[Bug tree-optimization/58459] New: [4.9 regression] Loop invariant is not hoisted out of loop after r202525.

[ysrumyan at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58459

            Bug ID: 58459
           Summary: [4.9 regression] Loop invariant is not hoisted out of
                    loop after r202525.
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ysrumyan at gmail dot com

We noticed significant performance regression on important bench from eembc2.0
suite which can be exhibit with attached test-case.

Assembly produced compiler prior to r202525 for innermost loop:

.L18:
    movl    %esi, %ebp
    movl    8(%eax), %edx
    sall    %cl, %ebp
    movl    12(%eax), %eax
    testl    %ebp, %ebx  <-- p->key is hoisted out of loop
    cmove    %edx, %eax
    movl    %ecx, %edx

but assembly produced compiler after r202525 contains redundant load:

.L17:
    movl    %esi, %ebp
    movl    8(%eax), %edx
    sall    %cl, %ebp
    movl    12(%eax), %eax
    testl    %ebp, (%ebx)  <-- p->key is not hoisted out of loop
    cmove    %edx, %eax
    movl    %ecx, %edx

The test-case must be compiled with -Ofast -m32 -march=atom -mtune=atom
options.