PATCH: handle decimal float modes on ia32/x86-64

[Ben Elliston <bje at au1 dot ibm dot com>]

This patch adds ia32 and x86-64 backend support for the decimal float
modes.  The x86-64 patch conforms to the recent additions to the
x86-64 ABI for decimal floating point types, passing via SSE
registers.

These changes have been tested with the requisite t-* Makefile changes
to activate them, but I am not submitting those here.  Tested with a
bootstrap and regression test run on i686-pc-linux-gnu and
x64_64-unknown-linux-gnu.

The change to i386.h is required for the dfp runtime routines.

Okay for the trunk?
Ben

2006-02-01  Ben Elliston  <bje@au.ibm.com>

	* config/i386/i386.h (LIBGCC2_WORDS_BIG_ENDIAN): Define.
	* config/i386/i386.c (ix86_scalar_mode_supported_p): New.
	(TARGET_SCALAR_MODE_SUPPORTED_P): Define hook.
	(classify_argument): Handle SDmode, DDmode, TDmode.
	(ix86_return_in_memory): Handle TDmode.
	(ix86_libcall_value): Handle SDmode, DDmode, TDmode.
	(ix86_value_regno): Return non-TDmode decimal float modes in %eax.

Index: i386.h
===================================================================
--- i386.h	(revision 110412)
+++ i386.h	(working copy)
@@ -536,6 +536,9 @@ extern int x86_prefetch_sse;
    numbered.  */
 /* Not true for 80386 */
 #define WORDS_BIG_ENDIAN 0
+#ifdef IN_LIBGCC2
+#define LIBGCC2_WORDS_BIG_ENDIAN 0
+#endif /* IN_LIBGCC2 */
 
 /* Width of a word, in units (bytes).  */
 #define UNITS_PER_WORD (TARGET_64BIT ? 8 : 4)
Index: i386.c
===================================================================
--- i386.c	(revision 110412)
+++ i386.c	(working copy)
@@ -1095,6 +1095,7 @@ static tree ix86_build_builtin_va_list (
 static void ix86_setup_incoming_varargs (CUMULATIVE_ARGS *, enum machine_mode,
 					 tree, int *, int);
 static tree ix86_gimplify_va_arg (tree, tree, tree *, tree *);
+static bool ix86_scalar_mode_supported_p (enum machine_mode);
 static bool ix86_vector_mode_supported_p (enum machine_mode);
 
 static int ix86_address_cost (rtx);
@@ -1320,6 +1321,9 @@ static section *x86_64_elf_select_sectio
 #undef TARGET_GIMPLIFY_VA_ARG_EXPR
 #define TARGET_GIMPLIFY_VA_ARG_EXPR ix86_gimplify_va_arg
 
+#undef TARGET_SCALAR_MODE_SUPPORTED_P
+#define TARGET_SCALAR_MODE_SUPPORTED_P ix86_scalar_mode_supported_p
+
 #undef TARGET_VECTOR_MODE_SUPPORTED_P
 #define TARGET_VECTOR_MODE_SUPPORTED_P ix86_vector_mode_supported_p
 
@@ -3053,6 +3057,14 @@ classify_argument (enum machine_mode mod
   /* Classification of atomic types.  */
   switch (mode)
     {
+    case SDmode:
+    case DDmode:
+      classes[0] = X86_64_SSE_CLASS;
+      return 1;
+    case TDmode:
+      classes[0] = X86_64_SSE_CLASS;
+      classes[1] = X86_64_SSEUP_CLASS;
+      return 2;
     case DImode:
     case SImode:
     case HImode:
@@ -3796,6 +3808,9 @@ ix86_return_in_memory (tree type)
   if (mode == XFmode)
     return 0;
 
+  if (mode == TDmode)
+    return 1;
+
   if (size > 12)
     return 1;
   return 0;
@@ -3861,6 +3876,9 @@ ix86_libcall_value (enum machine_mode mo
 	case DFmode:
 	case DCmode:
 	case TFmode:
+	case SDmode:
+	case DDmode:
+	case TDmode:
 	  return gen_rtx_REG (mode, FIRST_SSE_REG);
 	case XFmode:
 	case XCmode:
@@ -3892,6 +3910,10 @@ ix86_value_regno (enum machine_mode mode
   if (mode == TImode || (VECTOR_MODE_P (mode) && GET_MODE_SIZE (mode) == 16))
     return FIRST_SSE_REG;
 
+  /* Decimal floating point values can go in %eax, unlike other float modes.  */
+  if (DECIMAL_FLOAT_MODE_P (mode))
+    return 0;
+
   /* Most things go in %eax, except (unless -mno-fp-ret-in-387) fp values.  */
   if (!SCALAR_FLOAT_MODE_P (mode) || !TARGET_FLOAT_RETURNS_IN_80387)
     return 0;
@@ -18303,6 +18325,16 @@ ix86_expand_reduc_v4sf (rtx (*fn) (rtx, 
   emit_insn (fn (dest, tmp2, tmp3));
 }
 
+/* Target hook for scalar_mode_supported_p.  */
+static bool
+ix86_scalar_mode_supported_p (enum machine_mode mode)
+{
+  if (DECIMAL_FLOAT_MODE_P (mode))
+    return true;
+  else
+    return default_scalar_mode_supported_p (mode);
+}
+
 /* Implements target hook vector_mode_supported_p.  */
 static bool
 ix86_vector_mode_supported_p (enum machine_mode mode)