re PR middle-end/323 (optimized code gives strange floating point results)

	PR rtl-optimization/323
	* c-common.c (c_fully_fold, convert_and_check,
	c_common_truthvalue_conversion): Handle EXCESS_PRECISION_EXPR.
	(c_fully_fold_internal): Disallow EXCESS_PRECISION_EXPR.
	* c-common.def (EXCESS_PRECISION_EXPR): New.
	* c-cppbuiltin.c (builtin_define_float_constants): Define
	constants with enough digits for long double.
	* c-lex.c (interpret_float): Interpret constant with excess
	precision where appropriate.
	* c-opts.c (c_common_post_options): Set
	flag_excess_precision_cmdline.  Give an error for
	-fexcess-precision=standard for C++ for processors where the
	option is significant.
	* c-parser.c (c_parser_conditional_expression): Handle excess
	precision in condition.
	* c-typeck.c (convert_arguments): Handle arguments with excess
	precision.
	(build_unary_op): Move excess precision outside operation.
	(build_conditional_expr): Likewise.
	(build_compound_expr): Likewise.
	(build_c_cast): Do cast on operand of EXCESS_PRECISION_EXPR.
	(build_modify_expr): Handle excess precision in RHS.
	(convert_for_assignment): Handle excess precision in converted
	value.
	(digest_init, output_init_element, process_init_element): Handle
	excess precision in initializer.
	(c_finish_return): Handle excess precision in return value.
	(build_binary_op): Handle excess precision in operands and add
	excess precision as needed for operation.
	* common.opt (-fexcess-precision=): New option.
	* config/i386/i386.h (X87_ENABLE_ARITH, X87_ENABLE_FLOAT): New.
	* config/i386/i386.md (float<SSEMODEI24:mode><X87MODEF:mode>2):
	For standard excess precision, output explicit conversion to and
	truncation from XFmode.
	(*float<SSEMODEI24:mode><X87MODEF:mode>2_1,
	*float<SSEMODEI24:mode><X87MODEF:mode>2_i387_with_temp,
	*float<SSEMODEI24:mode><X87MODEF:mode>2_i387, two unnamed
	define_splits, floatdi<X87MODEF:mode>2_i387_with_xmm, two unnamed
	define_splits, *floatunssi<mode>2_1, two unnamed define_splits,
	floatunssi<mode>2, add<mode>3, sub<mode>3, mul<mode>3, divdf3,
	divsf3, *fop_<mode>_comm_i387, *fop_<mode>_1_i387,
	*fop_<MODEF:mode>_2_i387, *fop_<MODEF:mode>_3_i387,
	*fop_df_4_i387, *fop_df_5_i387, *fop_df_6_i387, two unnamed
	define_splits, sqrt<mode>2): Disable where appropriate for
	standard excess precision.
	* convert.c (convert_to_real): Do not shorten arithmetic to type
	for which excess precision would be used.
	* defaults.h (TARGET_FLT_EVAL_METHOD_NON_DEFAULT): Define.
	* doc/invoke.texi (-fexcess-precision=): Document option.
	(-mfpmath=): Correct index entry.
	* flags.h (enum excess_precision, flag_excess_precision_cmdline,
	flag_excess_precision): New.
	* langhooks.c (lhd_post_options): Set
	flag_excess_precision_cmdline.
	* opts.c (common_handle_option): Handle -fexcess-precision=.
	* toplev.c (flag_excess_precision_cmdline, flag_excess_precision,
	init_excess_precision): New.
	(lang_dependent_init_target): Call init_excess_precision.
	* tree.c (excess_precision_type): New.
	* tree.h (excess_precision_type): Declare.

ada:
	* gcc-interface/misc.c (gnat_post_options): Set
	flag_excess_precision_cmdline.  Give an error for
	-fexcess-precision=standard for processors where the option is
	significant.

fortran:
	* options.c (gfc_post_options): Set
	flag_excess_precision_cmdline.  Give an error for
	-fexcess-precision=standard for processors where the option is
	significant.

java:
	* lang.c (java_post_options): Set flag_excess_precision_cmdline.
	Give an error for -fexcess-precision=standard for processors where
	the option is significant.

testsuite:
	* gcc.target/i386/excess-precision-1.c,
	gcc.target/i386/excess-precision-2.c,
	gcc.target/i386/excess-precision-3.c,
	gcc.target/i386/excess-precision-4.c,
	gcc.target/i386/excess-precision-5.c,
	gcc.target/i386/excess-precision-6.c: New tests.

