forwprop: Pattern recognize more rotates [PR94344]

The following patch adjusts simplify_rotate to recognize more rotates,
basically we allow even some same precision integral -> integral
conversions, with the requirement that the RSHIFT_EXPR operand has to be
done in unsigned type (i.e. logical right shift), so that we compensate for
the combiner no longer being able to simplify those into rotates on some
targets.

2020-03-31  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/94344
	* tree-ssa-forwprop.c (simplify_rotate): Handle also same precision
	conversions, either on both operands of |^+ or just one.  Handle
	also extra same precision conversion on RSHIFT_EXPR first operand
	provided RSHIFT_EXPR is performed in unsigned type.

	* gcc.dg/pr94344.c: New test.

4 files changed, 110 insertions, 4 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 101956a..f7d1ccf 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2020-03-31  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/94344
+	* tree-ssa-forwprop.c (simplify_rotate): Handle also same precision
+	conversions, either on both operands of |^+ or just one.  Handle
+	also extra same precision conversion on RSHIFT_EXPR first operand
+	provided RSHIFT_EXPR is performed in unsigned type.
+
 2020-03-30  David Malcolm  <dmalcolm@redhat.com>
 
 	* lra.c (finish_insn_code_data_once): Set the array elements
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c72aa9a..14faa3f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-31  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/94344
+	* gcc.dg/pr94344.c: New test.
+
 2020-03-30  David Malcolm  <dmalcolm@redhat.com>
 
 	* jit.dg/all-non-failing-tests.h: Add test-empty.c
diff --git a/gcc/testsuite/gcc.dg/pr94344.c b/gcc/testsuite/gcc.dg/pr94344.c
new file mode 100644
index 0000000..361e16e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr94344.c
@@ -0,0 +1,53 @@
+/* PR rtl-optimization/94344 */
+/* { dg-do compile { target { ilp32 || lp64 } } } */
+/* { dg-options "-O2 -fdump-tree-forwprop1" } */
+/* { dg-final { scan-tree-dump-times " r>> 27;" 4 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-times " r>> 59;" 4 "forwprop1" } } */
+
+int
+f1 (int x)
+{
+  return (x << 5) | (int)((unsigned int)x >> 27);
+}
+
+unsigned int
+f2 (int x)
+{
+  return (x << 5) | ((unsigned int)x >> 27);
+}
+
+long long int
+f3 (long long int x)
+{
+  return (x << 5) | (long long int)((unsigned long long int)x >> 59);
+}
+
+unsigned long long int
+f4 (long long int x)
+{
+  return (x << 5) | ((unsigned long long int)x >> 59);
+}
+
+int
+f5 (int x)
+{
+  return (int)((unsigned int)x >> 27) | (x << 5);
+}
+
+unsigned int
+f6 (int x)
+{
+  return ((unsigned int)x >> 27) | (x << 5);
+}
+
+long long int
+f7 (long long int x)
+{
+  return (long long int)((unsigned long long int)x >> 59) | (x << 5);
+}
+
+unsigned long long int
+f8 (long long int x)
+{
+  return ((unsigned long long int)x >> 59) | (x << 5);
+}
diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index 234c1f7..e7eaa18 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -1562,14 +1562,14 @@ simplify_rotate (gimple_stmt_iterator *gsi)
   for (i = 0; i < 2; i++)
     defcodefor_name (arg[i], &def_code[i], &def_arg1[i], &def_arg2[i]);
 
-  /* Look through narrowing conversions.  */
+  /* Look through narrowing (or same precision) conversions.  */
   if (CONVERT_EXPR_CODE_P (def_code[0])
       && CONVERT_EXPR_CODE_P (def_code[1])
       && INTEGRAL_TYPE_P (TREE_TYPE (def_arg1[0]))
       && INTEGRAL_TYPE_P (TREE_TYPE (def_arg1[1]))
       && TYPE_PRECISION (TREE_TYPE (def_arg1[0]))
 	 == TYPE_PRECISION (TREE_TYPE (def_arg1[1]))
-      && TYPE_PRECISION (TREE_TYPE (def_arg1[0])) > TYPE_PRECISION (rtype)
+      && TYPE_PRECISION (TREE_TYPE (def_arg1[0])) >= TYPE_PRECISION (rtype)
       && has_single_use (arg[0])
       && has_single_use (arg[1]))
     {
@@ -1579,6 +1579,21 @@ simplify_rotate (gimple_stmt_iterator *gsi)
 	  defcodefor_name (arg[i], &def_code[i], &def_arg1[i], &def_arg2[i]);
 	}
     }
+  else
+    {
+      /* Handle signed rotate; the RSHIFT_EXPR has to be done
+	 in unsigned type but LSHIFT_EXPR could be signed.  */
+      i = (def_code[0] == LSHIFT_EXPR || def_code[0] == RSHIFT_EXPR);
+      if (CONVERT_EXPR_CODE_P (def_code[i])
+	  && (def_code[1 - i] == LSHIFT_EXPR || def_code[1 - i] == RSHIFT_EXPR)
+	  && INTEGRAL_TYPE_P (TREE_TYPE (def_arg1[i]))
+	  && TYPE_PRECISION (rtype) == TYPE_PRECISION (TREE_TYPE (def_arg1[i]))
+	  && has_single_use (arg[i]))
+	{
+	  arg[i] = def_arg1[i];
+	  defcodefor_name (arg[i], &def_code[i], &def_arg1[i], &def_arg2[i]);
+	}
+    }
 
   /* One operand has to be LSHIFT_EXPR and one RSHIFT_EXPR.  */
   for (i = 0; i < 2; i++)
@@ -1608,8 +1623,33 @@ simplify_rotate (gimple_stmt_iterator *gsi)
   if (!operand_equal_for_phi_arg_p (def_arg1[0], def_arg1[1])
       || !types_compatible_p (TREE_TYPE (def_arg1[0]),
 			      TREE_TYPE (def_arg1[1])))
-    return false;
-  if (!TYPE_UNSIGNED (TREE_TYPE (def_arg1[0])))
+    {
+      if ((TYPE_PRECISION (TREE_TYPE (def_arg1[0]))
+	   != TYPE_PRECISION (TREE_TYPE (def_arg1[1])))
+	  || (TYPE_UNSIGNED (TREE_TYPE (def_arg1[0]))
+	      == TYPE_UNSIGNED (TREE_TYPE (def_arg1[1]))))
+	return false;
+
+      /* Handle signed rotate; the RSHIFT_EXPR has to be done
+	 in unsigned type but LSHIFT_EXPR could be signed.  */
+      i = def_code[0] != RSHIFT_EXPR;
+      if (!TYPE_UNSIGNED (TREE_TYPE (def_arg1[i])))
+	return false;
+
+      tree tem;
+      enum tree_code code;
+      defcodefor_name (def_arg1[i], &code, &tem, NULL);
+      if (!CONVERT_EXPR_CODE_P (code)
+	  || !INTEGRAL_TYPE_P (TREE_TYPE (tem))
+	  || TYPE_PRECISION (TREE_TYPE (tem)) != TYPE_PRECISION (rtype))
+	return false;
+      def_arg1[i] = tem;
+      if (!operand_equal_for_phi_arg_p (def_arg1[0], def_arg1[1])
+	  || !types_compatible_p (TREE_TYPE (def_arg1[0]),
+				  TREE_TYPE (def_arg1[1])))
+	return false;
+    }
+  else if (!TYPE_UNSIGNED (TREE_TYPE (def_arg1[0])))
     return false;
 
   /* CNT1 + CNT2 == B case above.  */