[committed] VAX: Implement the `-mlra' command-line option

["Maciej W. Rozycki" <macro@embecosm.com>]

Add the the `-mlra' command-line option for the VAX target, with the 
usual semantics of enabling Local Register Allocation, off by default.

LRA remains unstable with the VAX target, with numerous ICEs throughout 
the testsuite and worse code produced overall where successful, however 
the presence of a command line option to enable it makes it easier to 
experiment with it as the compiler does not have to be rebuilt to flip 
between the old reload and LRA.

	gcc/
	* config/vax/vax.c (vax_lra_p): New prototype and function.
	(TARGET_LRA_P): Wire it.
	* config/vax/vax.opt (mlra): New option.
	* doc/invoke.texi (Option Summary, VAX Options): Document the 
	new option.
---
 gcc/config/vax/vax.c   |   11 ++++++++++-
 gcc/config/vax/vax.opt |    4 ++++
 gcc/doc/invoke.texi    |    9 ++++++++-
 3 files changed, 22 insertions(+), 2 deletions(-)

gcc-vax-mlra.diff
Index: gcc/gcc/config/vax/vax.c
===================================================================
--- gcc.orig/gcc/config/vax/vax.c
+++ gcc/gcc/config/vax/vax.c
@@ -62,6 +62,7 @@ static rtx vax_function_arg (cumulative_
 static void vax_function_arg_advance (cumulative_args_t,
 				      const function_arg_info &);
 static rtx vax_struct_value_rtx (tree, int);
+static bool vax_lra_p (void);
 static void vax_asm_trampoline_template (FILE *);
 static void vax_trampoline_init (rtx, tree, rtx);
 static poly_int64 vax_return_pops_args (tree, tree, poly_int64);
@@ -114,7 +115,7 @@ static HOST_WIDE_INT vax_starting_frame_
 #define TARGET_STRUCT_VALUE_RTX vax_struct_value_rtx
 
 #undef TARGET_LRA_P
-#define TARGET_LRA_P hook_bool_void_false
+#define TARGET_LRA_P vax_lra_p
 
 #undef TARGET_LEGITIMATE_ADDRESS_P
 #define TARGET_LEGITIMATE_ADDRESS_P vax_legitimate_address_p
@@ -1221,6 +1222,14 @@ vax_struct_value_rtx (tree fntype ATTRIB
   return gen_rtx_REG (Pmode, VAX_STRUCT_VALUE_REGNUM);
 }
 
+/* Return true if we use LRA instead of reload pass.  */
+
+static bool
+vax_lra_p (void)
+{
+  return TARGET_LRA;
+}
+
 /* Output integer move instructions.  */
 
 bool
Index: gcc/gcc/config/vax/vax.opt
===================================================================
--- gcc.orig/gcc/config/vax/vax.opt
+++ gcc/gcc/config/vax/vax.opt
@@ -42,6 +42,10 @@ munix
 Target RejectNegative Mask(UNIX_ASM)
 Generate code for UNIX assembler.
 
+mlra
+Target Mask(LRA)
+Enable Local Register Allocation.
+
 mvaxc-alignment
 Target RejectNegative Mask(VAXC_ALIGNMENT)
 Use VAXC structure conventions.
Index: gcc/gcc/doc/invoke.texi
===================================================================
--- gcc.orig/gcc/doc/invoke.texi
+++ gcc/gcc/doc/invoke.texi
@@ -1364,7 +1364,7 @@ See RS/6000 and PowerPC Options.
 -mbig-switch}
 
 @emph{VAX Options}
-@gccoptlist{-mg  -mgnu  -munix}
+@gccoptlist{-mg  -mgnu  -munix  -mlra}
 
 @emph{Visium Options}
 @gccoptlist{-mdebug  -msim  -mfpu  -mno-fpu  -mhard-float  -msoft-float @gol
@@ -30523,6 +30523,13 @@ GNU assembler is being used.
 @item -mg
 @opindex mg
 Output code for G-format floating-point numbers instead of D-format.
+
+@item -mlra
+@itemx -mno-lra
+@opindex mlra
+@opindex mno-lra
+Enable Local Register Allocation.  This is still experimental for the VAX,
+so by default the compiler uses standard reload.
 @end table
 
 @node Visium Options