[Bug tree-optimization/77820] A jump threading opportunity with conditionals

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77820

--- Comment #3 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Author: law
Date: Thu Jun 13 18:55:55 2019
New Revision: 272261

URL: https://gcc.gnu.org/viewcvs?rev=272261&root=gcc&view=rev
Log:
        PR tree-optimization/77820
        * tree-ssa-threadedge.c
        (edge_forwards_cmp_to_conditional_jump_through_empty_bb_p): New
        function.
        (thread_across_edge): Add call to
        edge_forwards_cmp_to_conditional_jump_through_empty_bb_p.

        PR tree-optimization/77820
        * gcc.dg/tree-ssa/phi_on_compare-1.c: New testcase.
        * gcc.dg/tree-ssa/phi_on_compare-2.c: New testcase.
        * gcc.dg/tree-ssa/phi_on_compare-3.c: New testcase.
        * gcc.dg/tree-ssa/phi_on_compare-4.c: New testcase.
        * gcc.dg/tree-ssa/split-path-6.c: Update testcase.
        * gcc.target/sh/pr51244-20.c: Update testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-1.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-2.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-3.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-4.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c
    trunk/gcc/testsuite/gcc.target/sh/pr51244-20.c
    trunk/gcc/tree-ssa-threadedge.c