author: Ulrich Weigand
Date: 2023-04-27T17:48:27+02:00
New Revision: fb8557813afd41e09b4ba20091adf6b803967112
URL: https://github.com/llvm/llvm-project/commit/fb8557813afd41e09b4ba20091adf6b803967112
DIFF: https://github.com/llvm/llvm-project/commit/fb8557813afd41e09b4ba20091adf6b803967112.diff
LOG: Fix PDB relocation on big-endian hosts
When running the LLD test suite on a big-endian host, the
COFF/pdb-framedata.yaml test case currently fails.
As it turns out, this is because code in DebugSHandler::finish
intended to relocate RvaStart entries of FDO records does not
work correctly when compiled for a big-endian host.
Fixed by always reading file data in little-endian mode.
Reviewed By: aganea
Differential Revision: https://reviews.llvm.org/D149268
Added:
Modified:
lld/COFF/PDB.cpp
Removed:
################################################################################
diff --git a/lld/COFF/PDB.cpp b/lld/COFF/PDB.cpp
index 94af920d5e7a..8ca74ebc661e 100644
--- a/lld/COFF/PDB.cpp
+++ b/lld/COFF/PDB.cpp
@@ -950,7 +950,7 @@ void DebugSHandler::finish() {
// must also be rewritten to use the PDB string table.
for (const UnrelocatedFpoData &subsec : frameDataSubsecs) {
// Relocate the first four bytes of the subection and reinterpret them as a
- // 32 bit integer.
+ // 32 bit little-endian integer.
SectionChunk *debugChunk = subsec.debugChunk;
ArrayRef<uint8_t> subsecData = subsec.subsecData;
uint32_t relocIndex = subsec.relocIndex;
@@ -959,8 +959,9 @@ void DebugSHandler::finish() {
debugChunk->writeAndRelocateSubsection(debugChunk->getContents(),
unrelocatedRvaStart, relocIndex,
&relocatedRvaStart[0]);
- uint32_t rvaStart;
- memcpy(&rvaStart, &relocatedRvaStart[0], sizeof(uint32_t));
+ // Use of memcpy here avoids violating type-based aliasing rules.
+ support::ulittle32_t rvaStart;
+ memcpy(&rvaStart, &relocatedRvaStart[0], sizeof(support::ulittle32_t));
// Copy each frame data record, add in rvaStart, translate string table
// indices, and add the record to the PDB.
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