[Bug target/59289] New: [ARM] regression on unsigned-extend-2.c

[christophe.lyon at st dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59289

            Bug ID: 59289
           Summary: [ARM] regression on unsigned-extend-2.c
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: christophe.lyon at st dot com

Since commit 203160 (New rtx costs infrastructure for ARM), I have noticed that
gcc.target/arm/unsigned-extend-2.c scan-assembler ands
gcc.target/arm/unsigned-extend-2.c scan-assembler-not cmp
now FAIL (used to PASS).

I have configured GCC as:
target: arm-none-linux-gnueabihf
mode: thumb
cpu: cortex-a15
fpu: neon-vfpv4

With r203159:
    movs    r3, #8
.L3:
    lsrs    r0, r0, #1
    subs    r3, r3, #1
    ands    r3, r3, #255
    bne    .L3
    bx    lr

with r203160:
    movs    r3, #0
.L3:
    lsrs    r0, r0, #1
    adds    r3, r3, #1
    cmp    r3, #8
    bne    .L3
    bx    lr

It seems that code gen has slightly evolved in trunk since r203160, but the
test still fails.

The code sequence does not seem really worse than the original one, but the
testcase should at least be updated.