Patchwork [(4/7)] Unsigned multiplies using wider signed multiplies

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Submitter Andrew Stubbs
Date July 14, 2011, 2:23 p.m.
Message ID <4E1EFBE7.6040606@codesourcery.com>
Download mbox | patch
Permalink /patch/104684/
State New
Headers show

Comments

Andrew Stubbs - July 14, 2011, 2:23 p.m.
On 12/07/11 15:07, Andrew Stubbs wrote:
> This update does the same thing as before, but updated for the changes
> earlier in the patch series. In particular, the build_and_insert_cast
> function and find_widening_optab_handler_and_mode changes have been
> moved up to patch 2.

And this update changes the way the casts are handled, partly because it 
got unwieldy towards the end of the patch series, and partly because I 
found a few bugs.

I've also ensured that it checks the precision of the types, rather than 
the mode size to ensure that it is bitfield safe.

OK?

Andrew
Richard Guenther - July 14, 2011, 2:25 p.m.
On Thu, Jul 14, 2011 at 4:23 PM, Andrew Stubbs <ams@codesourcery.com> wrote:
> On 12/07/11 15:07, Andrew Stubbs wrote:
>>
>> This update does the same thing as before, but updated for the changes
>> earlier in the patch series. In particular, the build_and_insert_cast
>> function and find_widening_optab_handler_and_mode changes have been
>> moved up to patch 2.
>
> And this update changes the way the casts are handled, partly because it got
> unwieldy towards the end of the patch series, and partly because I found a
> few bugs.
>
> I've also ensured that it checks the precision of the types, rather than the
> mode size to ensure that it is bitfield safe.
>
> OK?

Ok.

Thanks,
Richard.

> Andrew
>

Patch

2011-07-14  Andrew Stubbs  <ams@codesourcery.com>

	gcc/
	* tree-ssa-math-opts.c (convert_mult_to_widen): Convert
	unsupported unsigned multiplies to signed.
	(convert_plusminus_to_widen): Likewise.

	gcc/testsuite/
	* gcc.target/arm/wmul-6.c: New file.

--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/wmul-6.c
@@ -0,0 +1,10 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=armv7-a" } */
+
+long long
+foo (long long a, unsigned char *b, signed char *c)
+{
+  return a + (long long)*b * (long long)*c;
+}
+
+/* { dg-final { scan-assembler "smlal" } } */
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -2067,12 +2067,13 @@  is_widening_mult_p (gimple stmt,
 static bool
 convert_mult_to_widen (gimple stmt, gimple_stmt_iterator *gsi)
 {
-  tree lhs, rhs1, rhs2, type, type1, type2, tmp;
+  tree lhs, rhs1, rhs2, type, type1, type2, tmp = NULL;
   enum insn_code handler;
   enum machine_mode to_mode, from_mode, actual_mode;
   optab op;
   int actual_precision;
   location_t loc = gimple_location (stmt);
+  bool from_unsigned1, from_unsigned2;
 
   lhs = gimple_assign_lhs (stmt);
   type = TREE_TYPE (lhs);
@@ -2084,10 +2085,12 @@  convert_mult_to_widen (gimple stmt, gimple_stmt_iterator *gsi)
 
   to_mode = TYPE_MODE (type);
   from_mode = TYPE_MODE (type1);
+  from_unsigned1 = TYPE_UNSIGNED (type1);
+  from_unsigned2 = TYPE_UNSIGNED (type2);
 
-  if (TYPE_UNSIGNED (type1) && TYPE_UNSIGNED (type2))
+  if (from_unsigned1 && from_unsigned2)
     op = umul_widen_optab;
-  else if (!TYPE_UNSIGNED (type1) && !TYPE_UNSIGNED (type2))
+  else if (!from_unsigned1 && !from_unsigned2)
     op = smul_widen_optab;
   else
     op = usmul_widen_optab;
@@ -2096,22 +2099,45 @@  convert_mult_to_widen (gimple stmt, gimple_stmt_iterator *gsi)
 						  0, &actual_mode);
 
   if (handler == CODE_FOR_nothing)
-    return false;
+    {
+      if (op != smul_widen_optab)
+	{
+	  from_mode = GET_MODE_WIDER_MODE (from_mode);
+	  if (GET_MODE_SIZE (to_mode) <= GET_MODE_SIZE (from_mode))
+	    return false;
+
+	  op = smul_widen_optab;
+	  handler = find_widening_optab_handler_and_mode (op, to_mode,
+							  from_mode, 0,
+							  &actual_mode);
+
+	  if (handler == CODE_FOR_nothing)
+	    return false;
+
+	  from_unsigned1 = from_unsigned2 = false;
+	}
+      else
+	return false;
+    }
 
