Drop Z from X + Z < Y + Z

2017-04-28  Marc Glisse  <marc.glisse@inria.fr>

gcc/
	* match.pd (X+Z OP Y+Z, X-Z OP Y-Z, Z-X OP Z-Y): New transformations.

gcc/testsuite/
	* gcc.dg/tree-ssa/cmpexactdiv-2.c: Update for X-Z OP Y-Z.

From-SVN: r247398

4 files changed, 58 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9f885b4..d1204f1 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2017-04-28  Marc Glisse  <marc.glisse@inria.fr>
+
+	* match.pd (X+Z OP Y+Z, X-Z OP Y-Z, Z-X OP Z-Y): New transformations.
+
 2017-04-28  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	* configure.ac (SYSTEM_HEADER_DIR, BUILD_SYSTEM_HEADER_DIR,
diff --git a/gcc/match.pd b/gcc/match.pd
index 44745df..e3d98ba 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1042,6 +1042,54 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (if (wi::gt_p(@2, 0, TYPE_SIGN (TREE_TYPE (@2))))
    (cmp @0 @1))))
 
+/* X + Z < Y + Z is the same as X < Y when there is no overflow.  */
+(for op (lt le ge gt)
+ (simplify
+  (op (plus:c @0 @2) (plus:c @1 @2))
+  (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+       && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
+   (op @0 @1))))
+/* For equality and subtraction, this is also true with wrapping overflow.  */
+(for op (eq ne minus)
+ (simplify
+  (op (plus:c @0 @2) (plus:c @1 @2))
+  (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+       && (TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))
+	   || TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0))))
+   (op @0 @1))))
+
+/* X - Z < Y - Z is the same as X < Y when there is no overflow.  */
+(for op (lt le ge gt)
+ (simplify
+  (op (minus @0 @2) (minus @1 @2))
+  (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+       && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
+   (op @0 @1))))
+/* For equality and subtraction, this is also true with wrapping overflow.  */
+(for op (eq ne minus)
+ (simplify
+  (op (minus @0 @2) (minus @1 @2))
+  (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+       && (TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))
+	   || TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0))))
+   (op @0 @1))))
+
+/* Z - X < Z - Y is the same as Y < X when there is no overflow.  */
+(for op (lt le ge gt)
+ (simplify
+  (op (minus @2 @0) (minus @2 @1))
+  (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+       && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
+   (op @1 @0))))
+/* For equality and subtraction, this is also true with wrapping overflow.  */
+(for op (eq ne minus)
+ (simplify
+  (op (minus @2 @0) (minus @2 @1))
+  (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+       && (TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))
+	   || TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0))))
+   (op @1 @0))))
+
 /* ((X inner_op C0) outer_op C1)
    With X being a tree where value_range has reasoned certain bits to always be
    zero throughout its computed value range,
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 499f780..92db79c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2017-04-28  Marc Glisse  <marc.glisse@inria.fr>
+
+	* gcc.dg/tree-ssa/cmpexactdiv-2.c: Update for X-Z OP Y-Z.
+
 2017-04-28  Tom de Vries  <tom@codesourcery.com>
 
 	* g++.dg/abi/bitfield3.C: Remove superfluous "" in
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-2.c b/gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-2.c
index e7f11b9..a41811c 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-2.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-2.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O -fdump-tree-optimized-raw" } */
+/* { dg-options "-O -fstrict-overflow -fdump-tree-optimized-raw" } */
 
 int f (long *a, long *b, long *c) {
     __PTRDIFF_TYPE__ l1 = b - a;
@@ -7,5 +7,5 @@ int f (long *a, long *b, long *c) {
     return l1 < l2;
 }
 
-/* Eventually we also want to remove all minus_expr.  */
+/* { dg-final { scan-tree-dump-not "minus_expr" "optimized" } } */
 /* { dg-final { scan-tree-dump-not "exact_div_expr" "optimized" } } */