From-SVN: r145272

1 files changed, 24 insertions, 5 deletions

diff --git a/gcc/c-lex.c b/gcc/c-lex.c
index 5b71c3b..72a9590 100644
--- a/gcc/c-lex.c
+++ b/gcc/c-lex.c
@@ -605,8 +605,10 @@ static tree
 interpret_float (const cpp_token *token, unsigned int flags)
 {
   tree type;
+  tree const_type;
   tree value;
   REAL_VALUE_TYPE real;
+  REAL_VALUE_TYPE real_trunc;
   char *copy;
   size_t copylen;
 
@@ -655,6 +657,10 @@ interpret_float (const cpp_token *token, unsigned int flags)
     else
       type = double_type_node;
 
+  const_type = excess_precision_type (type);
+  if (!const_type)
+    const_type = type;
+
   /* Copy the constant to a nul-terminated buffer.  If the constant
      has any suffixes, cut them off; REAL_VALUE_ATOF/ REAL_VALUE_HTOF
      can't handle them.  */
@@ -675,13 +681,21 @@ interpret_float (const cpp_token *token, unsigned int flags)
   memcpy (copy, token->val.str.text, copylen);
   copy[copylen] = '\0';
 
-  real_from_string3 (&real, copy, TYPE_MODE (type));
+  real_from_string3 (&real, copy, TYPE_MODE (const_type));
+  if (const_type != type)
+    /* Diagnosing if the result of converting the value with excess
+       precision to the semantic type would overflow (with associated
+       double rounding) is more appropriate than diagnosing if the
+       result of converting the string directly to the semantic type
+       would overflow.  */
+    real_convert (&real_trunc, TYPE_MODE (type), &real);
 
   /* Both C and C++ require a diagnostic for a floating constant
      outside the range of representable values of its type.  Since we
      have __builtin_inf* to produce an infinity, this is now a
      mandatory pedwarn if the target does not support infinities.  */
-  if (REAL_VALUE_ISINF (real)) 
+  if (REAL_VALUE_ISINF (real)
+      || (const_type != type && REAL_VALUE_ISINF (real_trunc)))
     {
       if (!MODE_HAS_INFINITIES (TYPE_MODE (type)))
 	pedwarn (input_location, 0, "floating constant exceeds range of %qT", type);
@@ -689,7 +703,8 @@ interpret_float (const cpp_token *token, unsigned int flags)
 	warning (OPT_Woverflow, "floating constant exceeds range of %qT", type);
     }
   /* We also give a warning if the value underflows.  */
-  else if (REAL_VALUES_EQUAL (real, dconst0))
+  else if (REAL_VALUES_EQUAL (real, dconst0)
+	   || (const_type != type && REAL_VALUES_EQUAL (real_trunc, dconst0)))
     {
       REAL_VALUE_TYPE realvoidmode;
       int overflow = real_from_string (&realvoidmode, copy);
@@ -698,9 +713,13 @@ interpret_float (const cpp_token *token, unsigned int flags)
     }
 
   /* Create a node with determined type and value.  */
-  value = build_real (type, real);
+  value = build_real (const_type, real);
   if (flags & CPP_N_IMAGINARY)
-    value = build_complex (NULL_TREE, convert (type, integer_zero_node), value);
+    value = build_complex (NULL_TREE, convert (const_type, integer_zero_node),
+			   value);
+
+  if (type != const_type)
+    value = build1 (EXCESS_PRECISION_EXPR, type, value);
 
   return value;
 }