[PATCH] [Instcombine] Recognize test for overflow in integer multiplication.

[Erik Verbruggen]

  I also did a patch for PR4917, but yours looks more complete. I have some different tests, and I'll see how they compare against this. Will probably do that tomorrow (CEST).

  Nitpick: I applied this patch on top of r205314, and I get the following warning:

  /Users/erik/dev/clang-llvm/llvm-git/lib/Transforms/InstCombine/InstCombineCompares.cpp:2204:9: warning: ignoring return value of function declared with
        warn_unused_result attribute [-Wunused-result]
          Mask.trunc(MulWidth);
          ^~~~~~~~~~ ~~~~~~~~

http://llvm-reviews.chandlerc.com/D2814