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* [gcc r12-4922] middle-end: convert negate + right shift into compare greater.
@ 2021-11-04 17:37 Tamar Christina
0 siblings, 0 replies; only message in thread
From: Tamar Christina @ 2021-11-04 17:37 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:d70720c2382e687e192a9d666e80acb41bfda856
commit r12-4922-gd70720c2382e687e192a9d666e80acb41bfda856
Author: Tamar Christina <tamar.christina@arm.com>
Date: Thu Nov 4 17:32:09 2021 +0000
middle-end: convert negate + right shift into compare greater.
This turns an inversion of the sign bit + arithmetic right shift into a
comparison with 0.
i.e.
void fun1(int32_t *x, int n)
{
for (int i = 0; i < (n & -16); i++)
x[i] = (-x[i]) >> 31;
}
now generates:
.L3:
ldr q0, [x0]
cmgt v0.4s, v0.4s, #0
str q0, [x0], 16
cmp x0, x1
bne .L3
instead of:
.L3:
ldr q0, [x0]
neg v0.4s, v0.4s
sshr v0.4s, v0.4s, 31
str q0, [x0], 16
cmp x0, x1
bne .L3
gcc/ChangeLog:
* match.pd: New negate+shift pattern.
gcc/testsuite/ChangeLog:
* gcc.dg/signbit-2.c: New test.
* gcc.dg/signbit-3.c: New test.
* gcc.dg/signbit-4.c: New test.
* gcc.dg/signbit-5.c: New test.
* gcc.dg/signbit-6.c: New test.
* gcc.target/aarch64/signbit-1.c: New test.
Diff:
---
gcc/match.pd | 36 +++++++++++++-
gcc/testsuite/gcc.dg/signbit-2.c | 19 ++++++++
gcc/testsuite/gcc.dg/signbit-3.c | 13 +++++
gcc/testsuite/gcc.dg/signbit-4.c | 65 +++++++++++++++++++++++++
gcc/testsuite/gcc.dg/signbit-5.c | 65 +++++++++++++++++++++++++
gcc/testsuite/gcc.dg/signbit-6.c | 72 ++++++++++++++++++++++++++++
gcc/testsuite/gcc.target/aarch64/signbit-1.c | 20 ++++++++
7 files changed, 289 insertions(+), 1 deletion(-)
diff --git a/gcc/match.pd b/gcc/match.pd
index 651982c28fe..917833dd14b 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -37,7 +37,8 @@ along with GCC; see the file COPYING3. If not see
integer_pow2p
uniform_integer_cst_p
HONOR_NANS
- uniform_vector_p)
+ uniform_vector_p
+ expand_vec_cmp_expr_p)
/* Operator lists. */
(define_operator_list tcc_comparison
@@ -831,6 +832,39 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
{ tree utype = unsigned_type_for (type); }
(convert (rshift (lshift (convert:utype @0) @2) @3))))))
+/* Fold (-x >> C) into -(x > 0) where C = precision(type) - 1. */
+(for cst (INTEGER_CST VECTOR_CST)
+ (simplify
+ (rshift (negate:s @0) cst@1)
+ (if (!TYPE_UNSIGNED (type)
+ && TYPE_OVERFLOW_UNDEFINED (type))
+ (with { tree stype = TREE_TYPE (@1);
+ tree bt = truth_type_for (type);
+ tree zeros = build_zero_cst (type);
+ tree cst = NULL_TREE; }
+ (switch
+ /* Handle scalar case. */
+ (if (INTEGRAL_TYPE_P (type)
+ /* If we apply the rule to the scalar type before vectorization
+ we will enforce the result of the comparison being a bool
+ which will require an extra AND on the result that will be
+ indistinguishable from when the user did actually want 0
+ or 1 as the result so it can't be removed. */
+ && canonicalize_math_after_vectorization_p ()
+ && wi::eq_p (wi::to_wide (@1), TYPE_PRECISION (type) - 1))
+ (negate (convert (gt @0 { zeros; }))))
+ /* Handle vector case. */
