sparc.h: Rework comments about the code model in 64-bit environment and the mode 'Pmode'.

	* config/sparc/sparc.h: Rework comments about the code model
	in 64-bit environment and the mode 'Pmode'.
	* doc/invoke.texi (SPARC options): Rework description of the
	different code models supported in 64-bit environment.

From-SVN: r79509

gcc/ChangeLog

+2004-03-15  Eric Botcazou  <ebotcazou@act-europe.fr>
+
+	* config/sparc/sparc.h: Rework comments about the code model
+	in 64-bit environment and the mode 'Pmode'.
+	* doc/invoke.texi (SPARC options): Rework description of the
+	different code models supported in 64-bit environment.
+
 2004-03-15  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* defaults.h (REVERSIBLE_CC_MODE): Define.

gcc/config/sparc/sparc.h

@@ -69,35 +69,41 @@ Boston, MA 02111-1307, USA.  */
 #endif /* IN_LIBGCC2 */
 #define TARGET_ARCH64 (! TARGET_ARCH32)
 
-/* Code model selection.
-   -mcmodel is used to select the v9 code model.
-   Different code models aren't supported for v7/8 code.
-
-   TARGET_CM_32:     32 bit address space, top 32 bits = 0,
-		     pointers are 32 bits.  Note that this isn't intended
-                     to imply a v7/8 abi.
-
-   TARGET_CM_MEDLOW: 32 bit address space, top 32 bits = 0,
-                     avoid generating %uhi and %ulo terms,
-		     pointers are 64 bits.
-
-   TARGET_CM_MEDMID: 64 bit address space.
-                     The executable must be in the low 16 TB of memory.
-                     This corresponds to the low 44 bits, and the %[hml]44
-                     relocs are used.  The text segment has a maximum size
-                     of 31 bits.
-
-   TARGET_CM_MEDANY: 64 bit address space.
-                     The text and data segments have a maximum size of 31
-                     bits and may be located anywhere.  The maximum offset
-                     from any instruction to the label _GLOBAL_OFFSET_TABLE_
-                     is 31 bits.
-
-   TARGET_CM_EMBMEDANY: 64 bit address space.
-                     The text and data segments have a maximum size of 31 bits
-                     and may be located anywhere.  Register %g4 contains
-                     the start address of the data segment.
-*/
+/* Code model selection in 64-bit environment.
+
+   The machine mode used for addresses is 32-bit wide:
+
+   TARGET_CM_32:     32-bit address space.
+                     It is the code model used when generating 32-bit code.
+
+   The machine mode used for addresses is 64-bit wide:
+
+   TARGET_CM_MEDLOW: 32-bit address space.
+                     The executable must be in the low 32 bits of memory.
+                     This avoids generating %uhi and %ulo terms.  Programs
+                     can be statically or dynamically linked.
+
+   TARGET_CM_MEDMID: 44-bit address space.
+                     The executable must be in the low 44 bits of memory,
+                     and the %[hml]44 terms are used.  The text and data
+                     segments have a maximum size of 2GB (31-bit span).
+                     The maximum offset from any instruction to the label
+                     _GLOBAL_OFFSET_TABLE_ is 2GB (31-bit span).
+
+   TARGET_CM_MEDANY: 64-bit address space.
+                     The text and data segments have a maximum size of 2GB
+                     (31-bit span) and may be located anywhere in memory.
+                     The maximum offset from any instruction to the label
+                     _GLOBAL_OFFSET_TABLE_ is 2GB (31-bit span).
+
+   TARGET_CM_EMBMEDANY: 64-bit address space.
+                     The text and data segments have a maximum size of 2GB
+                     (31-bit span) and may be located anywhere in memory.
+                     The global register %g4 contains the start address of
+                     the data segment.  Programs are statically linked and
+                     PIC is not supported.
+
+   Different code models are not supported in 32-bit environment.  */
 
 enum cmodel {
   CM_32,
@@ -2212,9 +2218,7 @@ do {                                                                    \
    is done just by pretending it is already truncated.  */
 #define TRULY_NOOP_TRUNCATION(OUTPREC, INPREC) 1
 
-/* Specify the machine mode that pointers have.
-   After generation of rtl, the compiler makes no further distinction
-   between pointers and any other objects of this machine mode.  */
+/* Specify the machine mode used for addresses.  */
 #define Pmode (TARGET_ARCH64 ? DImode : SImode)
 
 /* Generate calls to memcpy, memcmp and memset.  */

gcc/doc/invoke.texi

@@ -6360,31 +6360,31 @@ to 64 bits.
 
 @item -mcmodel=medlow
 @opindex mcmodel=medlow
-Generate code for the Medium/Low code model: the program must be linked
-in the low 32 bits of the address space.  Pointers are 64 bits.
-Programs can be statically or dynamically linked.
+Generate code for the Medium/Low code model: 64-bit addresses, programs
+must be linked in the low 32 bits of memory.  Programs can be statically
+or dynamically linked.
 
 @item -mcmodel=medmid
 @opindex mcmodel=medmid
-Generate code for the Medium/Middle code model: the program must be linked
-in the low 44 bits of the address space, the text segment must be less than
-2G bytes, and data segment must be within 2G of the text segment.
-Pointers are 64 bits.
+Generate code for the Medium/Middle code model: 64-bit addresses, programs
+must be linked in the low 44 bits of memory, the text and data segments must
+be less than 2GB in size and the data segment must be located within 2GB of
+the text segment.
 
 @item -mcmodel=medany
 @opindex mcmodel=medany
-Generate code for the Medium/Anywhere code model: the program may be linked
-anywhere in the address space, the text segment must be less than
-2G bytes, and data segment must be within 2G of the text segment.
-Pointers are 64 bits.
+Generate code for the Medium/Anywhere code model: 64-bit addresses, programs
+may be linked anywhere in memory, the text and data segments must be less
+than 2GB in size and the data segment must be located within 2GB of the
+text segment.
 
 @item -mcmodel=embmedany
 @opindex mcmodel=embmedany
 Generate code for the Medium/Anywhere code model for embedded systems:
-assume a 32-bit text and a 32-bit data segment, both starting anywhere
-(determined at link time).  Register %g4 points to the base of the
-data segment.  Pointers are still 64 bits.
-Programs are statically linked, PIC is not supported.
+64-bit addresses, the text and data segments must be less than 2GB in
+size, both starting anywhere in memory (determined at link time).  The
+global register %g4 points to the base of the data segment.  Programs
+are statically linked and PIC is not supported.
 
 @item -mstack-bias
 @itemx -mno-stack-bias