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[PATCH] fold a * (a > 0 ? 1 : -1) to abs(a) and related optimizations


Hi,
  I saw this on llvm's review site (https://reviews.llvm.org/D34579)
and I thought why not add it to GCC.  I expanded more than what was
done on the LLVM patch.

I added the following optimizations:
Transform X * (X > 0 ? 1 : -1) into ABS(X).
Transform X * (X >= 0 ? 1 : -1) into ABS(X).
Transform X * (X > 0.0 ? 1.0 : -1.0) into ABS(X).
Transform X * (X >= 0.0 ? 1.0 : -1.0) into ABS(X).
Transform X * (X > 0 ? -1 : 1) into -ABS(X).
Transform X * (X >= 0 ? -1 : 1) into -ABS(X).
Transform X * (X > 0.0 ? -1.0 : 1.0) into -ABS(X).
Transform X * (X >= 0.0 ? -1.0 : 1.0) into -ABS(X).
Transform X * (X < 0 ? 1 : -1) into -ABS(X).
Transform X * (X <= 0 ? 1 : -1) into -ABS(X).
Transform X * (X < 0.0 ? 1.0 : -1.0) into -ABS(X).
Transform X * (X <= 0.0 ? 1.0 : -1.0) into -ABS(X).
Transform X * (X < 0 ? -1 : 1) into ABS(X).
Transform X * (X <= 0 ? -1 : 1) into ABS(X).
Transform X * (X < 0.0 ? -1.0 : 1.0) into ABS(X).
Transform X * (X <= 0.0 ? -1.0 : 1.0) into ABS(X).

The floating points ones only happen when not honoring SNANS and not
honoring signed zeros.

OK?  Bootstrapped and tested on aarch64-linux-gnu with no regressions.

Thanks,
Andrew Pinski

ChangeLog:
* match.pd ( X * (X >/>=/</<= 0 ? 1 : -1)): New patterns.

Testsuite/ChangeLog:
* testsuite/gcc.dg/tree-ssa/mult-abs-1.c: New testcase.
* testsuite/gcc.dg/tree-ssa/mult-abs-2.c: New testcase.


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