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Diffstat (limited to 'docs/HowToSubmitABug.html')
| -rw-r--r-- | docs/HowToSubmitABug.html | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/docs/HowToSubmitABug.html b/docs/HowToSubmitABug.html index 7c0b21766f..16e4c24a58 100644 --- a/docs/HowToSubmitABug.html +++ b/docs/HowToSubmitABug.html @@ -230,9 +230,15 @@ from producing invalid LLVM code (i.e., code not in SSA form, using values before defining them, etc.) which the verifier will check for after a pass finishes its run.</p> -<p>To debug a miscompilation, you should choose which program you wish to run -the output through, e.g. C backend, the JIT, or LLC, and a selection of passes, -one of which may be causing the error, and run, for example:</p> +<p>If it looks like the LLVM compiler is miscompiling a program, the very first +thing to check is to make sure it is not using undefined behavior. In +particular, check to see if the program valgrinds clean, passes purify, or some +other memory checker tool. Many of the "LLVM bugs" that we have chased down +ended up being bugs in the program being compiled, not LLVM.</p> + +<p>Once you determine that the program itself is not buggy, you should choose +which code generator you wish to compile the program with (e.g. C backend, the +JIT, or LLC) and optionally a series of LLVM passes to run. For example:</p> <div class="doc_code"> <p><tt><b>bugpoint</b> -run-cbe [... optimization passes ...] file-to-test.bc |