Hi all,
this patch is meant not to generate predication in loop when the
loop is operating only on full vectors.
Ex:
#+BEGIN_SRC C
/* Vector length is 256. */
void
f (int *restrict x, int *restrict y, unsigned int n) {
for (unsigned int i = 0; i < n * 8; ++i)
x[i] += y[i];
}
#+END_SRC
Compiling on aarch64 with -O3 -msve-vector-bits=256 current trunk
gives:
#+BEGIN_SRC asm
f:
.LFB0:
.cfi_startproc
lsl w2, w2, 3
cbz w2, .L1
mov x3, 0
whilelo p0.s, xzr, x2
.p2align 3,,7
.L3:
ld1w z0.s, p0/z, [x0, x3, lsl 2]
ld1w z1.s, p0/z, [x1, x3, lsl 2]
add z0.s, z0.s, z1.s
st1w z0.s, p0, [x0, x3, lsl 2]
add x3, x3, 8
whilelo p0.s, x3, x2
b.any .L3
.L1:
ret
.cfi_endproc
#+END_SRC
With the patch applied:
#+BEGIN_SRC asm
f:
.LFB0:
.cfi_startproc
lsl w3, w2, 3
cbz w3, .L1
mov x2, 0
ptrue p0.b, vl32
.p2align 3,,7
.L3:
ld1w z0.s, p0/z, [x0, x2, lsl 2]
ld1w z1.s, p0/z, [x1, x2, lsl 2]
add z0.s, z0.s, z1.s
st1w z0.s, p0, [x0, x2, lsl 2]
add x2, x2, 8
cmp x2, x3
bne .L3
.L1:
ret
.cfi_endproc
#+END_SRC
To achieve this we check earlier if the loop needs peeling and if is
not the case we do not set LOOP_VINFO_USING_PARTIAL_VECTORS_P to true.
I moved some logic from 'determine_peel_for_niter' to
'vect_need_peeling_or_part_vects_p' so it can be used for this purpose.
Bootstrapped and regtested on aarch64-linux-gnu.
Feedback is welcome, thanks.
Andrea
>From fdcceaa420d6c3b03cf22ab50e0f9c393e8e3932 Mon Sep 17 00:00:00 2001
From: Andrea Corallo <andrea.cora...@arm.com>
Date: Fri, 28 Aug 2020 16:01:15 +0100
Subject: [PATCH] vec: don't select partial vectors when unnecessary
gcc/ChangeLog
2020-09-09 Andrea Corallo <andrea.cora...@arm.com>
* tree-vect-loop.c (vect_need_peeling_or_part_vects_p): New function.
(determine_peel_for_niter): Move out some logic into
'vect_need_peeling_or_part_vects_p'.
gcc/testsuite/ChangeLog
2020-09-09 Andrea Corallo <andrea.cora...@arm.com>
* gcc.target/aarch64/sve/cost_model_10.c: New test.
* gcc.target/aarch64/sve/clastb_8.c: Update test for new
vectorization strategy.
* gcc.target/aarch64/sve/cost_model_5.c: Likewise.
* gcc.target/aarch64/sve/struct_vect_14.c: Likewise.
* gcc.target/aarch64/sve/struct_vect_15.c: Likewise.
* gcc.target/aarch64/sve/struct_vect_16.c: Likewise.
* gcc.target/aarch64/sve/struct_vect_17.c: Likewise.
---
.../gcc.target/aarch64/sve/clastb_8.c | 5 +-
.../gcc.target/aarch64/sve/cost_model_10.c | 12 +++
.../gcc.target/aarch64/sve/cost_model_5.c | 4 +-
.../gcc.target/aarch64/sve/struct_vect_14.c | 8 +-
.../gcc.target/aarch64/sve/struct_vect_15.c | 8 +-
.../gcc.target/aarch64/sve/struct_vect_16.c | 8 +-
.../gcc.target/aarch64/sve/struct_vect_17.c | 8 +-
gcc/tree-vect-loop.c | 86 +++++++++++--------
8 files changed, 81 insertions(+), 58 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/aarch64/sve/cost_model_10.c
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/clastb_8.c
b/gcc/testsuite/gcc.target/aarch64/sve/clastb_8.c
index 57c42082449..e61ff4ac92d 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/clastb_8.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/clastb_8.c
@@ -23,7 +23,4 @@ TEST_TYPE (uint64_t);
/* { dg-final { scan-assembler {\tclastb\t(h[0-9]+), p[0-7], \1, z[0-9]+\.h\n}
} } */
/* { dg-final { scan-assembler {\tclastb\t(s[0-9]+), p[0-7], \1, z[0-9]+\.s\n}
} } */
/* { dg-final { scan-assembler {\tclastb\t(d[0-9]+), p[0-7], \1, z[0-9]+\.d\n}
} } */
-/* { dg-final { scan-assembler {\twhilelo\tp[0-9]+\.b,} } } */
-/* { dg-final { scan-assembler {\twhilelo\tp[0-9]+\.h,} } } */
-/* { dg-final { scan-assembler {\twhilelo\tp[0-9]+\.s,} } } */
-/* { dg-final { scan-assembler {\twhilelo\tp[0-9]+\.d,} } } */
+/* { dg-final { scan-assembler {\tptrue\tp[0-9]+\.b,} 4 } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/cost_model_10.c
b/gcc/testsuite/gcc.target/aarch64/sve/cost_model_10.c
new file mode 100644
index 00000000000..bfac09ed1c1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/cost_model_10.c
@@ -0,0 +1,12 @@
+/* { dg-options "-O3 -msve-vector-bits=256" } */
+
+void
+f (int *restrict x, int *restrict y, unsigned int n)
+{
+ for (unsigned int i = 0; i < n * 8; ++i)
+ x[i] += y[i];
+}
+
+/* { dg-final { scan-assembler-not {\twhilelo\t} } } */
+/* { dg-final { scan-assembler {\tptrue\tp} } } */
+/* { dg-final { scan-assembler {\tcmp\tx[0-9]+, x[0-9]+\n} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/cost_model_5.c
b/gcc/testsuite/gcc.target/aarch64/sve/cost_model_5.c
index 250ca837324..f3a29fc38a1 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/cost_model_5.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/cost_model_5.c
@@ -9,5 +9,5 @@ vset (int *restrict dst, int *restrict src, int count)
*dst++ = 1;
}
-/* { dg-final { scan-assembler-not {\tst1w\tz} } } */
-/* { dg-final { scan-assembler-times {\tstp\tq} 2 } } */
+/* { dg-final { scan-assembler-times {\tst1w\tz} 2 } } */
