Hi All,

The following testcase:

int zoo1 (int a, int b, int c, int d)
{
   return (a > b ? c : d) & 1;
}

gets de-optimized by the front-end since somewhere around GCC 4.x due to a fix
that was added to fold_binary_op_with_conditional_arg.

The folding is supposed to succeed only if we have folded at least one of the
branches, however the check doesn't tests that all of the values are
non-constant.  So if one of the operators are a constant it accepts the folding.

This ends up folding

   return (a > b ? c : d) & 1;

into

   return (a > b ? c & 1 : d & 1);

and thus performing the AND twice.

change changes it to reject the folding if one of the arguments are a constant
and if the operations being performed are the same.

Secondly it adds a new match.pd rule to now also fold the opposite direction, so
it now also folds:

   return (a > b ? c & 1 : d & 1);

into

   return (a > b ? c : d) & 1;

Bootstrapped Regtested on aarch64-none-linux-gnu, x86_64-pc-linux-gnu
and <on-goin> issues.

Ok for master?

Thanks,
Tamar

gcc/ChangeLog:

	* fold-const.cc (fold_binary_op_with_conditional_arg): Add relaxation.
	* match.pd: Add ternary constant fold rule.
	* tree-cfg.cc (verify_gimple_assign_ternary): RHS1 of a COND_EXPR isn't
	a value but an expression itself. 

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/if-compare_3.c: New test.

--- inline copy of patch -- 
diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index 4f4ec81c8d4b6937ade3141a14c695b67c874c35..0ee083f290d12104969f1b335dc33917c97b4808 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -7212,7 +7212,9 @@ fold_binary_op_with_conditional_arg (location_t loc,
     }
 
   /* Check that we have simplified at least one of the branches.  */
-  if (!TREE_CONSTANT (arg) && !TREE_CONSTANT (lhs) && !TREE_CONSTANT (rhs))
+  if ((!TREE_CONSTANT (arg) && !TREE_CONSTANT (lhs) && !TREE_CONSTANT (rhs))
+      || (TREE_CONSTANT (arg) && TREE_CODE (lhs) == TREE_CODE (rhs)
+	  && !TREE_CONSTANT (lhs)))
     return NULL_TREE;
 
   return fold_build3_loc (loc, cond_code, type, test, lhs, rhs);
diff --git a/gcc/match.pd b/gcc/match.pd
index b225d36dc758f1581502c8d03761544bfd499c01..b61ed70e69b881a49177f10f20c1f92712bb8665 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4318,6 +4318,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (op @3 (vec_cond:s @0 @1 @2))
   (vec_cond @0 (op! @3 @1) (op! @3 @2))))
 
+/* Float out binary operations from branches if they can't be folded.
+   Fold (a ? (b op c) : (d op c)) --> (op (a ? b : d) c).  */
+(for op (plus mult min max bit_and bit_ior bit_xor minus lshift rshift rdiv
+	 trunc_div ceil_div floor_div round_div trunc_mod ceil_mod floor_mod
+	 round_mod)
+ (simplify
+  (cond @0 (op @1 @2) (op @3 @2))
+   (if (!FLOAT_TYPE_P (type) || !(HONOR_NANS (@1) && flag_trapping_math))
+    (op (cond @0 @1 @3) @2))))
+
 #if GIMPLE
 (match (nop_atomic_bit_test_and_p @0 @1 @4)
  (bit_and (convert?@4 (ATOMIC_FETCH_OR_XOR_N @2 INTEGER_CST@0 @3))
diff --git a/gcc/testsuite/gcc.target/aarch64/if-compare_3.c b/gcc/testsuite/gcc.target/aarch64/if-compare_3.c
new file mode 100644
index 0000000000000000000000000000000000000000..1d97da5c0d6454175881c219927471a567a6f0c7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/if-compare_3.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-O3 -std=c99" } */
+/* { dg-final { check-function-bodies "**" "" "" { target { le } } } } */
+
+/*
+**zoo:
+**	cmp	w0, w1
+**	csel	w0, w3, w2, le
+**	ret
+*/
+int zoo (int a, int b, int c, int d)
+{
+   return a > b ? c : d;
+}
+
+/*
+**zoo1:
+**	cmp	w0, w1
+**	csel	w0, w3, w2, le
+**	and	w0, w0, 1
+**	ret
+*/
+int zoo1 (int a, int b, int c, int d)
+{
+   return (a > b ? c : d) & 1;
+}
+
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index b19710392940cf469de52d006603ae1e3deb6b76..aaf1b29da5c598add25dad2c38b828eaa89c49ce 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -4244,7 +4244,9 @@ verify_gimple_assign_ternary (gassign *stmt)
       return true;
     }
 
-  if (!is_gimple_val (rhs1)
+  /* In a COND_EXPR the rhs1 is the condition and thus isn't
+     a gimple value by definition.  */
+  if ((!is_gimple_val (rhs1) && rhs_code != COND_EXPR)
       || !is_gimple_val (rhs2)
       || !is_gimple_val (rhs3))
     {




--