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[55/67] Use scalar_int_mode in simplify_const_unary_operation

Message ID 87vautfcsh.fsf@e105548-lin.cambridge.arm.com
State New
Headers show

Commit Message

Richard Sandiford Dec. 9, 2016, 1:32 p.m. UTC 
The main scalar integer block in simplify_const_unary_operation
had the condition:

  if (CONST_SCALAR_INT_P (op) && width > 0)

where "width > 0" was a roundabout way of testing != VOIDmode.
This patch replaces it with a check for a scalar_int_mode instead.
It also uses the number of bits in the input rather than the output
mode to determine the result of a "count ... bits in zero" operation.
(At the momemnt these modes have to be the same, but it still seems
conceptually wrong to use the number of bits in the output mode.)

The handling of float->integer ops also checked "width > 0",
but this was redundant with the earlier check for MODE_INT.

These changes require the rtl wi:: routines to take machine_mode_enums,
to avoid an ambiguity when using scalar_int_modes instead of
machine_modes.  The problem is that machine_mode_enum (like all enums)
can be implicitly converted to an integer, and so the mode classes can
indirectly be converted to an integer too.  (And this is useful when
modes are used as array indices, for example.)  So when scalar_int_mode
was used, the non-rtl wi:: candidates that take integer precisions
instead of modes had the same rank as the machine_mode ones.

gcc/
2016-11-24  Richard Sandiford  <richard.sandiford@arm.com>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

	* rtl.h (wi::shwi): Take a machine_mode_enum rather than
	a machine_mode.
	(wi::min_value): Likewise.
	(wi::max_value): Likewise,
	* simplify-rtx.c (simplify_const_unary_operation): Use
	is_a <scalar_int_mode> instead of checking for a nonzero
	precision.  Forcibly convert op_mode to a scalar_int_mode
	in that case.  More clearly differentiate the operand and
	result modes and use the former when deciding what the value
	of a count-bits operation should be.  Use is_int_mode instead
	of checking for a MODE_INT.  Remove redundant check for whether
	this mode has a zero precision.
diff mbox

Patch

diff --git a/gcc/rtl.h b/gcc/rtl.h
index e65020a..a5ca103 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -2139,13 +2139,13 @@  wi::int_traits <rtx_mode_t>::decompose (HOST_WIDE_INT *,
 
 namespace wi
 {
-  hwi_with_prec shwi (HOST_WIDE_INT, machine_mode mode);
-  wide_int min_value (machine_mode, signop);
-  wide_int max_value (machine_mode, signop);
+  hwi_with_prec shwi (HOST_WIDE_INT, machine_mode_enum);
+  wide_int min_value (machine_mode_enum, signop);
+  wide_int max_value (machine_mode_enum, signop);
 }
 
 inline wi::hwi_with_prec
-wi::shwi (HOST_WIDE_INT val, machine_mode mode)
+wi::shwi (HOST_WIDE_INT val, machine_mode_enum mode)
 {
   return shwi (val, GET_MODE_PRECISION (mode));
 }
@@ -2153,7 +2153,7 @@  wi::shwi (HOST_WIDE_INT val, machine_mode mode)
 /* Produce the smallest number that is represented in MODE.  The precision
    is taken from MODE and the sign from SGN.  */
 inline wide_int
-wi::min_value (machine_mode mode, signop sgn)
+wi::min_value (machine_mode_enum mode, signop sgn)
 {
   return min_value (GET_MODE_PRECISION (mode), sgn);
 }
@@ -2161,7 +2161,7 @@  wi::min_value (machine_mode mode, signop sgn)
 /* Produce the largest number that is represented in MODE.  The precision
    is taken from MODE and the sign from SGN.  */
 inline wide_int
-wi::max_value (machine_mode mode, signop sgn)
+wi::max_value (machine_mode_enum mode, signop sgn)
 {
   return max_value (GET_MODE_PRECISION (mode), sgn);
 }
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index f4997bf..465e02a 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -1683,7 +1683,7 @@  rtx
 simplify_const_unary_operation (enum rtx_code code, machine_mode mode,
 				rtx op, machine_mode op_mode)
 {
-  unsigned int width = GET_MODE_PRECISION (mode);
+  scalar_int_mode result_mode;
 
   if (code == VEC_DUPLICATE)
     {
@@ -1798,10 +1798,13 @@  simplify_const_unary_operation (enum rtx_code code, machine_mode mode,
       return const_double_from_real_value (d, mode);
     }
 
