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Re: [GCC][PATCH][Aarch64] Stop redundant zero-extension after UMOV when in DI mode
- From: Sudakshina Das <sudi dot das at arm dot com>
- To: Sam Tebbs <sam dot tebbs at arm dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Marcus Shawcroft <marcus dot shawcroft at arm dot com>
- Cc: nd <nd at arm dot com>, Richard Earnshaw <richard dot earnshaw at arm dot com>, James Greenhalgh <james dot greenhalgh at arm dot com>
- Date: Mon, 23 Jul 2018 17:01:20 +0100
- Subject: Re: [GCC][PATCH][Aarch64] Stop redundant zero-extension after UMOV when in DI mode
- References: <953dbdd2-e20c-4587-3e0d-ad1a65fc93c6@arm.com>
Hi Sam
On Monday 23 July 2018 11:39 AM, Sam Tebbs wrote:
Hi all,
This patch extends the aarch64_get_lane_zero_extendsi instruction
definition to
also cover DI mode. This prevents a redundant AND instruction from being
generated due to the pattern failing to be matched.
Example:
typedef char v16qi __attribute__ ((vector_size (16)));
unsigned long long
foo (v16qi a)
{
return a[0];
}
Previously generated:
foo:
umov w0, v0.b[0]
and x0, x0, 255
ret
And now generates:
foo:
umov w0, v0.b[0]
ret
Bootstrapped on aarch64-none-linux-gnu and tested on aarch64-none-elf
with no
regressions.
gcc/
2018-07-23 Sam Tebbs <sam.tebbs@arm.com>
* config/aarch64/aarch64-simd.md
(*aarch64_get_lane_zero_extendsi<mode>):
Rename to...
(*aarch64_get_lane_zero_extend<mode><VDQQH:mode>): ... This.
Use GPI iterator instead of SI mode.
gcc/testsuite
2018-07-23 Sam Tebbs <sam.tebbs@arm.com>
* gcc.target/aarch64/extract_zero_extend.c: New file
You will need an approval from a maintainer, but I would only add one
request to this:
diff --git a/gcc/config/aarch64/aarch64-simd.md
b/gcc/config/aarch64/aarch64-simd.md
index 89e38e6..15fb661 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -3032,15 +3032,16 @@
[(set_attr "type" "neon_to_gp<q>")]
)
-(define_insn "*aarch64_get_lane_zero_extendsi<mode>"
- [(set (match_operand:SI 0 "register_operand" "=r")
- (zero_extend:SI
+(define_insn "*aarch64_get_lane_zero_extend<mode><VDQQH:mode>"
+ [(set (match_operand:GPI 0 "register_operand" "=r")
+ (zero_extend:GPI
Since you are adding 4 new patterns with this change, could you add
more cases in your test as well to make sure you have coverage for each
of them.
Thanks
Sudi
(vec_select:<VEL>
(match_operand:VDQQH 1 "register_operand" "w")
(parallel [(match_operand:SI 2 "immediate_operand" "i")]))))]
"TARGET_SIMD"
{
- operands[2] = aarch64_endian_lane_rtx (<MODE>mode, INTVAL
(operands[2]));
+ operands[2] = aarch64_endian_lane_rtx (<VDQQH:MODE>mode,
+ INTVAL (operands[2]));
return "umov\\t%w0, %1.<Vetype>[%2]";
}
[(set_attr "type" "neon_to_gp<q>")]