Hi!
The following optimizations also can't handle nop conversions between the
inner and outer addition/subtraction, and even -fwrapv doesn't help there,
only simplify-rtx.c is able to do something about those.
Implemented thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
ok for trunk?
2019-12-04 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/92734
* match.pd ((A +- B) - A -> +- B, (A +- B) -+ B -> A,
A - (A +- B) -> -+ B, A +- (B -+ A) -> +- B): Handle nop_convert.
* gcc.dg/tree-ssa/pr92734-2.c: New test.
--- gcc/match.pd.jj 2019-12-03 10:20:00.244913801 +0100
+++ gcc/match.pd 2019-12-03 13:36:01.084435697 +0100
@@ -2159,20 +2159,26 @@ (define_operator_list COND_TERNARY
/* A - (A +- B) -> -+ B */
/* A +- (B -+ A) -> +- B */
(simplify
- (minus (plus:c @0 @1) @0)
- @1)
+ (minus (nop_convert (plus:c (nop_convert @0) @1)) @0)
+ (view_convert @1))
(simplify
- (minus (minus @0 @1) @0)
- (negate @1))
+ (minus (nop_convert (minus (nop_convert @0) @1)) @0)
+ (if (!ANY_INTEGRAL_TYPE_P (type)
+ || TYPE_OVERFLOW_WRAPS (type))
+ (negate (view_convert @1))
+ (view_convert (negate @1))))
(simplify
- (plus:c (minus @0 @1) @1)
- @0)
+ (plus:c (nop_convert (minus @0 (nop_convert @1))) @1)
+ (view_convert @0))
(simplify
- (minus @0 (plus:c @0 @1))
- (negate @1))
+ (minus @0 (nop_convert (plus:c (nop_convert @0) @1)))
+ (if (!ANY_INTEGRAL_TYPE_P (type)
+ || TYPE_OVERFLOW_WRAPS (type))
+ (negate (view_convert @1))
+ (view_convert (negate @1))))
(simplify
- (minus @0 (minus @0 @1))
- @1)
+ (minus @0 (nop_convert (minus (nop_convert @0) @1)))
+ (view_convert @1))
/* (A +- B) + (C - A) -> C +- B */
/* (A + B) - (A - C) -> B + C */
/* More cases are handled with comparisons. */
--- gcc/testsuite/gcc.dg/tree-ssa/pr92734-2.c.jj 2019-12-03
13:56:05.036800119 +0100
+++ gcc/testsuite/gcc.dg/tree-ssa/pr92734-2.c 2019-12-03 13:55:43.035140773
+0100
@@ -0,0 +1,76 @@
+/* PR tree-optimization/92734 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* Verify there are no binary additions or subtractions left. There can
+ be just casts and negations. */
+/* { dg-final { scan-tree-dump-not " \[+-] " "optimized" } } */
+
+int
+f1 (int x, unsigned y)
+{
+ int a = x + y;
+ return a - x;
+}
+
+unsigned
+f2 (unsigned x, int y)
+{
+ unsigned a = (int) x + y;
+ return a - x;
+}
+
+int
+f3 (int x, unsigned y)
+{
+ int a = x - y;
+ return a - x;
+}
+
+unsigned
+f4 (unsigned x, int y)
+{
+ unsigned a = (int) x - y;
+ return a - x;
+}
+
+int
+f5 (unsigned x, int y)
+{
+ int a = x - y;
+ return a + y;
+}
+
+unsigned
+f6 (int x, unsigned y)
+{
+ unsigned a = x - (int) y;
+ return a + y;
+}
+
+int
+f7 (int x, unsigned y)
+{
+ int a = x + y;
+ return x - a;
+}
+
+unsigned
+f8 (unsigned x, int y)
+{
+ unsigned a = (int) x + y;
+ return x - a;
+}
+
+int
+f9 (int x, unsigned y)
+{
+ int a = x - y;
+ return x - a;
+}
+
+unsigned
+f10 (unsigned x, int y)
+{
+ unsigned a = (int) x - y;
+ return x - a;
+}
Jakub
