[PATCH GCC][1/4]Simplify (convert1 (minmax ((convert2 (x) c)))) into minmax (x c)
Richard Biener
richard.guenther@gmail.com
Tue Oct 25 11:48:00 GMT 2016
On Tue, Oct 25, 2016 at 1:21 PM, Bin Cheng <Bin.Cheng@arm.com> wrote:
> Hi,
> This is a patch set adding various match.pd patterns in order to generate simplified MIN/MAX_EXPR mostly from COND_EXPR. This is the first one optimizing (convert1 (minmax ((convert2 (x) c)))) to minmax (x c), if convert2 promotes x and convert1 demotes back to x's type. With this patch, generated assembly for test:
> .L4:
> ldr q0, [x3, x1]
> add w2, w2, 1
> cmp w0, w2
> ushll v2.4s, v0.4h, 0
> ushll2 v1.4s, v0.8h, 0
> umin v2.4s, v2.4s, v3.4s
> umin v1.4s, v1.4s, v3.4s
> xtn v4.4h, v2.4s
> xtn2 v4.8h, v1.4s
> str q4, [x3, x1]
> add x1, x1, 16
> bhi .L4
>
> can be improved to:
> .L4:
> ldr q0, [x3, x1]
> add w2, w2, 1
> cmp w0, w2
> umin v1.8h, v0.8h, v2.8h
> str q1, [x3, x1]
> add x1, x1, 16
> bhi .L4
>
> Bootstrap and test on x86_64 and AArch64 for whole patch set. Is it OK?
Why restrict to GIMPLE?
+/* (convert1 (minmax ((convert2 (x) c)))) -> minmax (x c) if convert2
+ promotes x and convert1 demotes back to x's type. */
+
+(for minmax (min max)
+ (simplify
+ (convert (minmax@0 (convert @1) INTEGER_CST@2))
+ (if (types_compatible_p (TREE_TYPE (@1), type))
comment mentions convert1 and convert2, just convert is correct I think.
Please use types_match instead of types_compatible_p, this is a
wrapper that does the correct thing for both GENERIC and GIMPLE.
+ (with
+ {
+ tree minmax_type = TREE_TYPE (@0);
+ signop sgn = TYPE_SIGN (type);
+ widest_int type_min = widest_int::from (wi::min_value (type), sgn);
+ widest_int type_max = widest_int::from (wi::max_value (type), sgn);
+ }
+ (if (sgn == TYPE_SIGN (minmax_type)
+ && TYPE_PRECISION (minmax_type) >= TYPE_PRECISION (type)
+ && wi::to_widest (@2) >= type_min && wi::to_widest (@2) <= type_max)
instead of this you can use int_fits_type_p (type, @2)
+ (minmax @1 { fold_convert (type, @2); }))))))
use
(minmax @1 (convert @2))
I believe the transform is also a win if @2 is not a constant but similarly
promoted as @1. This slightly complicates the patter and thus can
be done as followup (if we think it's useful at this point).
With the simplification you should get rid of the with{}
Thanks,
Richard.
> Thanks,
> bin
>
> 2016-10-21 Bin Cheng <bin.cheng@arm.com>
>
> * match.pd ((convert1 (minmax ((convert2 (x) c)))) -> minmax (x c)):
> New pattern.
>
> gcc/testsuite/ChangeLog
> 2016-10-21 Bin Cheng <bin.cheng@arm.com>
>
> * gcc.dg/fold-convmaxconv-1.c: New test.
> * gcc.dg/fold-convminconv-1.c: New test.
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