[PATCH] D11212: [SCEV] Apply NSW and NUW flags via poison value analysis

Bjarke Hammersholt Roune broune at google.com
Mon Jul 20 18:27:10 PDT 2015

broune added a comment.

In http://reviews.llvm.org/D11212#208037, @sanjoy wrote: [...]

> Side comment and optional: have you bootstrapped clang with this change?  That's a good sanity check for this sort of change.  You may consider bootstrapping with ubsan / asan too to get some extra coverage:  the extra control flow the sanitizers add tends to shake out a lot of bugs.

I'm not sure what this entails, but I made a guess: I took a release-with-asserts build of llvm, built with my patch, and used the binaries from that with cmake like so:

CXX=path/to/release/with/asserts/clang/bin/clang++ CC=path/to/release/with/asserts/clang/bin/clang++ cmake -G Ninja ../llvm -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=Yes

then I did ninja check and ninja check-asan. If that's not what you had in mind, feel free to let me know. I didn't find a guide on how to test LLVM via bootstrapping.

Comment at: lib/Analysis/ScalarEvolution.cpp:4207
@@ +4206,3 @@
+      // Do an operation by itself if a no-wrap flag can be applied, since the
+      // flag only applies to that particular operation.
sanjoy wrote:
> The `Do an operation by itself if a no-wrap flag can be applied` bit did not parse for me.
I clarified the comment.


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