[lld] e54cfa4 - [lld-macho] Fix bug in reading cpuSubType field.

[Vy Nguyen via llvm-commits]

Author: Vy Nguyen
Date: 2022-12-08T22:09:01-05:00
New Revision: e54cfa48d2d56e025fee9e239f8ba4fdec5520c8

URL: https://github.com/llvm/llvm-project/commit/e54cfa48d2d56e025fee9e239f8ba4fdec5520c8
DIFF: https://github.com/llvm/llvm-project/commit/e54cfa48d2d56e025fee9e239f8ba4fdec5520c8.diff

LOG: [lld-macho] Fix bug in reading cpuSubType field.

Differential Revision: https://reviews.llvm.org/D139572

Added: 
    

Modified: 
    lld/MachO/InputFiles.cpp
    lld/test/MachO/fat-arch.s

Removed: 
    


################################################################################
diff  --git a/lld/MachO/InputFiles.cpp b/lld/MachO/InputFiles.cpp
index 7fb5594aa97c..b7a8c91250de 100644
--- a/lld/MachO/InputFiles.cpp
+++ b/lld/MachO/InputFiles.cpp
@@ -231,8 +231,14 @@ std::optional<MemoryBufferRef> macho::readFile(StringRef path) {
       return std::nullopt;
     }
 
-    if (read32be(&arch[i].cputype) != static_cast<uint32_t>(target->cpuType) ||
-        read32be(&arch[i].cpusubtype) != target->cpuSubtype)
+    uint32_t cpuType = read32be(&arch[i].cputype);
+    uint32_t cpuSubtype =
+        read32be(&arch[i].cpusubtype) & ~MachO::CPU_SUBTYPE_MASK;
+
+    // FIXME: LD64 has a more complex fallback logic here.
+    // Consider implementing that as well?
+    if (cpuType != static_cast<uint32_t>(target->cpuType) ||
+        cpuSubtype != target->cpuSubtype)
       continue;
 
     uint32_t offset = read32be(&arch[i].offset);

diff  --git a/lld/test/MachO/fat-arch.s b/lld/test/MachO/fat-arch.s
index 33928b1049be..fd03248b2ee0 100644
--- a/lld/test/MachO/fat-arch.s
+++ b/lld/test/MachO/fat-arch.s
@@ -1,16 +1,30 @@
 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=i386-apple-darwin %s -o %t.i386.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %s -o %t.x86_64.o
+# RUN: llvm-mc -filetype=obj -triple=arm64-apple-macos11.0 %s -o %t.arm64.o
+
 # RUN: llvm-lipo %t.i386.o %t.x86_64.o -create -o %t.fat.o
 # RUN: %lld -o /dev/null %t.fat.o
-
 # RUN: llvm-lipo %t.i386.o -create -o %t.noarch.o
 # RUN: not %lld -o /dev/null %t.noarch.o 2>&1 | \
 # RUN:    FileCheck %s -DFILE=%t.noarch.o
 # CHECK: error: unable to find matching architecture in [[FILE]]
 
+## Validates that we read the cpu-subtype correctly from a fat exec.
+# RUN: %lld -o %t.x86_64.out %t.x86_64.o
+# RUN: %lld -arch arm64 -o %t.arm64.out %t.arm64.o
+# RUN: llvm-lipo %t.x86_64.out %t.arm64.out -create -o %t.fat.exec.out
+
+# RUN: llvm-otool -h %t.fat.exec.out | FileCheck %s --check-prefix=PRE-COND
+# PRE-COND:             magic cputype cpusubtype  caps    filetype ncmds sizeofcmds      flags
+# PRE-COND-NEXT:  0xfeedfacf 16777223          3  0x80           2    13        648 0x00200085
+
+# RUN: %lld %t.x86_64.o -bundle_loader %t.fat.exec.out -bundle -o %t.fat.bundle
+# RUN: llvm-otool -h %t.fat.bundle | FileCheck %s --check-prefix=POST-COND
+# POST-COND:            magic cputype cpusubtype  caps    filetype ncmds sizeofcmds      flags
+# POST-COND-NEXT:  0xfeedfacf 16777223          3  0x00           8    10        520 0x00000085
+
 .text
 .global _main
 _main:
-  mov $0, %eax
   ret