+/* { dg-final { scan-assembler-not {\tstp\tq} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_14.c
b/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_14.c
index a16a79e51c0..45644b67bda 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_14.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_14.c
@@ -43,12 +43,12 @@
#undef NAME
#undef TYPE
-/* { dg-final { scan-assembler-times {\tld2b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tld2b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tld3b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tld4b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+, x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tst2b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tld4b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tst2b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tst3b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tst4b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tst4b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tld2h\t{z[0-9]+.h - z[0-9]+.h},
p[0-7]/z, \[x[0-9]+\]\n} 2 } } */
/* { dg-final { scan-assembler-times {\tld3h\t{z[0-9]+.h - z[0-9]+.h},
p[0-7]/z, \[x[0-9]+\]\n} 2 } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_15.c
b/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_15.c
index bc00267c8e7..814dbb3ae41 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_15.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_15.c
@@ -3,12 +3,12 @@
#include "struct_vect_14.c"
-/* { dg-final { scan-assembler-times {\tld2b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tld2b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tld3b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tld4b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+, x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tst2b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tld4b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tst2b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tst3b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tst4b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tst4b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tld2h\t{z[0-9]+.h - z[0-9]+.h},
p[0-7]/z, \[x[0-9]+\]\n} 2 } } */
/* { dg-final { scan-assembler-times {\tld3h\t{z[0-9]+.h - z[0-9]+.h},
p[0-7]/z, \[x[0-9]+\]\n} 2 } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_16.c
b/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_16.c
index 9e2a549f5e8..6ecf89b5442 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_16.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_16.c
@@ -3,12 +3,12 @@
#include "struct_vect_14.c"
-/* { dg-final { scan-assembler-times {\tld2b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tld2b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tld3b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tld4b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+, x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tst2b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tld4b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tst2b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tst3b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tst4b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tst4b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tld2h\t{z[0-9]+.h - z[0-9]+.h},
p[0-7]/z, \[x[0-9]+\]\n} 2 } } */
/* { dg-final { scan-assembler-times {\tld3h\t{z[0-9]+.h - z[0-9]+.h},
p[0-7]/z, \[x[0-9]+\]\n} 2 } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_17.c
b/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_17.c
index e791e2e12a6..571c6d0d33b 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_17.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/struct_vect_17.c
@@ -3,12 +3,12 @@
#include "struct_vect_14.c"
-/* { dg-final { scan-assembler-times {\tld2b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tld2b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tld3b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tld4b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+, x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tst2b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tld4b\t{z[0-9]+.b - z[0-9]+.b},
p[0-7]/z, \[x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tst2b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tst3b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
-/* { dg-final { scan-assembler-times {\tst4b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+, x[0-9]+\]\n} 1 } } */
+/* { dg-final { scan-assembler-times {\tst4b\t{z[0-9]+.b - z[0-9]+.b}, p[0-7],
\[x[0-9]+\]\n} 1 } } */
/* { dg-final { scan-assembler-times {\tld2h\t{z[0-9]+.h - z[0-9]+.h},
p[0-7]/z, \[x[0-9]+\]\n} 2 } } */
/* { dg-final { scan-assembler-times {\tld3h\t{z[0-9]+.h - z[0-9]+.h},
