[llvm-bugs] [Bug 42356] New: __builtin___clear_cache crashes the WebAssembly backend

via llvm-bugs llvm-bugs at lists.llvm.org
Fri Jun 21 10:53:43 PDT 2019


            Bug ID: 42356
           Summary: __builtin___clear_cache crashes the WebAssembly
           Product: libraries
           Version: trunk
          Hardware: All
                OS: All
            Status: NEW
          Severity: release blocker
          Priority: P
         Component: Backend: WebAssembly
          Assignee: unassignedbugs at nondot.org
          Reporter: gabravier at gmail.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 22129
  --> https://bugs.llvm.org/attachment.cgi?id=22129&action=edit
7z archive containing the attachments

This code crashes the WebAssembly backend with a SIGSEGV :

void f(char *begin, char *end)
    return __builtin___clear_cache((char *)begin, (char *)end);

Attached is a 7z file containing : 
- The source file that crashed clang
- the associated .bc file that clang emits with -emit-llvm
- the different stack traces for the following three invocations of llc :
$ llc crash.bc
$ llc crash.bc -relocation-model=pic
$ llc crash.bc -relocation-model=static
- the error message I got when using the recommended invocation of bugpoint
from https://llvm.org/docs/HowToSubmitABug.html#code-generator-bugs

I could not use bugpoint to pinpoint the crash more accurately, though I am
pretty sure that is directly related to __builtin___clear_cache. The stack
trace seems to implicate the assembly printer.

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