On Mon, Aug 4, 2014 at 2:28 PM, Zhenqiang Chen <zhenqiang.c...@arm.com> wrote:
> Hi,
>
> For some TARGET, like ARM THUMB1, the offset in load/store should be nature
> aligned. But in function get_address_cost, when computing max_offset, it
> only tries byte-aligned offsets:
>
> ((unsigned HOST_WIDE_INT) 1 << i) - 1
>
> which can not meet thumb_legitimate_offset_p check called from
> thumb1_legitimate_address_p for HImode and SImode.
>
> The patch adds additional try for aligned offset:
>
> ((unsigned HOST_WIDE_INT) 1 << i) - GET_MODE_SIZE (address_mode).
>
> Bootstrap and no make check regression on X86-64.
> No make check regression on qemu for Cortex-m0 and Cortex-m3.
> For Cortex-m0, no performance changes with coremark and dhrystone. Coremark
> code size is ~0.44 smaller. And eembcv2 code size is ~0.22 smaller. CSiBE
> code size is ~0.05% smaller.
>
> OK for trunk?
>
> Thanks!
> -Zhenqiang
>
> ChangeLog
> 2014-08-04 Zhenqiang Chen <zhenqiang.c...@arm.com>
>
> * tree-ssa-loop-ivopts.c (get_address_cost): Try aligned offset.
>
> testsuite/ChangeLog:
> 2014-08-04 Zhenqiang Chen <zhenqiang.c...@arm.com>
>
> * gcc.target/arm/get_address_cost_aligned_max_offset.c: New test.
>
> diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c
> index 3b4a6cd..562122a 100644
> --- a/gcc/tree-ssa-loop-ivopts.c
> +++ b/gcc/tree-ssa-loop-ivopts.c
> @@ -3308,6 +3308,18 @@ get_address_cost (bool symbol_present, bool
> var_present,
> XEXP (addr, 1) = gen_int_mode (off, address_mode);
> if (memory_address_addr_space_p (mem_mode, addr, as))
> break;
> + /* For some TARGET, like ARM THUMB1, the offset should be nature
> + aligned. Try an aligned offset if address_mode is not QImode.
> */
> + off = (address_mode == QImode)
> + ? 0
> + : ((unsigned HOST_WIDE_INT) 1 << i)
> + - GET_MODE_SIZE (address_mode);
> + if (off > 0)
> + {
> + XEXP (addr, 1) = gen_int_mode (off, address_mode);
> + if (memory_address_addr_space_p (mem_mode, addr, as))
> + break;
> + }
Hi, Why not just check "address_mode != QImode"? Set off to 0 then
check it seems unnecessary.
Thanks,
bin
> }
> if (i == -1)
> off = 0;
> diff --git
> a/gcc/testsuite/gcc.target/arm/get_address_cost_aligned_max_offset.c
> b/gcc/testsuite/gcc.target/arm/get_address_cost_aligned_max_offset.c
> new file mode 100644
> index 0000000..cc3e2f7
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/arm/get_address_cost_aligned_max_offset.c
> @@ -0,0 +1,28 @@
> +/* { dg-do compile } */
> +/* { dg-options "-mthumb -O2" } */
> +/* { dg-require-effective-target arm_thumb1_ok } */
> +
> +unsigned int
> +test (const short p16[6 * 64])
> +{
> + unsigned int i = 6;
> + unsigned int ret = 0;
> +
> + do
> + {
> + unsigned long long *p64 = (unsigned long long*) p16;
> + unsigned int *p32 = (unsigned int*) p16;
> + ret += ret;
> + if (p16[1] || p32[1])
> + ret++;
> + else if (p64[1] | p64[2] | p64[3])
> + ret++;
> + p16 += 64;
> + i--;
> + } while (i != 0);
> +
> + return ret;
> +}
> +
> +/* { dg-final { scan-assembler-not "#22" } } */
> +/* { dg-final { scan-assembler-not "#14" } } */
>
>
>