p[0-7]/z, \[x[0-9]+\]\n} 2 } } */
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index 80e78f7adf4..730dc0130c6 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -991,6 +991,51 @@ vect_min_prec_for_max_niters (loop_vec_info loop_vinfo,
unsigned int factor)
return wi::min_precision (max_ni * factor, UNSIGNED);
}
+/* true if the loop needs peeling or partial vectors when vectorized. */
+
+static bool
+vect_need_peeling_or_part_vects_p (loop_vec_info loop_vinfo)
+{
+ unsigned HOST_WIDE_INT const_vf;
+ HOST_WIDE_INT max_niter
+ = likely_max_stmt_executions_int (LOOP_VINFO_LOOP (loop_vinfo));
+
+ unsigned th = LOOP_VINFO_COST_MODEL_THRESHOLD (loop_vinfo);
+ if (!th && LOOP_VINFO_ORIG_LOOP_INFO (loop_vinfo))
+ th = LOOP_VINFO_COST_MODEL_THRESHOLD (LOOP_VINFO_ORIG_LOOP_INFO
+ (loop_vinfo));
+
+ if (LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
+ && LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo) >= 0)
+ {
+ /* Work out the (constant) number of iterations that need to be
+ peeled for reasons other than niters. */
+ unsigned int peel_niter = LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo);
+ if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo))
+ peel_niter += 1;
+ if (!multiple_p (LOOP_VINFO_INT_NITERS (loop_vinfo) - peel_niter,
+ LOOP_VINFO_VECT_FACTOR (loop_vinfo)))
+ return true;
+ }
+ else if (LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo)
+ /* ??? When peeling for gaps but not alignment, we could
+ try to check whether the (variable) niters is known to be
+ VF * N + 1. That's something of a niche case though. */
+ || LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo)
+ || !LOOP_VINFO_VECT_FACTOR (loop_vinfo).is_constant (&const_vf)
+ || ((tree_ctz (LOOP_VINFO_NITERS (loop_vinfo))
+ < (unsigned) exact_log2 (const_vf))
+ /* In case of versioning, check if the maximum number of
+ iterations is greater than th. If they are identical,
+ the epilogue is unnecessary. */
+ && (!LOOP_REQUIRES_VERSIONING (loop_vinfo)
+ || ((unsigned HOST_WIDE_INT) max_niter
+ > (th / const_vf) * const_vf))))
+ return true;
+
+ return false;
+}
+
/* Each statement in LOOP_VINFO can be masked where necessary. Check
whether we can actually generate the masks required. Return true if so,
storing the type of the scalar IV in LOOP_VINFO_RGROUP_COMPARE_TYPE. */
@@ -1967,44 +2012,10 @@ determine_peel_for_niter (loop_vec_info loop_vinfo)
{
LOOP_VINFO_PEELING_FOR_NITER (loop_vinfo) = false;
- unsigned HOST_WIDE_INT const_vf;
- HOST_WIDE_INT max_niter
- = likely_max_stmt_executions_int (LOOP_VINFO_LOOP (loop_vinfo));
-
- unsigned th = LOOP_VINFO_COST_MODEL_THRESHOLD (loop_vinfo);
- if (!th && LOOP_VINFO_ORIG_LOOP_INFO (loop_vinfo))
- th = LOOP_VINFO_COST_MODEL_THRESHOLD (LOOP_VINFO_ORIG_LOOP_INFO
- (loop_vinfo));
-
if (LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo))
/* The main loop handles all iterations. */
LOOP_VINFO_PEELING_FOR_NITER (loop_vinfo) = false;
- else if (LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
- && LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo) >= 0)
- {
- /* Work out the (constant) number of iterations that need to be
- peeled for reasons other than niters. */
- unsigned int peel_niter = LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo);
- if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo))
- peel_niter += 1;
- if (!multiple_p (LOOP_VINFO_INT_NITERS (loop_vinfo) - peel_niter,
- LOOP_VINFO_VECT_FACTOR (loop_vinfo)))
- LOOP_VINFO_PEELING_FOR_NITER (loop_vinfo) = true;
- }
- else if (LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo)
- /* ??? When peeling for gaps but not alignment, we could
- try to check whether the (variable) niters is known to be
- VF * N + 1. That's something of a niche case though. */
- || LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo)
- || !LOOP_VINFO_VECT_FACTOR (loop_vinfo).is_constant (&const_vf)
- || ((tree_ctz (LOOP_VINFO_NITERS (loop_vinfo))
- < (unsigned) exact_log2 (const_vf))
- /* In case of versioning, check if the maximum number of
- iterations is greater than th. If they are identical,
- the epilogue is unnecessary. */
- && (!LOOP_REQUIRES_VERSIONING (loop_vinfo)
- || ((unsigned HOST_WIDE_INT) max_niter
- > (th / const_vf) * const_vf))))
+ else if (vect_need_peeling_or_part_vects_p (loop_vinfo))
LOOP_VINFO_PEELING_FOR_NITER (loop_vinfo) = true;
}
@@ -2267,7 +2278,10 @@ start_over:
{
if (param_vect_partial_vector_usage == 0)
LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo) = false;
- else if (vect_verify_full_masking (loop_vinfo)
+ else if ((vect_verify_full_masking (loop_vinfo)
+ && vect_need_peeling_or_part_vects_p (loop_vinfo))
+ /* Don't use partial vectors if we don't need to peel the
+ loop. */
|| vect_verify_loop_lens (loop_vinfo))
{
/* The epilogue and other known niters less than VF
--
2.17.1
