[PATCH] D73531: [llvm-objdump] avoid crash disassembling unknown instruction

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer updated this revision to Diff 241654.
SjoerdMeijer added a comment.

Thanks for checking, and I have reduced the test case further:

- removed 2 instructions, and it indeed crashes on this very first byte `cb`. This triggers the assert listed in the description.
- I have also removed the mve target attribute from the command line, which is not necessary.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D73531/new/

https://reviews.llvm.org/D73531

Files:
  llvm/test/tools/llvm-objdump/ARM/unknown-instr.test
  llvm/tools/llvm-objdump/llvm-objdump.cpp


Index: llvm/tools/llvm-objdump/llvm-objdump.cpp
===================================================================
--- llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -1431,6 +1431,14 @@
         outs() << CommentStream.str();
         Comments.clear();
 
+        // If disassembly has failed, continue with the next instruction, to
+        // avoid analysing invalid/incomplete instruction information.
+        if (!Disassembled) {
+          outs() << "\n";
+          Index += Size;
+          continue;
+        }
+
         // Try to resolve the target of a call, tail call, etc. to a specific
         // symbol.
         if (MIA && (MIA->isCall(Inst) || MIA->isUnconditionalBranch(Inst) ||
Index: llvm/test/tools/llvm-objdump/ARM/unknown-instr.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-objdump/ARM/unknown-instr.test
@@ -0,0 +1,17 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objdump -D -triple=thumbv8.1m.main-none-eabi %t | FileCheck %s
+
+# CHECK:        00000000 .text:
+# CHECK-NEXT:       0: cb              <unknown>
+# CHECK-NEXT:       1: f3 f7 8b be     b.w #-49898
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS32
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_ARM
+Sections:
+  - Name:    .text
+    Type:    SHT_PROGBITS
+    Content: "cbf3f78bbe"


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