+ (if (VECTOR_INTEGER_TYPE_P (type)
+ /* First check whether the target has the same mode for vector
+ comparison results as it's operands do. */
+ && TYPE_MODE (bt) == TYPE_MODE (type)
+ /* Then check to see if the target is able to expand the comparison
+ with the given type later on, otherwise we may ICE. */
+ && expand_vec_cmp_expr_p (type, bt, GT_EXPR)
+ && (cst = uniform_integer_cst_p (@1)) != NULL
+ && wi::eq_p (wi::to_wide (cst), element_precision (type) - 1))
+ (view_convert (gt:bt @0 { zeros; }))))))))
+
/* Fold (C1/X)*C2 into (C1*C2)/X. */
(simplify
(mult (rdiv@3 REAL_CST@0 @1) REAL_CST@2)
diff --git a/gcc/testsuite/gcc.dg/signbit-2.c b/gcc/testsuite/gcc.dg/signbit-2.c
new file mode 100644
index 00000000000..fc0157cbc5c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/signbit-2.c
@@ -0,0 +1,19 @@
+/* { dg-do assemble } */
+/* { dg-options "-O3 --save-temps -fdump-tree-optimized" } */
+
+#include <stdint.h>
+
+void fun1(int32_t *x, int n)
+{
+ for (int i = 0; i < (n & -16); i++)
+ x[i] = (-x[i]) >> 31;
+}
+
+void fun2(int32_t *x, int n)
+{
+ for (int i = 0; i < (n & -16); i++)
+ x[i] = (-x[i]) >> 30;
+}
+
+/* { dg-final { scan-tree-dump-times {\s+>\s+\{ 0, 0, 0, 0 \}} 1 optimized } } */
+/* { dg-final { scan-tree-dump-not {\s+>>\s+31} optimized } } */
diff --git a/gcc/testsuite/gcc.dg/signbit-3.c b/gcc/testsuite/gcc.dg/signbit-3.c
new file mode 100644
index 00000000000..19e9c06c349
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/signbit-3.c
@@ -0,0 +1,13 @@
+/* { dg-do assemble } */
+/* { dg-options "-O1 --save-temps -fdump-tree-optimized" } */
+
+#include <stdint.h>
+
+void fun1(int32_t *x, int n)
+{
+ for (int i = 0; i < (n & -16); i++)
+ x[i] = (-x[i]) >> 31;
+}
+
+/* { dg-final { scan-tree-dump-times {\s+>\s+0;} 1 optimized } } */
+/* { dg-final { scan-tree-dump-not {\s+>>\s+31} optimized } } */
diff --git a/gcc/testsuite/gcc.dg/signbit-4.c b/gcc/testsuite/gcc.dg/signbit-4.c
new file mode 100644
index 00000000000..bc459ba60a7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/signbit-4.c
@@ -0,0 +1,65 @@
+/* { dg-do run } */
+/* { dg-options "-O1 -fwrapv" } */
+
+#include <stdint.h>
+#include <limits.h>
+#include <stdio.h>
+
+#ifndef N
+#define N 65
+#endif
+
+#ifndef TYPE
+#define TYPE int32_t
+#endif
+
+#ifndef DEBUG
+#define DEBUG 1
+#endif
+
+#define BASE ((TYPE) -1 < 0 ? -126 : 4)
+
+__attribute__ ((noinline, noipa))
+void fun1(TYPE *x, int n)
+{
+ for (int i = 0; i < n; i++)
+ x[i] = (-x[i]) >> 31;
+}
+
+__attribute__ ((noinline, noipa, optimize("O0")))
+void fun2(TYPE *x, int n)
+{
+ for (int i = 0; i < n; i++)
+ x[i] = (-x[i]) >> 31;
+}
+
+int main ()
+{
+ TYPE a[N];
+ TYPE b[N];
+
+ a[0] = INT_MIN;
+ b[0] = INT_MIN;
+
+ for (int i = 1; i < N; ++i)
+ {
+ a[i] = BASE + i * 13;
+ b[i] = BASE + i * 13;
+ if (DEBUG)
+ printf ("%d: 0x%x\n", i, a[i]);
+ }
+
+ fun1 (a, N);
+ fun2 (b, N);
+
+ for (int i = 0; i < N; ++i)
+ {
+ if (DEBUG)
+ printf ("%d = 0x%x == 0x%x\n", i, a[i], b[i]);
+
+ if (a[i] != b[i])
+ __builtin_abort ();
+ }
+ return 0;
+}
+
diff --git a/gcc/testsuite/gcc.dg/signbit-5.c b/gcc/testsuite/gcc.dg/signbit-5.c
