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.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@145272 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 45 insertions, 0 deletions

diff --git a/gcc/toplev.c b/gcc/toplev.c
index 8417cfed6cb..72f3d3087d3 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -281,6 +281,11 @@ enum ira_region flag_ira_region = IRA_REGION_MIXED;
 
 unsigned int flag_ira_verbose = 5;
 
+/* Set the default for excess precision.  */
+
+enum excess_precision flag_excess_precision_cmdline = EXCESS_PRECISION_DEFAULT;
+enum excess_precision flag_excess_precision = EXCESS_PRECISION_DEFAULT;
+
 /* Nonzero means change certain warnings into errors.
    Usually these are warnings about failure to conform to some standard.  */
 
@@ -2033,11 +2038,51 @@ backend_init (void)
   backend_init_target ();
 }
 
+/* Initialize excess precision settings.  */
+static void
+init_excess_precision (void)
+{
+  /* Adjust excess precision handling based on the target options.  If
+     the front end cannot handle it, flag_excess_precision_cmdline
+     will already have been set accordingly in the post_options
+     hook.  */
+  gcc_assert (flag_excess_precision_cmdline != EXCESS_PRECISION_DEFAULT);
+  flag_excess_precision = flag_excess_precision_cmdline;
+  if (flag_unsafe_math_optimizations)
+    flag_excess_precision = EXCESS_PRECISION_FAST;
+  if (flag_excess_precision == EXCESS_PRECISION_STANDARD)
+    {
+      int flt_eval_method = TARGET_FLT_EVAL_METHOD;
+      switch (flt_eval_method)
+	{
+	case -1:
+	case 0:
+	  /* Either the target acts unpredictably (-1) or has all the
+	     operations required not to have excess precision (0).  */
+	  flag_excess_precision = EXCESS_PRECISION_FAST;
+	  break;
+	case 1:
+	case 2:
+	  /* In these cases, predictable excess precision makes
+	     sense.  */
+	  break;
+	default:
+	  /* Any other implementation-defined FLT_EVAL_METHOD values
+	     require the compiler to handle the associated excess
+	     precision rules in excess_precision_type.  */
+	  gcc_unreachable ();
+	}
+    }
+}
+
 /* Initialize things that are both lang-dependent and target-dependent.
    This function can be called more than once if target parameters change.  */
 static void
 lang_dependent_init_target (void)
 {
+  /* This determines excess precision settings.  */
+  init_excess_precision ();
+
   /* This creates various _DECL nodes, so needs to be called after the
      front end is initialized.  It also depends on the HAVE_xxx macros
      generated from the target machine description.  */