From: Kyrylo Tkachov <[email protected]>
The minimum and the maximum of two values add up to the sum of those
values, so subtracting one of them from the sum yields the other one.
That identity holds in modular arithmetic, so it needs only the guards
the neighbouring (x + y) - (x | y) rule uses.
int f (int a, int b) { int mn = a < b ? a : b; return (a + b) - mn; }
aarch64 -O2:
before after
cmp w1, w0 cmp w1, w0
add w2, w1, w0 csel w0, w1, w0, ge
csel w0, w1, w0, le
sub w0, w2, w0
Bootstrapped and tested on aarch64-none-linux-gnu.
Ok for trunk?
Thanks,
Kyrill
gcc/ChangeLog:
* match.pd ((x + y) - minmax (x, y)): New simplification.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/minmax-sum-1.c: New test.
Signed-off-by: Kyrylo Tkachov <[email protected]>
---
gcc/match.pd | 11 +++++++++++
gcc/testsuite/gcc.dg/tree-ssa/minmax-sum-1.c | 18 ++++++++++++++++++
2 files changed, 29 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/minmax-sum-1.c
diff --git a/gcc/match.pd b/gcc/match.pd
index 72169a7a666..3c789e41493 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -2048,6 +2048,17 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
&& !TYPE_SATURATING (type))
(res @0 @1))))
+/* (x + y) - min (x, y) -> max (x, y)
+ (x + y) - max (x, y) -> min (x, y)
+ The sum of the minimum and the maximum is the sum of the operands. */
+(for minmax (min max)
+ maxmin (max min)
+ (simplify
+ (minus (plus @0 @1) (minmax:c @0 @1))
+ (if (ANY_INTEGRAL_TYPE_P (type)
+ && !TYPE_OVERFLOW_SANITIZED (type) && !TYPE_OVERFLOW_TRAPS (type))
+ (maxmin @0 @1))))
+
/* (x | y) - y -> (x & ~y) */
(simplify
(minus (bit_ior:cs @0 @1) @1)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-sum-1.c
b/gcc/testsuite/gcc.dg/tree-ssa/minmax-sum-1.c
new file mode 100644
index 00000000000..47a78abd0fa
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-sum-1.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+/* The sum of the minimum and the maximum is the sum of the operands. */
+
+int f1 (int a, int b) { int mn = a < b ? a : b; return (a + b) - mn; }
+int f2 (int a, int b) { int mx = a < b ? b : a; return (a + b) - mx; }
+unsigned int f3 (unsigned int a, unsigned int b)
+{
+ unsigned int mn = a < b ? a : b;
+ return (a + b) - mn;
+}
+long f4 (long a, long b) { long mx = a < b ? b : a; return (b + a) - mx; }
+
+/* { dg-final { scan-tree-dump-times "MAX_EXPR" 2 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "MIN_EXPR" 2 "optimized" } } */
+/* { dg-final { scan-tree-dump-not " \\+ " "optimized" } } */
+/* { dg-final { scan-tree-dump-not " - " "optimized" } } */
--
2.50.1 (Apple Git-155)
