[PATCH 1/4] Canonicalize argument order for commutative functions

[Richard Sandiford]

This patch uses information about internal functions to canonicalize
the argument order of calls.

Tested on aarch64-linux-gnu and x86_64-linux-gnu.  OK to install?

Richard


gcc/
	* gimple-fold.c: Include internal-fn.h.
	(fold_stmt_1): If a function maps to an internal one, use
	first_commutative_argument to canonicalize the order of
	commutative arguments.

gcc/testsuite/
	* gcc.dg/fmax-fmin-1.c: New test.
---
 gcc/gimple-fold.c                  | 25 ++++++++++++++++++++++---
 gcc/testsuite/gcc.dg/fmax-fmin-1.c | 18 ++++++++++++++++++
 2 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/fmax-fmin-1.c

diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index a937f130815..6a7d4507c89 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -69,6 +69,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "varasm.h"
 #include "memmodel.h"
 #include "optabs.h"
+#include "internal-fn.h"
 
 enum strlen_range_kind {
   /* Compute the exact constant string length.  */
@@ -6140,18 +6141,36 @@ fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace, tree (*valueize) (tree))
       break;
     case GIMPLE_CALL:
       {
-	for (i = 0; i < gimple_call_num_args (stmt); ++i)
+	gcall *call = as_a<gcall *> (stmt);
+	for (i = 0; i < gimple_call_num_args (call); ++i)
 	  {
-	    tree *arg = gimple_call_arg_ptr (stmt, i);
+	    tree *arg = gimple_call_arg_ptr (call, i);
 	    if (REFERENCE_CLASS_P (*arg)
 		&& maybe_canonicalize_mem_ref_addr (arg))
 	      changed = true;
 	  }
-	tree *lhs = gimple_call_lhs_ptr (stmt);
+	tree *lhs = gimple_call_lhs_ptr (call);
 	if (*lhs
 	    && REFERENCE_CLASS_P (*lhs)
 	    && maybe_canonicalize_mem_ref_addr (lhs))
 	  changed = true;
+	if (*lhs)
+	  {
+	    combined_fn cfn = gimple_call_combined_fn (call);
+	    internal_fn ifn = associated_internal_fn (cfn, TREE_TYPE (*lhs));
+	    int opno = first_commutative_argument (ifn);
+	    if (opno >= 0)
+	      {
+		tree arg1 = gimple_call_arg (call, opno);
+		tree arg2 = gimple_call_arg (call, opno + 1);
+		if (tree_swap_operands_p (arg1, arg2))
+		  {
+		    gimple_call_set_arg (call, opno, arg2);
+		    gimple_call_set_arg (call, opno + 1, arg1);
+		    changed = true;
+		  }
+	      }
+	  }
 	break;
       }
     case GIMPLE_ASM:
diff --git a/gcc/testsuite/gcc.dg/fmax-fmin-1.c b/gcc/testsuite/gcc.dg/fmax-fmin-1.c
new file mode 100644
index 00000000000..e7e0518d8bb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fmax-fmin-1.c
@@ -0,0 +1,18 @@
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+void
+f1 (double *res, double x, double y)
+{
+  res[0] = __builtin_fmax (x, y);
+  res[1] = __builtin_fmax (y, x);
+}
+
+void
+f2 (double *res, double x, double y)
+{
+  res[0] = __builtin_fmin (x, y);
+  res[1] = __builtin_fmin (y, x);
+}
+
+/* { dg-final { scan-tree-dump-times {__builtin_fmax} 1 "optimized" } } */
+/* { dg-final { scan-tree-dump-times {__builtin_fmin} 1 "optimized" } } */
-- 
2.25.1