[gcc r12-1055] Add a couple of A?CST1:CST2 match and simplify optimizations

[gcc r12-1055] Add a couple of A?CST1:CST2 match and simplify optimizations

[Andrew Pinski]

https://gcc.gnu.org/g:b6bdd7a4cb41ee057f2d064fffcb00f23ce6b497

commit r12-1055-gb6bdd7a4cb41ee057f2d064fffcb00f23ce6b497
Author: Andrew Pinski <apinski@marvell.com>
Date:   Sun May 16 13:07:06 2021 -0700

    Add a couple of A?CST1:CST2 match and simplify optimizations
    
    Instead of some of the more manual optimizations inside phi-opt,
    it would be good idea to do a lot of the heavy lifting inside match
    and simplify instead. In the process, this moves the three simple
    A?CST1:CST2 (where CST1 or CST2 is zero) simplifications.
    
    OK? Boostrapped and tested on x86_64-linux-gnu with no regressions.
    
    Differences from V1:
    * Use bit_xor 1 instead of bit_not to fix the problem with boolean types
    which are not 1 bit precision.
    
    Thanks,
    Andrew Pinski
    
    gcc:
            * match.pd (A?CST1:CST2): Add simplifcations for A?0:+-1, A?+-1:0,
            A?POW2:0 and A?0:POW2.

Diff:
---
 gcc/match.pd | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/gcc/match.pd b/gcc/match.pd
index 1fc6b7b1557..ad6b057c56d 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3711,6 +3711,47 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
    (if (integer_all_onesp (@1) && integer_zerop (@2))
     @0))))
 
+/* A few simplifications of "a ? CST1 : CST2". */
+/* NOTE: Only do this on gimple as the if-chain-to-switch
+   optimization depends on the gimple to have if statements in it. */
+#if GIMPLE
+(simplify
+ (cond @0 INTEGER_CST@1 INTEGER_CST@2)
+ (switch
+  (if (integer_zerop (@2))
+   (switch
+    /* a ? 1 : 0 -> a if 0 and 1 are integral types. */
+    (if (integer_onep (@1))
+     (convert (convert:boolean_type_node @0)))
+    /* a ? -1 : 0 -> -a. */
+    (if (integer_all_onesp (@1))
+     (negate (convert (convert:boolean_type_node @0))))
+    /* a ? powerof2cst : 0 -> a << (log2(powerof2cst)) */
+    (if (!POINTER_TYPE_P (type) && integer_pow2p (@1))
+     (with {
+       tree shift = build_int_cst (integer_type_node, tree_log2 (@1));
+      }
+      (lshift (convert (convert:boolean_type_node @0)) { shift; })))))
+  (if (integer_zerop (@1))
+   (with {
+      tree booltrue = constant_boolean_node (true, boolean_type_node);
+    }
+    (switch
+     /* a ? 0 : 1 -> !a. */
+     (if (integer_onep (@2))
+      (convert (bit_xor (convert:boolean_type_node @0) { booltrue; } )))
+     /* a ? -1 : 0 -> -(!a). */
+     (if (integer_all_onesp (@2))
+      (negate (convert (bit_xor (convert:boolean_type_node @0) { booltrue; } ))))
+     /* a ? powerof2cst : 0 -> (!a) << (log2(powerof2cst)) */
+     (if (!POINTER_TYPE_P (type) && integer_pow2p (@2))
+      (with {
+	tree shift = build_int_cst (integer_type_node, tree_log2 (@2));
+       }
+       (lshift (convert (bit_xor (convert:boolean_type_node @0) { booltrue; } ))
+        { shift; }))))))))
+#endif
+
 /* Simplification moved from fold_cond_expr_with_comparison.  It may also
    be extended.  */
 /* This pattern implements two kinds simplification: