How to use bugpoint reduce a IR test case?

(1) Find the temp files created by clang in the crash report. Usually, it is at the end of the crash report, which
points to a file in the /tmp/ directory. for example:
clang-5.0: note: diagnostic msg: /tmp/tsan_mutexset-bb0974.cpp
clang-5.0: note: diagnostic msg: /tmp/tsan_mutexset-bb0974.sh

(2) add '-S -emit-llvm -o tony.ll' to the script (tsan_mutexset-bb0974.sh in this example) to produce an .ll file.

(3) Then you write a simple script like this:
```#!/bin/bash
<broken-llc> $1 2>&1 | grep "<text of the assertion>" > /dev/null
if [[ $? -eq 0 ]]
then
  exit 1
else
  exit 0
fi

examples:
    $ cat reduceScript.sh
    ```#!/bin/bash
    /home/jtony/llvm/build/memcpyBootstrapSeanPatch/bin/llc $1 2>&1 | grep "Node emitted out of order - late" > /dev/null
    if [[ $? -eq 0 ]]
    then
       exit 1
    else
       exit 0
    fi
       
        jyj14ibm


(4)run the following to reduce the given *.ll file once you have both the IR file (tony.ll) and the script (reduceScript.sh):
`$ bugpoint -compile-custom -compile-command=reduceScript.sh tony.ll`

(5) Use llvm-dis to generate the eventual reduced IR (*.ll) file from the bitcode file (*.bc).
For example:
 llvm-dis bugpoint-reduced-simplified.bc

Feel free to update this initial bugpoint document.