[ARM] Optimize compare against smin/umin

[Kyrill Tkachov]

Hi Michael,

On 26/07/15 23:54, Michael Collison wrote:
> Here is an updated patch that addresses the issues you mentioned:
>
> 2015-07-24  Michael Collison  <michael.collison@linaro.org
>                       Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
>
>                 * gcc/config/arm/arm.md (*arm_smin_cmp): New pattern.
>                 (*arm_umin_cmp): Likewise.
>                 * gcc.target/arm/mincmp.c: Test min compare idiom.

Just "New test." would be a better ChangeLog entry for this.

>
> diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
> index 0be70a8..361c292 100644
> --- a/gcc/config/arm/arm.md
> +++ b/gcc/config/arm/arm.md
> @@ -3455,6 +3455,44 @@
>       (set_attr "type" "multiple,multiple")]
>    )
>
> +;; t = (s/u)min (x, y)
> +;; cc = cmp (t, z)
> +;; is the same as
> +;; cmp x, z
> +;; cmpge(u) y, z
> +
> +(define_insn_and_split "*arm_smin_cmp"
> +  [(set (reg:CC CC_REGNUM)
> +    (compare:CC
> +     (smin:SI (match_operand:SI 0 "s_register_operand" "r")
> +          (match_operand:SI 1 "s_register_operand" "r"))
> +     (match_operand:SI 2 "s_register_operand" "r")))]
> +  "TARGET_32BIT"
> +  "#"
> +  "&& reload_completed"
> +  [(set (reg:CC CC_REGNUM)
> +    (compare:CC (match_dup 0) (match_dup 2)))
> +   (cond_exec (ge:CC (reg:CC CC_REGNUM) (const_int 0))
> +          (set (reg:CC CC_REGNUM)
> +           (compare:CC (match_dup 1) (match_dup 2))))]
> +)
> +
> +(define_insn_and_split "*arm_umin_cmp"
> +  [(set (reg:CC CC_REGNUM)
> +    (compare:CC
> +     (umin:SI (match_operand:SI 0 "s_register_operand" "r")
> +          (match_operand:SI 1 "s_register_operand" "r"))
> +     (match_operand:SI 2 "s_register_operand" "r")))]
> +  "TARGET_32BIT"
> +  "#"
> +  "&& reload_completed"
> +  [(set (reg:CC CC_REGNUM)
> +    (compare:CC (match_dup 0) (match_dup 2)))
> +   (cond_exec (geu:CC (reg:CC CC_REGNUM) (const_int 0))
> +          (set (reg:CC CC_REGNUM)
> +           (compare:CC (match_dup 1) (match_dup 2))))]
> +)
> +
>    (define_expand "umaxsi3"
>      [(parallel [
>        (set (match_operand:SI 0 "s_register_operand" "")
> diff --git a/gcc/testsuite/gcc.target/arm/mincmp.c
> b/gcc/testsuite/gcc.target/arm/mincmp.c
> new file mode 100644
> index 0000000..2a55c6d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/arm/mincmp.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +/* { dg-require-effective-target arm32 } */
> +
> +#define min(x, y) ((x) <= (y)) ? (x) : (y)
> +
> +unsigned int foo (unsigned int i, unsigned int x ,unsigned int y)

Comma after "unsigned int x" in the wrong place.

> +{
> +  return i < (min (x, y));
> +}
> +
> +int bar (int i, int x, int y)
> +{
> +  return i < (min (x, y));
> +}

Can you please use GNU style for the testcase.
New line after return type, function name an arguments on their own line.

Ok with these changes.

Thanks,
Kyrill