new file mode 100644
index 00000000000..22a92704773
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/signbit-5.c
@@ -0,0 +1,65 @@
+/* { dg-do run } */
+/* { dg-options "-O3" } */
+
+#include <stdint.h>
+#include <limits.h>
+#include <stdio.h>
+
+#ifndef N
+#define N 65
+#endif
+
+#ifndef TYPE
+#define TYPE int32_t
+#endif
+
+#ifndef DEBUG
+#define DEBUG 1
+#endif
+
+#define BASE ((TYPE) -1 < 0 ? -126 : 4)
+
+__attribute__ ((noinline, noipa))
+void fun1(TYPE *x, int n)
+{
+ for (int i = 0; i < n; i++)
+ x[i] = (-x[i]) >> 31;
+}
+
+__attribute__ ((noinline, noipa, optimize("O1")))
+void fun2(TYPE *x, int n)
+{
+ for (int i = 0; i < n; i++)
+ x[i] = (-x[i]) >> 31;
+}
+
+int main ()
+{
+ TYPE a[N];
+ TYPE b[N];
+
+ a[0] = INT_MIN;
+ b[0] = INT_MIN;
+
+ for (int i = 1; i < N; ++i)
+ {
+ a[i] = BASE + i * 13;
+ b[i] = BASE + i * 13;
+ if (DEBUG)
+ printf ("%d: 0x%x\n", i, a[i]);
+ }
+
+ fun1 (a, N);
+ fun2 (b, N);
+
+ for (int i = 0; i < N; ++i)
+ {
+ if (DEBUG)
+ printf ("%d = 0x%x == 0x%x\n", i, a[i], b[i]);
+
+ if (a[i] != b[i])
+ __builtin_abort ();
+ }
+ return 0;
+}
+
diff --git a/gcc/testsuite/gcc.dg/signbit-6.c b/gcc/testsuite/gcc.dg/signbit-6.c
new file mode 100644
index 00000000000..da186624cfa
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/signbit-6.c
@@ -0,0 +1,72 @@
+/* { dg-do run } */
+/* { dg-options "-O1" } */
+
+#include <stdint.h>
+#include <limits.h>
+#include <stdio.h>
+
+#ifndef N
+#define N 65
+#endif
+
+#ifndef TYPE
+#define TYPE int32_t
+#endif
+
+#ifndef DEBUG
+#define DEBUG 1
+#endif
+
+#define BASE ((TYPE) -1 < 0 ? -126 : 4)
+
+__attribute__ ((noinline, noipa))
+void fun1(TYPE *x, int n)
+{
+ for (int i = 0; i < n; i++)
+ x[i] = (-x[i]) >> 31;
+}
+
+__attribute__ ((noinline, noipa, optimize("O0")))
+void fun2(TYPE *x, int n)
+{
+ for (int i = 0; i < n; i++)
+ x[i] = (-x[i]) >> 31;
+}
+
+int main ()
+{
+ TYPE a[N];
+ TYPE b[N];
+
+ a[0] = INT_MIN;
+ b[0] = INT_MIN;
+
+ for (int i = 1; i < N; ++i)
+ {
+ a[i] = BASE + i * 13;
+ b[i] = BASE + i * 13;
+ if (DEBUG)
+ printf ("%d: 0x%x\n", i, a[i]);
+ }
+
+ fun1 (a, N);
+ fun2 (b, N);
+
+ if (DEBUG)
+ printf ("%d = 0x%x == 0x%x\n", 0, a[0], b[0]);
+
+ if (a[0] != 0x0 || b[0] != -1)
+ __builtin_abort ();
+
+
+ for (int i = 1; i < N; ++i)
+ {
+ if (DEBUG)
+ printf ("%d = 0x%x == 0x%x\n", i, a[i], b[i]);
+
+ if (a[i] != b[i])
+ __builtin_abort ();
+ }
+ return 0;
+}
+
diff --git a/gcc/testsuite/gcc.target/aarch64/signbit-1.c b/gcc/testsuite/gcc.target/aarch64/signbit-1.c
new file mode 100644
index 00000000000..a5654d139cb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/signbit-1.c
@@ -0,0 +1,20 @@
+/* { dg-do assemble } */
+/* { dg-options "-O3 --save-temps" } */
+
+#include <stdint.h>
+
+#pragma GCC target "+nosve"
+
+void fun1(int32_t *x, int n)
+{
+ for (int i = 0; i < (n & -16); i++)
+ x[i] = (-x[i]) >> 31;
+}
+
+void fun2(int32_t *x, int n)
+{
+ for (int i = 0; i < (n & -16); i++)
+ x[i] = (-x[i]) >> 30;
+}
+
+/* { dg-final { scan-assembler-times {\tcmgt\t} 1 } } */
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