-  if (CONST_SCALAR_INT_P (op) && width > 0)
+  if (CONST_SCALAR_INT_P (op) && is_a <scalar_int_mode> (mode, &result_mode))
     {
+      unsigned int width = GET_MODE_PRECISION (result_mode);
       wide_int result;
-      machine_mode imode = op_mode == VOIDmode ? mode : op_mode;
+      scalar_int_mode imode = (op_mode == VOIDmode
+			       ? result_mode
+			       : as_a <scalar_int_mode> (op_mode));
       rtx_mode_t op0 = rtx_mode_t (op, imode);
       int int_value;
 
@@ -1830,35 +1833,35 @@  simplify_const_unary_operation (enum rtx_code code, machine_mode mode,
 	  break;
 
 	case FFS:
-	  result = wi::shwi (wi::ffs (op0), mode);
+	  result = wi::shwi (wi::ffs (op0), result_mode);
 	  break;
 
 	case CLZ:
 	  if (wi::ne_p (op0, 0))
 	    int_value = wi::clz (op0);
-	  else if (! CLZ_DEFINED_VALUE_AT_ZERO (mode, int_value))
-	    int_value = GET_MODE_PRECISION (mode);
-	  result = wi::shwi (int_value, mode);
+	  else if (! CLZ_DEFINED_VALUE_AT_ZERO (imode, int_value))
+	    int_value = GET_MODE_PRECISION (imode);
+	  result = wi::shwi (int_value, result_mode);
 	  break;
 
 	case CLRSB:
-	  result = wi::shwi (wi::clrsb (op0), mode);
+	  result = wi::shwi (wi::clrsb (op0), result_mode);
 	  break;
 
 	case CTZ:
 	  if (wi::ne_p (op0, 0))
 	    int_value = wi::ctz (op0);
-	  else if (! CTZ_DEFINED_VALUE_AT_ZERO (mode, int_value))
-	    int_value = GET_MODE_PRECISION (mode);
-	  result = wi::shwi (int_value, mode);
+	  else if (! CTZ_DEFINED_VALUE_AT_ZERO (imode, int_value))
+	    int_value = GET_MODE_PRECISION (imode);
+	  result = wi::shwi (int_value, result_mode);
 	  break;
 
 	case POPCOUNT:
-	  result = wi::shwi (wi::popcount (op0), mode);
+	  result = wi::shwi (wi::popcount (op0), result_mode);
 	  break;
 
 	case PARITY:
-	  result = wi::shwi (wi::parity (op0), mode);
+	  result = wi::shwi (wi::parity (op0), result_mode);
 	  break;
 
 	case BSWAP:
@@ -1879,7 +1882,7 @@  simplify_const_unary_operation (enum rtx_code code, machine_mode mode,
 	  return 0;
 	}
 
-      return immed_wide_int_const (result, mode);
+      return immed_wide_int_const (result, result_mode);
     }
 
   else if (CONST_DOUBLE_AS_FLOAT_P (op) 
@@ -1936,9 +1939,9 @@  simplify_const_unary_operation (enum rtx_code code, machine_mode mode,
     }
   else if (CONST_DOUBLE_AS_FLOAT_P (op)
 	   && SCALAR_FLOAT_MODE_P (GET_MODE (op))
-	   && GET_MODE_CLASS (mode) == MODE_INT
-	   && width > 0)
+	   && is_int_mode (mode, &result_mode))
     {
+      unsigned int width = GET_MODE_PRECISION (result_mode);
       /* Although the overflow semantics of RTL's FIX and UNSIGNED_FIX
 	 operators are intentionally left unspecified (to ease implementation
 	 by target backends), for consistency, this routine implements the