MATCH: Add some more value_replacement simplifications to match

This moves a few more value_replacements simplifications to match.
/* a == 1 ? b : a * b -> a * b */
/* a == 1 ? b : b / a  -> b / a */
/* a == -1 ? b : a & b -> a & b */

Also adds a testcase to show can we catch these where value_replacement would not
(but other passes would).

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

gcc/ChangeLog:

	* match.pd (`a == 1 ? b : a OP b`): New pattern.
	(`a == -1 ? b : a & b`): New pattern.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/phi-opt-value-4.c: New test.

diff --git a/gcc/match.pd b/gcc/match.pd
index 22899c51a2f9ab1b86745916dec5576497099e43..070db9880ec5f4e8c3b45305b8d007e47a3478dd 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4159,6 +4159,24 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (cond (eq @0 integer_zerop) @1 (op@2 @1 @0))
    @2))
 
+/* a == 1 ? b : b / a  -> b / a */
+(for op (trunc_div ceil_div floor_div round_div exact_div)
+ (simplify
+  (cond (eq @0 integer_onep) @1 (op@2 @1 @0))
+   @2))
+
+/* a == 1 ? b : a * b -> a * b */
+(for op (mult)
+ (simplify
+  (cond (eq @0 integer_onep) @1 (op:c@2 @1 @0))
+   @2))
+
+/* a == -1 ? b : a & b -> a & b */
+(for op (bit_and)
+ (simplify
+  (cond (eq @0 integer_all_onesp) @1 (op:c@2 @1 @0))
+   @2))
+
 /* Simplifications of shift and rotates.  */
 
 (for rotate (lrotate rrotate)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-4.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-4.c
new file mode 100644 (file)
index 0000000..380082c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-4.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-fre3 -fdump-tree-phiopt1 -fdump-tree-optimized" } */
+
+[[gnu::const]]
+int constcall(int);
+
+int fdiv(int a, int b)
+{
+  int c = b/a;
+  int t = constcall(c);
+  int d;
+  if (a == 1) d = b; else d = c;
+  return constcall(d) + t;
+}
+int fmult(int a, int b)
+{
+  int c = b*a;
+  int t = constcall(c);
+  int d;
+  if (a == 1) d = b; else d = c;
+  return constcall(d) + t;
+}
+int fand(int a, int b)
+{
+  int c = b&a;
+  int t = constcall(c);
+  int d;
+  if (a == -1) d = b; else d = c;
+  return constcall(d) + t;
+}
+
+/* Should be able to optimize away the if statements in phiopt1. */
+/* { dg-final { scan-tree-dump-not "if " "phiopt1" } } */
+/* fre3 should be optimize each function to just `return constcall(a OP b) * 2;`. */
+/* { dg-final { scan-tree-dump-times "constcall " 3 "fre3" } } */
+/* { dg-final { scan-tree-dump-times "constcall " 3 "optimized" } } */