stor-layout.c (layout_type): Use FORCE_STRUCT_BLK.

	* stor-layout.c (layout_type): Use FORCE_STRUCT_BLK.
	* tm.texi (FORCE_STRUCT_BLK): Document.
	* config/c4x/c4x.h (FORCE_STRUCT_BLK): New macro.

From-SVN: r31385

gcc/ChangeLog

+2000-01-13  Michael Hayes  <m.hayes@elec.canterbury.ac.nz>
+
+	* stor-layout.c (layout_type): Use FORCE_STRUCT_BLK.
+	* tm.texi (FORCE_STRUCT_BLK): Document.
+	* config/c4x/c4x.h (FORCE_STRUCT_BLK): New macro.
+
 Wed Jan 12 23:12:47 2000  Hans-Peter Nilsson  <hp@axis.com>
 
 	* config/ns32k/ns32k.md: Revert Jan 9 change.

gcc/config/c4x/c4x.h

@@ -352,6 +352,10 @@ extern const char *c4x_rpts_cycles_string, *c4x_cpu_version_string;
 #define TARGET_FLOAT_FORMAT	C4X_FLOAT_FORMAT
 #define MAX_FIXED_MODE_SIZE	64 /* HImode.  */
 
+/* If a structure has a floating point field then force structure
+   to have BLKMODE.  */
+#define STRUCT_FORCE_BLK(FIELD) (TREE_CODE (TREE_TYPE (FIELD)) == REAL_TYPE)
+
 /* Number of bits in the high and low parts of a two stage
    load of an immediate constant.  */
 #define BITS_PER_HIGH 16

gcc/stor-layout.c

@@ -1057,6 +1057,13 @@ layout_type (type)
 		 register instead of forcing it to live in the stack.  */
 	      if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
 		mode = DECL_MODE (field);
+
+#ifdef STRUCT_FORCE_BLK
+	      /* With some targets, eg. c4x, it is sub-optimal
+		 to access an aligned BLKmode structure as a scalar.  */
+	      if (mode == VOIDmode && STRUCT_FORCE_BLK (field))
+		  goto record_lose;
+#endif /* STRUCT_FORCE_BLK  */
 	    }
 
 	  if (mode != VOIDmode)

gcc/tm.texi

@@ -413,6 +413,15 @@ if any, in all upper-case letters.  For example, it might be @samp{GCC}
 or @samp{BINUTILS}.  If the package is part of the a vendor-supplied
 operating system, code the component name as @samp{0}.
 
+@findex STRUCT_FORCE_BLK
+@item STRUCT_FORCE_BLK (@var{field})
+Return 1 if a structure containing @var{field} should be accessed using
+@code{BLKMODE}.
+
+Normally, this is not needed.  See the file @file{c4x.h} for an example
+of how to use this macro to prevent a structure having a floating point
+field from being accessed in an integer mode.
+
 
 For example, here is the definition used for VAX/VMS: