[Bug middle-end/37780] Conditional expression with __builtin_clz() should be optimized out

[ktkachov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37780

--- Comment #6 from ktkachov at gcc dot gnu.org ---
Author: ktkachov
Date: Mon Jun  6 16:06:05 2016
New Revision: 237141

URL: https://gcc.gnu.org/viewcvs?rev=237141&root=gcc&view=rev
Log:
[3/3][RTL ifcvt] PR middle-end/37780: Conditional expression with
__builtin_clz() should be optimized out

        PR middle-end/37780
        * ifcvt.c (noce_try_ifelse_collapse): New function.
        Declare prototype.
        (noce_process_if_block): Call noce_try_ifelse_collapse.
        * simplify-rtx.c (simplify_cond_clz_ctz): New function.
        (simplify_ternary_operation): Use the above to simplify
        conditional CLZ/CTZ expressions.

        * gcc.c-torture/execute/pr37780.c: New test.
        * gcc.target/aarch64/pr37780_1.c: Likewise.
        * gcc.target/arm/pr37780_1.c: Likewise.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr37780.c
    trunk/gcc/testsuite/gcc.target/aarch64/pr37780_1.c
    trunk/gcc/testsuite/gcc.target/arm/pr37780_1.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/ifcvt.c
    trunk/gcc/simplify-rtx.c
    trunk/gcc/testsuite/ChangeLog