   /* Ensure that the inputs to the handler are in the correct precison
      for the opcode.  This will be the full mode size.  */
   actual_precision = GET_MODE_PRECISION (actual_mode);
-  if (actual_precision != TYPE_PRECISION (type1))
+  if (actual_precision != TYPE_PRECISION (type1)
+      || from_unsigned1 != TYPE_UNSIGNED (type1))
     {
       tmp = create_tmp_var (build_nonstandard_integer_type
-				(actual_precision, TYPE_UNSIGNED (type1)),
+				(actual_precision, from_unsigned1),
 			    NULL);
       rhs1 = build_and_insert_cast (gsi, loc, tmp, rhs1);
-
+    }
+  if (actual_precision != TYPE_PRECISION (type2)
+      || from_unsigned2 != TYPE_UNSIGNED (type2))
+    {
       /* Reuse the same type info, if possible.  */
-      if (TYPE_UNSIGNED (type1) != TYPE_UNSIGNED (type2))
+      if (!tmp || from_unsigned1 != from_unsigned2)
 	tmp = create_tmp_var (build_nonstandard_integer_type
-				(actual_precision, TYPE_UNSIGNED (type2)),
+				(actual_precision, from_unsigned2),
 			      NULL);
       rhs2 = build_and_insert_cast (gsi, loc, tmp, rhs2);
     }
@@ -2136,7 +2162,7 @@  convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple stmt,
 {
   gimple rhs1_stmt = NULL, rhs2_stmt = NULL;
   gimple conv1_stmt = NULL, conv2_stmt = NULL, conv_stmt;
-  tree type, type1, type2, tmp;
+  tree type, type1, type2, optype, tmp = NULL;
   tree lhs, rhs1, rhs2, mult_rhs1, mult_rhs2, add_rhs;
   enum tree_code rhs1_code = ERROR_MARK, rhs2_code = ERROR_MARK;
   optab this_optab;
@@ -2145,6 +2171,7 @@  convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple stmt,
   enum machine_mode to_mode, from_mode, actual_mode;
   location_t loc = gimple_location (stmt);
   int actual_precision;
+  bool from_unsigned1, from_unsigned2;
 
   lhs = gimple_assign_lhs (stmt);
   type = TREE_TYPE (lhs);
@@ -2238,9 +2265,21 @@  convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple stmt,
 
   to_mode = TYPE_MODE (type);
   from_mode = TYPE_MODE (type1);
+  from_unsigned1 = TYPE_UNSIGNED (type1);
+  from_unsigned2 = TYPE_UNSIGNED (type2);
 
-  if (TYPE_UNSIGNED (type1) != TYPE_UNSIGNED (type2))
-    return false;
+  /* There's no such thing as a mixed sign madd yet, so use a wider mode.  */
+  if (from_unsigned1 != from_unsigned2)
+    {
+      enum machine_mode mode = GET_MODE_WIDER_MODE (from_mode);
+      if (GET_MODE_PRECISION (mode) < GET_MODE_PRECISION (to_mode))
+	{
+	  from_mode = mode;
+	  from_unsigned1 = from_unsigned2 = false;
+	}
+      else
+	return false;
+    }
 
   /* If there was a conversion between the multiply and addition
      then we need to make sure it fits a multiply-and-accumulate.
@@ -2248,6 +2287,7 @@  convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple stmt,
      value.  */
   if (conv_stmt)
     {
+      /* We use the original, unmodified data types for this.  */
       tree from_type = TREE_TYPE (gimple_assign_rhs1 (conv_stmt));
       tree to_type = TREE_TYPE (gimple_assign_lhs (conv_stmt));
       int data_size = TYPE_PRECISION (type1) + TYPE_PRECISION (type2);
@@ -2272,7 +2312,8 @@  convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple stmt,
   /* Verify that the machine can perform a widening multiply
      accumulate in this mode/signedness combination, otherwise
      this transformation is likely to pessimize code.  */
-  this_optab = optab_for_tree_code (wmult_code, type1, optab_default);
+  optype = build_nonstandard_integer_type (from_mode, from_unsigned1);
+  this_optab = optab_for_tree_code (wmult_code, optype, optab_default);
   handler = find_widening_optab_handler_and_mode (this_optab, to_mode,
 						  from_mode, 0, &actual_mode);
 
@@ -2282,13 +2323,21 @@  convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple stmt,
   /* Ensure that the inputs to the handler are in the correct precison
      for the opcode.  This will be the full mode size.  */
   actual_precision = GET_MODE_PRECISION (actual_mode);
-  if (actual_precision != TYPE_PRECISION (type1))
+  if (actual_precision != TYPE_PRECISION (type1)
+      || from_unsigned1 != TYPE_UNSIGNED (type1))
     {
       tmp = create_tmp_var (build_nonstandard_integer_type
-				(actual_precision, TYPE_UNSIGNED (type1)),
+				(actual_precision, from_unsigned1),
 			    NULL);
-
       mult_rhs1 = build_and_insert_cast (gsi, loc, tmp, mult_rhs1);
+    }
+  if (actual_precision != TYPE_PRECISION (type2)
+      || from_unsigned2 != TYPE_UNSIGNED (type2))
+    {
+      if (!tmp || from_unsigned1 != from_unsigned2)
+	tmp = create_tmp_var (build_nonstandard_integer_type
+				(actual_precision, from_unsigned2),
+			      NULL);
       mult_rhs2 = build_and_insert_cast (gsi, loc, tmp, mult_rhs2);
     }