------- Comment #2 from ramana at gcc dot gnu dot org 2009-06-12 12:54 -------
(In reply to comment #1)
> Created an attachment (id=17983)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17983&action=view) [edit]
> test case
>
Your attachment didn't have #include <stdint.h> - Please try and supply
pre-processed input which is self contained . Adding a -I from a build
directory can be rather painful . Thanks -
> The spilling is occurred around the first loop:
>
> push {r4, r5, r6, r7, lr}
> sub sp, sp, #12
> .loc 1 5 0
> str r2, [sp, #4] // A
> .loc 1 6 0
> add r6, r1, r2
> mov r4, r0
> .loc 1 8 0
> b .L2
> .L5:
> .loc 1 10 0
> mov r7, #0
> ldrsh r5, [r4, r7]
> .loc 1 12 0
> cmp r2, r5
> bge .L3
> .loc 1 14 0
> ldrb r7, [r1]
> strb r7, [r1, r2]
> .loc 1 15 0
> strh r2, [r4]
> .loc 1 16 0
> lsl r1, r2, #1
> sub r2, r5, r2
> strh r2, [r1, r4]
> .L6:
> .loc 1 5 0
> ldr r5, [sp, #4] // B
> lsl r4, r5, #1
> add r0, r0, r4
> b .L4
> .L3:
> .loc 1 19 0
> lsl r7, r5, #1
> mov ip, r7
> add r4, r4, ip
> .loc 1 20 0
> add r1, r1, r5
> .loc 1 21 0
> sub r2, r2, r5
> .L2:
> .loc 1 8 0
> cmp r2, #0
> bgt .L5
> b .L6
> .L4:
> .loc 1 30 0
> mov r1, #0
>
>
> The spilling is occurred at instruction A and reload at instruction B.
>
> The spilled value is x. The source code computes next_runs and next_alpha
> before while loop and preserve them through the loop body. But the generated
> code preserve next_alpha, original runs and original x through the loop body
> and compute next_runs after the loop. This caused an extra usage of register
> and results in a register spilling.
>
Could you say what you'd like the code to be because I don't see an option but
to spill one of the values here. ?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40416
