diff mbox series

[v6,08/11] AArch64/SVE: Relax the expectations of the popcnt-sve test

Message ID 20251206165518.5449-9-chris.bazley@arm.com
State Deferred
Delegated to: Tamar Christina
Headers
Series Extend BB SLP vectorization to use predicated tails |

Commit Message

Christopher Bazley Dec. 6, 2025, 4:55 p.m. UTC 
  When predicated tails are enabled for basic block SLP vectorization,
the assembly language generated by GCC when compiling popcnt-sve.c
will change. Relax the regular expressions used by this test in
preparation.

Currently, analysis of f_v8hi succeeds with vector mode V16QI and the
following GIMPLE is produced:

vector(8) short unsigned intD.19 vect__1.18D.4648;
...
vect__1.18_69 = MEM <vector(8) short unsigned intD.19>
  [(short unsigned intD.19 *)vectp.17_68 clique 1 base 1];
vect_patt_60.19_70 = .POPCOUNT (vect__1.18_69);

With predicated tails, analysis instead succeeds with a variable-length
vector mode and the following GIMPLE is produced:

vector([8,8]) short unsigned intD.19 vect__1.18D.4649;
...
slp_mask_45 = .WHILE_ULT (0, 8, { 0, ... }); # VUSE <.MEM_25(D)>
vect__1.18_46 = .MASK_LOAD (vectp.17_44, 16B, slp_mask_45, { 0, ... });
vect_patt_36.19_47 = .POPCOUNT (vect__1.18_46);

When lowered to RTL, the WHILE_ULT is replaced by
reinterpretation of a V16QI as VNx8HI:

(insn 7 4 8 2 (
  set (reg:V16QI 107) (mem:V16QI (reg/v/f:DI 103 [ b ]) [1 S16 A16])
) "gcc.target/aarch64/popcnt-sve.c":33:8 discrim 1 -1 (nil))

(insn 8 7 9 2 (
  set (reg:VNx8HI 106) (subreg:VNx8HI (reg:V16QI 107) 0))
  "gcc.target/aarch64/popcnt-sve.c":33:8 discrim 1 -1 (nil))

A mask is still required to lower POPCOUNT, so an all-ones mask
is synthesized:

(insn 9 8 10 2 (set (reg:VNx16BI 108)
  (const_vector:VNx16BI repeat [(const_int 1 [0x1])
  ])) "gcc.target/aarch64/popcnt-sve.c":69:8 discrim 1 -1
(nil))

(insn 10 9 11 2 (set (reg:VNx4SI 105)
  (unspec:VNx4SI [
    (subreg:VNx4BI (reg:VNx16BI 108) 0)
    (popcount:VNx4SI (reg:VNx4SI 106))
  ] UNSPEC_PRED_X))
  "gcc.target/aarch64/popcnt-sve.c":69:8 discrim 1 -1
(nil))

However, this mask is not the same as the specific-width mask
currently expected by the tests.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/popcnt-sve.c: Update test expectations
	to allow both current and alternative valid mask
	specifications.

---
 gcc/testsuite/gcc.target/aarch64/popcnt-sve.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/gcc/testsuite/gcc.target/aarch64/popcnt-sve.c b/gcc/testsuite/gcc.target/aarch64/popcnt-sve.c
index c3b4c69b4b4..117a5ca8f1b 100644
--- a/gcc/testsuite/gcc.target/aarch64/popcnt-sve.c
+++ b/gcc/testsuite/gcc.target/aarch64/popcnt-sve.c
@@ -4,7 +4,7 @@ 
 
 /*
 ** f_v4hi:
-**	ptrue	(p[0-7]).b, vl8
+**	ptrue	(p[0-7]).b, (?:vl8|all)
 **	ldr	d([0-9]+), \[x0\]
 **	cnt	z\2.h, \1/m, z\2.h
 **	str	d\2, \[x1\]
@@ -21,7 +21,7 @@  f_v4hi (unsigned short *__restrict b, unsigned short *__restrict d)
 
 /*
 ** f_v8hi:
-**	ptrue	(p[0-7]).b, vl16
+**	ptrue	(p[0-7]).b, (?:vl16|all)
 **	ldr	q([0-9]+), \[x0\]
 **	cnt	z\2.h, \1/m, z\2.h
 **	str	q\2, \[x1\]
@@ -42,7 +42,7 @@  f_v8hi (unsigned short *__restrict b, unsigned short *__restrict d)
 
 /*
 ** f_v2si:
-**	ptrue	(p[0-7]).b, vl8
+**	ptrue	(p[0-7]).b, (?:vl8|all)
 **	ldr	d([0-9]+), \[x0\]
 **	cnt	z\2.s, \1/m, z\2.s
 **	str	d\2, \[x1\]
@@ -57,7 +57,7 @@  f_v2si (unsigned int *__restrict b, unsigned int *__restrict d)
 
 /*
 ** f_v4si:
-**	ptrue	(p[0-7]).b, vl16
+**	ptrue	(p[0-7]).b, (?:vl16|all)
 **	ldr	q([0-9]+), \[x0\]
 **	cnt	z\2.s, \1/m, z\2.s
 **	str	q\2, \[x1\]
@@ -74,7 +74,7 @@  f_v4si (unsigned int *__restrict b, unsigned int *__restrict d)
 
 /*
 ** f_v2di:
-**	ptrue	(p[0-7]).b, vl16
+**	ptrue	(p[0-7]).b, (?:vl16|all)
 **	ldr	q([0-9]+), \[x0\]
 **	cnt	z\2.d, \1/m, z\2.d
 **	str	q\2, \[x1\]