Simple reassoc transforms in match.pd

2017-06-27  Marc Glisse  <marc.glisse@inria.fr>

gcc/
	* match.pd ((A+-B)+(C-A), (A+B)-(A-C)): New transformations.

gcc/testsuite/
	* gcc.dg/tree-ssa/assoc-1.c: New file.

From-SVN: r249686

gcc/ChangeLog

 2017-06-27  Marc Glisse  <marc.glisse@inria.fr>
 
+	* match.pd ((A+-B)+(C-A), (A+B)-(A-C)): New transformations.
+
+2017-06-27  Marc Glisse  <marc.glisse@inria.fr>
+
 	* builtin-types.def (BT_FENV_T_PTR, BT_CONST_FENV_T_PTR,
 	BT_FEXCEPT_T_PTR, BT_CONST_FEXCEPT_T_PTR): New primitive types.
 	(BT_FN_INT_FENV_T_PTR, BT_FN_INT_CONST_FENV_T_PTR,

gcc/match.pd

@@ -1321,6 +1321,18 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (simplify
    (minus @0 (minus @0 @1))
    @1)
+  /* (A +- B) + (C - A)   -> C +- B */
+  /* (A +  B) - (A - C)   -> B + C */
+  /* More cases are handled with comparisons.  */
+  (simplify
+   (plus:c (plus:c @0 @1) (minus @2 @0))
+   (plus @2 @1))
+  (simplify
+   (plus:c (minus @0 @1) (minus @2 @0))
+   (minus @2 @1))
+  (simplify
+   (minus (plus:c @0 @1) (minus @0 @2))
+   (plus @1 @2))
 
   /* (A +- CST1) +- CST2 -> A + CST3
      Use view_convert because it is safe for vectors and equivalent for

gcc/testsuite/ChangeLog

+2017-06-27  Marc Glisse  <marc.glisse@inria.fr>
+
+	* gcc.dg/tree-ssa/assoc-1.c: New file.
+
 2017-06-27  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/62046

gcc/testsuite/gcc.dg/tree-ssa/assoc-1.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized-raw -fno-tree-reassoc" } */
+
+int f0(int a,int b,int c){
+  int d = a + b;
+  int e = c + b;
+  return d - e;
+}
+int f1(int a,int b,int c){
+  int d = a + b;
+  int e = b - c;
+  return d - e;
+}
+int f2(int a,int b,int c){
+  int d = a + b;
+  int e = c - b;
+  return e + d;
+}
+int f3(int a,int b,int c){
+  int d = a - b;
+  int e = c - b;
+  return d - e;
+}
+int f4(int a,int b,int c){
+  int d = b - a;
+  int e = c - b;
+  return e + d;
+}
+
+/* { dg-final { scan-tree-dump-times "plus_expr" 2 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "minus_expr" 3 "optimized" } } */