[Bug target/43814] New: gcc failed to inline memcpy

[carrot at google dot com]

Attached is a simplified test case from dalvik VM. Compile it with options
-march=armv7-a -mthumb -Os -finline-functions, gcc generates

Dalvik_sun_misc_Unsafe_getObject:
        push    {r0, r1, r2, r4, r5, lr}
        ldr     r5, [r0, #4]
        mov     r4, r1
        movs    r2, #8
        add     r1, r0, #8
        mov     r0, sp
        bl      memcpy
        ldr     r3, [sp, #0]
        ldr     r3, [r5, r3]
        str     r3, [r4, #0]
        pop     {r1, r2, r3, r4, r5, pc}

If we inline memcpy, the result can be

        LDRD     r2,r0,[r0,#4]
        LDR      r0,[r2,r0]
        STR      r0,[r1,#0]
        BX       lr


There are at least 2 problems prevent it to be inlined for target arm.

1. In function emit_block_move_hints, for some unknown reason, the alignment is
wrongly computed as 8 bits.

2. The MOVE_RATIO defined in arm.h is too small.

#define MOVE_RATIO(speed) (arm_tune_xscale ? 4 : 2)

It means only when we move 1 unit of memory, then the memcpy can get a chance
to be inlined.


-- 
           Summary: gcc failed to inline memcpy
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: carrot at google dot com
 GCC build triplet: i686-linux
  GCC host triplet: i686-linux
GCC target triplet: arm-eabi


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43814