[Bug tree-optimization/39839] [4.3/4.4/4.5 regression] loop invariant motion causes stack spill

["steven at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #7 from steven at gcc dot gnu dot org  2010-01-02 00:49 -------
With "GCC: (GNU) 4.5.0 20090808 (experimental) [trunk revision 150579]" I get:

        .arch armv5te
        .fpu softvfp
        .eabi_attribute 20, 1
        .eabi_attribute 21, 1
        .eabi_attribute 23, 3
        .eabi_attribute 24, 1
        .eabi_attribute 25, 1
        .eabi_attribute 26, 1
        .eabi_attribute 30, 4
        .eabi_attribute 18, 4
        .code   16
        .file   "t.c"
        .text
        .align  1
        .global test
        .code   16
        .thumb_func
        .type   test, %function
test:
        push    {r3, r4, r5, r6, r7, lr}
        ldr     r3, .L7
        ldr     r5, .L7+4
.LPIC0:
        add     r3, pc
        add     r5, r3, r5
        mov     r7, r5
        mov     r4, r0
        ldr     r6, [r0]
        add     r7, r7, #8
        b       .L2
.L4:
        ldr     r1, [r4, #4]
        ldrb    r3, [r1]
        cmp     r3, #0
        bne     .L5
        mov     r3, r5
        b       .L3
.L5:
        add     r3, r5, #4
.L3:
        add     r1, r1, r6
        mov     r0, r7
        mov     r2, r6
        bl      func
        ldr     r3, [r4]
        sub     r3, r3, #1
        str     r3, [r4]
.L2:
        ldr     r3, [r4]
        cmp     r3, #0
        bge     .L4
        @ sp needed for prologue
        pop     {r3, r4, r5, r6, r7, pc}
.L8:
       .align  2
.L7:
        .word   _GLOBAL_OFFSET_TABLE_-(.LPIC0+4)
        .word   .LANCHOR0(GOTOFF)
        .size   test, .-test
        .section        .rodata
        .set    .LANCHOR0,. + 0
.LC0:
        .ascii  "xyz\000"
.LC1:
        .ascii  "pqr\000"
.LC2:
        .ascii  "abcde\000"
        .ident  "GCC: (GNU) 4.5.0 20090808 (experimental) [trunk revision
150579]"


I have no idea whether that is better or worse. Alexander, could you give this
a look please?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39839