[llvm-objdump][macho] Fix relative method list dumping for little endian hosts #85778
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alx32
referenced
this pull request
Mar 19, 2024
) For Mach-O, ld64 supports the -fobjc-relative-method-lists flag which changes the format in which method lists are generated. The format uses delta encoding vs the original direct-pointer encoding. This change adds support to llvm-objdump and llvm-otool for decoding/dumping of method lists in the delta format. Previously, if a binary with this information format was passed to the tooling, it would output invalid information, trying to parse the delta lists as pointer lists. After this change, the tooling will output correct information if a binary in this format is encountered. The output format is closest feasible match to XCode 15.1's otool output. Tests are included for both 32bit and 64bit binaries. The code style was matched as close as possible to existing implementation of parsing non-delta method lists. Diff between llvm-objdump and XCode 15.1 otool:  Note: This is a retry of this PR: #84250 On the original PR, the armv7+armv8 builds were failing due to absolute offsets being different. Co-authored-by: Alex B <[email protected]>
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@llvm/pr-subscribers-llvm-binary-utilities Author: None (alx32) Changes
This seems like the obvious fix. Full diff: https://github.com/llvm/llvm-project/pull/85778.diff 2 Files Affected:
diff --git a/llvm/test/tools/llvm-objdump/MachO/AArch64/macho-relative-method-lists.test b/llvm/test/tools/llvm-objdump/MachO/AArch64/macho-relative-method-lists.test
index 8e1a9b67970416..b1b96a41a32939 100644
--- a/llvm/test/tools/llvm-objdump/MachO/AArch64/macho-relative-method-lists.test
+++ b/llvm/test/tools/llvm-objdump/MachO/AArch64/macho-relative-method-lists.test
@@ -1,4 +1,3 @@
-XFAIL: system-aix
RUN: llvm-objdump --macho --objc-meta-data %p/Inputs/rel-method-lists-arm64_32.dylib | FileCheck %s --check-prefix=CHK32
RUN: llvm-otool -ov %p/Inputs/rel-method-lists-arm64_32.dylib | FileCheck %s --check-prefix=CHK32
diff --git a/llvm/tools/llvm-objdump/MachODump.cpp b/llvm/tools/llvm-objdump/MachODump.cpp
index 1b0e5ba279d06b..5e0d69a68d69b4 100644
--- a/llvm/tools/llvm-objdump/MachODump.cpp
+++ b/llvm/tools/llvm-objdump/MachODump.cpp
@@ -4499,11 +4499,15 @@ static void print_relative_method_list(uint32_t structSizeAndFlags,
outs() << indent << " (nameRefPtr extends past the end of the section)";
else {
if (pointerSize == 64) {
- name = get_pointer_64(*reinterpret_cast<const uint64_t *>(nameRefPtr),
- xoffset, left, xS, info);
+ uint64_t nameOff_64 = *reinterpret_cast<const uint64_t *>(nameRefPtr);
+ if (info->O->isLittleEndian() != sys::IsLittleEndianHost)
+ sys::swapByteOrder(nameOff_64);
+ name = get_pointer_64(nameOff_64, xoffset, left, xS, info);
} else {
- name = get_pointer_32(*reinterpret_cast<const uint32_t *>(nameRefPtr),
- xoffset, left, xS, info);
+ uint32_t nameOff_32 = *reinterpret_cast<const uint32_t *>(nameRefPtr);
+ if (info->O->isLittleEndian() != sys::IsLittleEndianHost)
+ sys::swapByteOrder(nameOff_32);
+ name = get_pointer_32(nameOff_32, xoffset, left, xS, info);
}
if (name != nullptr)
outs() << format(" %.*s", left, name);
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I'm seeing the same bug on s390x-linux, which is another big-endian platform like AIX. This PR does fix the problem for me, so it looks like a good fix to me. |
chencha3
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to chencha3/llvm-project
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Mar 23, 2024
…ian hosts (llvm#85778) `macho-relative-method-lists.test` is failing on little endian platforms, when matching 'name'. ``` CHK32-NEXT: name 0x144 (0x{{[0-9a-f]*}}) instance_method_00 next:10'0 X error: no match found 18: name 0x144 (0x7ac) ``` This seems like the obvious fix. Co-authored-by: Alex B <[email protected]>
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macho-relative-method-lists.testis failing on little endian platforms, when matching 'name'.This seems like the obvious fix.