From 4d9db4bdd458a4b526f59e4bc5bbd549d3861cea Mon Sep 17 00:00:00 2001
From: Tamar Christina <tamar.christina@arm.com>
Date: Mon, 12 Dec 2022 15:21:39 +0000
Subject: [PATCH] middle-end: simplify complex if expressions where comparisons
are inverse of one another.
This optimizes the following sequence
((a < b) & c) | ((a >= b) & d)
into
(a < b ? c : d) & 1
for scalar and on vector we can omit the & 1.
Also recognizes
(-(a < b) & c) | (-(a >= b) & d)
into
a < b ? c : d
This changes the code generation from
zoo2:
cmp w0, w1
cset w0, lt
cset w1, ge
and w0, w0, w2
and w1, w1, w3
orr w0, w0, w1
ret
into
cmp w0, w1
csel w0, w2, w3, lt
and w0, w0, 1
ret
and significantly reduces the number of selects we have to do in the vector
code.
gcc/ChangeLog:
* match.pd: Add new rule.
gcc/testsuite/ChangeLog:
* gcc.target/aarch64/if-compare_1.c: New test.
* gcc.target/aarch64/if-compare_2.c: New test.
---
gcc/match.pd | 55 +++++++++++
.../gcc.target/aarch64/if-compare_1.c | 47 +++++++++
.../gcc.target/aarch64/if-compare_2.c | 96 +++++++++++++++++++
3 files changed, 198 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/aarch64/if-compare_1.c
create mode 100644 gcc/testsuite/gcc.target/aarch64/if-compare_2.c
diff --git a/gcc/match.pd b/gcc/match.pd
index fdba5833beb8..c48fe2d6bf20 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1906,6 +1906,61 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(if (INTEGRAL_TYPE_P (type))
(bit_and @0 @1)))
+(for cmp (tcc_comparison)
+ icmp (inverted_tcc_comparison)
+ /* Fold (((a < b) & c) | ((a >= b) & d)) into (a < b ? c : d) & 1. */
+ (simplify
+ (bit_ior
+ (bit_and:c (convert? (cmp@0 @01 @02)) @3)
+ (bit_and:c (convert? (icmp@4 @01 @02)) @5))
+ (if (INTEGRAL_TYPE_P (type)
+ /* The scalar version has to be canonicalized after vectorization
+ because it makes unconditional loads conditional ones, which
+ means we lose vectorization because the loads may trap. */
+ && canonicalize_math_after_vectorization_p ())
+ (bit_and (cond @0 @3 @5) { build_one_cst (type); })))
+
+ /* Fold ((-(a < b) & c) | (-(a >= b) & d)) into a < b ? c : d. This is
+ canonicalized further and we recognize the conditional form:
+ (a < b ? c : 0) | (a >= b ? d : 0) into a < b ? c : d. */
+ (simplify
+ (bit_ior
+ (cond (cmp@0 @01 @02) @3 zerop)
+ (cond (icmp@4 @01 @02) @5 zerop))
+ (if (INTEGRAL_TYPE_P (type)
+ /* The scalar version has to be canonicalized after vectorization
+ because it makes unconditional loads conditional ones, which
+ means we lose vectorization because the loads may trap. */
+ && canonicalize_math_after_vectorization_p ())
+ (cond @0 @3 @5)))
+
+ /* Vector Fold (((a < b) & c) | ((a >= b) & d)) into a < b ? c : d.
+ and ((~(a < b) & c) | (~(a >= b) & d)) into a < b ? c : d. */
+ (simplify
+ (bit_ior
+ (bit_and:c (vec_cond:s (cmp@0 @6 @7) @4 @5) @2)
+ (bit_and:c (vec_cond:s (icmp@1 @6 @7) @4 @5) @3))
+ (if (integer_zerop (@5))
+ (switch
+ (if (integer_onep (@4))
+ (bit_and (vec_cond @0 @2 @3) @4))
+ (if (integer_minus_onep (@4))
+ (vec_cond @0 @2 @3)))
+ (if (integer_zerop (@4))
+ (switch
+ (if (integer_onep (@5))
+ (bit_and (vec_cond @0 @3 @2) @5))
+ (if (integer_minus_onep (@5))
+ (vec_cond @0 @3 @2))))))
+
+ /* Scalar Vectorized Fold ((-(a < b) & c) | (-(a >= b) & d))
+ into a < b ? d : c. */
+ (simplify
+ (bit_ior
+ (vec_cond:s (cmp@0 @4 @5) @2 integer_zerop)
+ (vec_cond:s (icmp@1 @4 @5) @3 integer_zerop))
+ (vec_cond @0 @2 @3)))
+
/* Transform X & -Y into X * Y when Y is { 0 or 1 }. */
(simplify
