match.pd: Decrease number of nop conversions around bitwise ops [PR94718]

On the following testcase, there are in *.optimized dump 14 nop conversions
(from signed to unsigned and back), while this patch decreases that number
to just 4; for bitwise ops it really doesn't matter if they are performed in
signed or unsigned, so the patch (in GIMPLE only, there are some comments
about it being undesirable during GENERIC earlier), if it sees both
bitop operands nop converted from the same types performs the bitop in their
non-converted type and converts the result (i.e. 2 conversions into 1),
similarly, if a bitop has one operand nop converted from something, the
other not and the result is converted back to the type of the nop converted
operand before conversion, it is possible to replace those 2 conversions
with just a single conversion of the other operand.

2020-05-04  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/94718
	* match.pd (bitop (convert @0) (convert? @1)): For GIMPLE, if we can,
	replace two nop conversions on bit_{and,ior,xor} argument
	and result with just one conversion on the result or another argument.

	* gcc.dg/tree-ssa/pr94718-3.c: New test.

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 47eef982a59f27bb7e76de9ed0e319f76c77ad89..036a40303087d0bb627b901054fec642018e534b 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,10 @@
 2020-05-04  Jakub Jelinek  <jakub@redhat.com>
 
+       PR tree-optimization/94718
+       * match.pd (bitop (convert @0) (convert? @1)): For GIMPLE, if we can,
+       replace two nop conversions on bit_{and,ior,xor} argument
+       and result with just one conversion on the result or another argument.
+
        PR tree-optimization/94718
        * fold-const.c (fold_binary_loc): Move (X & C) eqne (Y & C)
        -> (X ^ Y) & C eqne 0 optimization to ...

diff --git a/gcc/match.pd b/gcc/match.pd
index 123e670f9eeac781e13e9b93b6c8789e84a5aa43..929be14e8b7dfdd2ce9545bd9cee953cb99d32ec 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1311,7 +1311,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
    We combine the above two cases by using a conditional convert.  */
 (for bitop (bit_and bit_ior bit_xor)
  (simplify
-  (bitop (convert @0) (convert? @1))
+  (bitop (convert@2 @0) (convert?@3 @1))
   (if (((TREE_CODE (@1) == INTEGER_CST
         && INTEGRAL_TYPE_P (TREE_TYPE (@0))
         && int_fits_type_p (@1, TREE_TYPE (@0)))
@@ -1330,8 +1330,24 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
           || GET_MODE_CLASS (TYPE_MODE (type)) != MODE_INT
           /* Or if the precision of TO is not the same as the precision
              of its mode.  */
-          || !type_has_mode_precision_p (type)))
-   (convert (bitop @0 (convert @1))))))
+          || !type_has_mode_precision_p (type)
+          /* In GIMPLE, getting rid of 2 conversions for one new results
+             in smaller IL.  */
+          || (GIMPLE
+              && TREE_CODE (@1) != INTEGER_CST
+              && tree_nop_conversion_p (type, TREE_TYPE (@0))
+              && single_use (@2)
+              && single_use (@3))))
+   (convert (bitop @0 (convert @1)))))
+ /* In GIMPLE, getting rid of 2 conversions for one new results
+    in smaller IL.  */
+ (simplify
+  (convert (bitop:cs@2 (nop_convert:s @0) @1))
+  (if (GIMPLE
+       && TREE_CODE (@1) != INTEGER_CST
+       && tree_nop_conversion_p (type, TREE_TYPE (@2))
+       && types_match (type, @0))
+   (bitop @0 (convert @1)))))
 
 (for bitop (bit_and bit_ior)
      rbitop (bit_ior bit_and)

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 100870acedb458a2ff9a4430b2ae43544af36dbf..09979b5749c7fad642d4ce81395943beab03b52d 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2020-05-04  Jakub Jelinek  <jakub@redhat.com>
 
+       PR tree-optimization/94718
+       * gcc.dg/tree-ssa/pr94718-3.c: New test.
+
        PR tree-optimization/94718
        * gcc.dg/tree-ssa/pr94718-1.c: New test.
        * gcc.dg/tree-ssa/pr94718-2.c: New test.

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr94718-3.c b/gcc/testsuite/gcc.dg/tree-ssa/pr94718-3.c
new file mode 100644 (file)
index 0000000..d1fb4a6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr94718-3.c
@@ -0,0 +1,45 @@
+/* PR tree-optimization/94718 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-ipa-icf -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-times " \\\(int\\\) " 2 "optimized" } } */
+/* { dg-final { scan-tree-dump-times " \\\(unsigned int\\\) " 2 "optimized" } } */
+
+int
+f1 (int x, int y)
+{
+  return (int) ((unsigned) x | (unsigned) y);
+}
+
+int
+f2 (int x, int y)
+{
+  unsigned a = x;
+  unsigned b = y;
+  return a | b;
+}
+
+int
+f3 (int x, unsigned y)
+{
+  return (int) ((unsigned) x | y);
+}
+
+int
+f4 (int x, unsigned y)
+{
+  unsigned a = x;
+  return a | y;
+}
+
+unsigned
+f5 (int x, unsigned y)
+{
+  return (unsigned) (x | (int) y);
+}
+
+unsigned
+f6 (int x, unsigned y)
+{
+  int a = y;
+  return x | a;
+}