[Object][MachO] Rewrite macho-invalid-fat-arch-size into YAML

Summary:
Rewrite one of the invalid macho test input file with YAML file. The
original invalid macho is breaking our internal test infrastusture
because it is too broken to be copy around.

Need to relax an assertion in the YAML/MachoEmitter to allow yaml2obj to
write an invalid object like this.

rdar://problem/56879982

Reviewers: beanz, mtrent

Reviewed By: beanz

Subscribers: hiraditya, jkorous, dexonsmith, ributzka, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69856

Author: cachemeifyoucan

llvm/lib/ObjectYAML/MachOEmitter.cpp

@@ -494,7 +494,8 @@ void UniversalWriter::writeMachO(raw_ostream &OS) {
   writeFatArchs(OS);
 
   auto &FatFile = *ObjectFile.FatMachO;
-  assert(FatFile.FatArchs.size() == FatFile.Slices.size());
+  assert(FatFile.FatArchs.size() > FatFile.Slices.size() &&
+         "Cannot write Slices if not decribed in FatArches");
   for (size_t i = 0; i < FatFile.Slices.size(); i++) {
     ZeroToOffset(OS, FatFile.FatArchs[i].offset);
     MachOWriter Writer(FatFile.Slices[i]);

llvm/test/Object/Inputs/macho-invalid-fat-arch-size

@@ -0,0 +1,12 @@
+--- !fat-mach-o
+FatHeader:       
+  magic:           0xCAFEBABE
+  nfat_arch:       1
+FatArchs:        
+  - cputype:         0x00000007
+    cpusubtype:      0x00000003
+    offset:          0x000000000000020
+    size:            32
+    align:           2
+Slices:
+...

llvm/test/Object/Inputs/macho-invalid-fat-arch-size.yaml

@@ -491,8 +491,8 @@ INVALID-EXPORT-OVERLAP: macho-invalid-export-overlap': truncated or malformed ob
 RUN: not llvm-objdump --macho --universal-headers %p/Inputs/macho-invalid-fat-header 2>&1 | FileCheck -check-prefix INVALID-FAT-HEADER %s
 INVALID-FAT-HEADER: macho-invalid-fat-header': truncated or malformed fat file (contains zero architecture types)
 
-RUN: not llvm-objdump --macho --universal-headers %p/Inputs/macho-invalid-fat-arch-size 2>&1 | FileCheck -check-prefix INVALID-FAT-ARCH-SIZE %s
-INVALID-FAT-ARCH-SIZE: macho-invalid-fat-arch-size': truncated or malformed fat file (offset plus size of cputype (7) cpusubtype (3) extends past the end of the file)
+RUN: yaml2obj %p/Inputs/macho-invalid-fat-arch-size.yaml -o - | not llvm-objdump --macho --universal-headers - 2>&1 | FileCheck -check-prefix INVALID-FAT-ARCH-SIZE %s
+INVALID-FAT-ARCH-SIZE: '-': truncated or malformed fat file (offset plus size of cputype (7) cpusubtype (3) extends past the end of the file)
 
 RUN: not llvm-objdump --macho --universal-headers %p/Inputs/macho-invalid-fat-arch-bigalign 2>&1 | FileCheck -check-prefix INVALID-FAT-ARCH-BIGALIGN %s
 INVALID-FAT-ARCH-BIGALIGN: macho-invalid-fat-arch-bigalign': truncated or malformed fat file (align (2^212) too large for cputype (7) cpusubtype (3) (maximum 2^15))