MATCH: Add some more value_replacement simplifications (a != 0 ? expr : 0) to match

This adds a few more of what is currently done in phiopt's value_replacement
to match. I noticed this when I was hooking up phiopt's value_replacement
code to use match and disabling the old code. But this can be done
independently from the hooking up phiopt's value_replacement as phiopt
is already hooked up for simplified versions already.

/* a != 0 ? a / b : 0  -> a / b iff b is nonzero. */
/* a != 0 ? a * b : 0 -> a * b */
/* a != 0 ? a & b : 0 -> a & b */

We prefer the `cond ? a : 0` forms to allow optimization of `a * cond` which
uses that form.

Bootstrapped and tested on x86_64-linux-gnu with no regressions.

	PR tree-optimization/114894

gcc/ChangeLog:

	* match.pd (`a != 0 ? a / b : 0`): New pattern.
	(`a != 0 ? a * b : 0`): New pattern.
	(`a != 0 ? a & b : 0`): New pattern.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/phi-opt-value-5.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

diff --git a/gcc/match.pd b/gcc/match.pd
index d401e7503e62cde441877f0a61511d3e97ad146f..03a03c31233c3c4c4bc6898125cb537c8ec8d6b9 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4290,6 +4290,24 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (cond (eq @0 integer_all_onesp) @1 (op:c@2 @1 @0))
    @2))
 
+/* a != 0 ? a / b : 0  -> a / b iff b is nonzero. */
+(for op (trunc_div ceil_div floor_div round_div exact_div)
+ (simplify
+  (cond (ne @0 integer_zerop) (op@2 @3 @1) integer_zerop )
+   (if (bitwise_equal_p (@0, @3)
+        && tree_expr_nonzero_p (@1))
+    @2)))
+
+/* Note we prefer the != case here
+   as (a != 0) * (a * b) will generate that version. */
+/* a != 0 ? a * b : 0 -> a * b */
+/* a != 0 ? a & b : 0 -> a & b */
+(for op (mult bit_and)
+ (simplify
+  (cond (ne @0 integer_zerop) (op:c@2 @1 @3) integer_zerop)
+  (if (bitwise_equal_p (@0, @3))
+   @2)))
+
 /* Simplifications of shift and rotates.  */
 
 (for rotate (lrotate rrotate)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-5.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-5.c
new file mode 100644 (file)
index 0000000..8062eb1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-5.c
@@ -0,0 +1,39 @@
+/* { dg-do compile } */
+/* PR treee-optimization/114894 */
+/* Phi-OPT should be able to optimize these without sinking being invoked. */
+/* { dg-options "-O -fdump-tree-phiopt2 -fdump-tree-phiopt3 -fdump-tree-optimized -fno-tree-sink" } */
+
+int fmul1(int a, int b)
+{
+  int c = a * b;
+  if (a != 0)
+    return c;
+  return 0;
+}
+
+
+int fand1(int a, int b)
+{
+  int c = a & b;
+  if (a != 0)
+    return c;
+  return 0;
+}
+
+
+void g(int);
+
+int fdiv1(int a, int b)
+{
+  int d = b|1;
+  g(d);
+  int c = a / d;
+  return a != 0 ? c : 0;
+}
+
+/* fdiv1 requires until later than phiopt2 to be able to detect that
+   d is non-zero. to be able to remove the conditional.  */
+/* { dg-final { scan-tree-dump-times "goto" 2 "phiopt2" } } */
+/* { dg-final { scan-tree-dump-not "goto" "phiopt3" } } */
+/* { dg-final { scan-tree-dump-not "goto" "optimized" } } */
+