(bit_and:c (convert? (negate zero_one_valued_p@0)) @1)
diff --git a/gcc/testsuite/gcc.target/aarch64/if-compare_1.c b/gcc/testsuite/gcc.target/aarch64/if-compare_1.c
new file mode 100644
index 000000000000..53bbd779a30e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/if-compare_1.c
@@ -0,0 +1,47 @@
+/* { dg-do run } */
+/* { dg-additional-options "-O -save-temps" } */
+/* { dg-final { check-function-bodies "**" "" "" { target { le } } } } */
+
+extern void abort ();
+
+/*
+**zoo1:
+** cmp w0, w1
+** csel w0, w2, w3, lt
+** and w0, w0, 1
+** ret
+*/
+__attribute((noipa, noinline))
+int zoo1 (int a, int b, int c, int d)
+{
+ return ((a < b) & c) | ((a >= b) & d);
+}
+
+/*
+**zoo2:
+** cmp w0, w1
+** csel w0, w2, w3, lt
+** ret
+*/
+__attribute((noipa, noinline))
+int zoo2 (int a, int b, int c, int d)
+{
+ return (-(a < b) & c) | (-(a >= b) & d);
+}
+
+int main ()
+{
+ if (zoo1 (-3, 3, 5, 8) != 1)
+ abort ();
+
+ if (zoo1 (3, -3, 5, 8) != 0)
+ abort ();
+
+ if (zoo2 (-3, 3, 5, 8) != 5)
+ abort ();
+
+ if (zoo2 (3, -3, 5, 8) != 8)
+ abort ();
+
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/if-compare_2.c b/gcc/testsuite/gcc.target/aarch64/if-compare_2.c
new file mode 100644
index 000000000000..14988abac459
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/if-compare_2.c
@@ -0,0 +1,96 @@
+/* { dg-do run } */
+/* { dg-additional-options "-O3 -std=c99 -save-temps" } */
+/* { dg-final { check-function-bodies "**" "" "" { target { le } } } } */
+
+#pragma GCC target "+nosve"
+
+#include <string.h>
+
+typedef int v4si __attribute__ ((vector_size (16)));
+
+/*
+**foo1:
+** cmgt v0.4s, v1.4s, v0.4s
+** bsl v0.16b, v2.16b, v3.16b
+** ret
+*/
+v4si foo1 (v4si a, v4si b, v4si c, v4si d) {
+ return ((a < b) & c) | ((a >= b) & d);
+}
+
+/*
+**foo2:
+** cmgt v0.4s, v1.4s, v0.4s
+** bsl v0.16b, v3.16b, v2.16b
+** ret
+*/
+v4si foo2 (v4si a, v4si b, v4si c, v4si d) {
+ return (~(a < b) & c) | (~(a >= b) & d);
+}
+
+
+/**
+**bar1:
+**...
+** cmge v[0-9]+.4s, v[0-9]+.4s, v[0-9]+.4s
+** bsl v[0-9]+.16b, v[0-9]+.16b, v[0-9]+.16b
+** and v[0-9]+.16b, v[0-9]+.16b, v[0-9]+.16b
+**...
+*/
+void bar1 (int * restrict a, int * restrict b, int * restrict c,
+ int * restrict d, int * restrict res, int n)
+{
+ for (int i = 0; i < (n & -4); i++)
+ res[i] = ((a[i] < b[i]) & c[i]) | ((a[i] >= b[i]) & d[i]);
+}
+
+/**
+**bar2:
+**...
+** cmge v[0-9]+.4s, v[0-9]+.4s, v[0-9]+.4s
+** bsl v[0-9]+.16b, v[0-9]+.16b, v[0-9]+.16b
+**...
+*/
+void bar2 (int * restrict a, int * restrict b, int * restrict c,
+ int * restrict d, int * restrict res, int n)
+{
+ for (int i = 0; i < (n & -4); i++)
+ res[i] = (-(a[i] < b[i]) & c[i]) | (-(a[i] >= b[i]) & d[i]);
+}
+
+extern void abort ();
+
+int main ()
+{
+
+ v4si a = { -3, -3, -3, -3 };
+ v4si b = { 3, 3, 3, 3 };
+ v4si c = { 5, 5, 5, 5 };
+ v4si d = { 8, 8, 8, 8 };
+
+ v4si res1 = foo1 (a, b, c, d);
+ if (memcmp (&res1, &c, 16UL) != 0)
+ abort ();
+
+ v4si res2 = foo2 (a, b, c, d);
+ if (memcmp (&res2, &d, 16UL) != 0)
+ abort ();
+
+ int ar[4] = { -3, -3, -3, -3 };
+ int br[4] = { 3, 3, 3, 3 };
+ int cr[4] = { 5, 5, 5, 5 };
+ int dr[4] = { 8, 8, 8, 8 };
+
+ int exp1[4] = { 1, 1, 1, 1 };
+ int res3[4];
+ bar1 ((int*)&ar, (int*)&br, (int*)&cr, (int*)&dr, (int*)&res3, 4);
+ if (memcmp (&res3, &exp1, 16UL) != 0)
+ abort ();
+
+ int res4[4];
+ bar2 ((int*)&ar, (int*)&br, (int*)&cr, (int*)&dr, (int*)&res4, 4);
+ if (memcmp (&res4, &cr, 16UL) != 0)
+ abort ();
+
+ return 0;
+}
--
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