invoke.texi: Document -frename-registers.

        * invoke.texi: Document -frename-registers.  Add it to -O3.
        * toplev.c (rest_of_compilation): Run regrename before ifcvt2.
        (enum dump_file_index, dump_file): Update order.
        (main): Set flag_rename_registers at -O3.

From-SVN: r37092

gcc/ChangeLog

 2000-10-27  Richard Henderson  <rth@redhat.com>
 
+	* invoke.texi: Document -frename-registers.  Add it to -O3.
+	* toplev.c (rest_of_compilation): Run regrename before ifcvt2.
+	(enum dump_file_index, dump_file): Update order.
+	(main): Set flag_rename_registers at -O3.
+
+2000-10-27  Richard Henderson  <rth@redhat.com>
+
 	* config/alpha/alpha.h (enum reg_class): Add PV_REG.
 	(REG_CLASS_NAMES, REG_CLASS_CONTENTS, REGNO_REG_CLASS): Update.
 	(REG_CLASS_FROM_LETTER): Assign it to 'c'.

gcc/invoke.texi

@@ -175,9 +175,9 @@ in the following sections.
 -fmove-all-movables  -fno-default-inline  -fno-defer-pop
 -fno-function-cse  -fno-inline  -fno-peephole -ftrapv
 -fomit-frame-pointer  -foptimize-register-moves -foptimize-sibling-calls
--fregmove -frerun-cse-after-loop  -frerun-loop-opt  -freduce-all-givs
--fschedule-insns  -fschedule-insns2  -fssa -fstrength-reduce
--fstrict-aliasing  -fthread-jumps  -funroll-all-loops
+-fregmove  -frename-registers  -frerun-cse-after-loop  -frerun-loop-opt
+-freduce-all-givs  -fschedule-insns  -fschedule-insns2  -fssa
+-fstrength-reduce  -fstrict-aliasing  -fthread-jumps  -funroll-all-loops
 -funroll-loops 
 -O  -O0  -O1  -O2  -O3 -Os
 @end smallexample
@@ -2577,14 +2577,15 @@ perform loop unrolling or function inlining when you specify @samp{-O2}.
 As compared to @samp{-O}, this option increases both compilation time
 and the performance of the generated code.
 
-@samp{-O2} turns on all optional optimizations except for loop unrolling
-and function inlining.  It also turns on the @samp{-fforce-mem} option
-on all machines and frame pointer elimination on machines where doing so
-does not interfere with debugging.
+@samp{-O2} turns on all optional optimizations except for loop unrolling,
+function inlining, and register renaming.  It also turns on the
+@samp{-fforce-mem} option on all machines and frame pointer elimination
+on machines where doing so does not interfere with debugging.
 
 @item -O3
 Optimize yet more.  @samp{-O3} turns on all optimizations specified by
-@samp{-O2} and also turns on the @samp{inline-functions} option.
+@samp{-O2} and also turns on the @samp{-finline-functions} and
+@samp{-frename-registers} options.
 
 @item -O0
 Do not optimize.
@@ -2805,7 +2806,6 @@ halting the program may not work properly with this option.  Use
 -fno-delete-null-pointer-checks to disable this optimizing for programs
 which depend on that behavior.
 
-
 @item -fexpensive-optimizations
 Perform a number of minor optimizations that are relatively expensive.
 
@@ -3033,6 +3033,12 @@ Perform dead-code elimination in SSA form.  Requires @samp{-fssa}.  Like
 Treat floating point constant as single precision constant instead of
 implicitly converting it to double precision constant.
 
+@item -frename-registers
+Attempt to avoid false dependancies in scheduled code by making use
+of registers left over after register allocation.  This optimization
+will most benefit processors with lots of registers.  It can, however,
+make debugging impossible, since variables will no longer stay in
+a ``home register''.
 @end table
 
 @node Preprocessor Options

gcc/toplev.c

@@ -277,9 +277,9 @@ enum dump_file_index
   DFI_lreg,
   DFI_greg,
   DFI_flow2,
-  DFI_ce2,
   DFI_peephole2,
   DFI_rnreg,
+  DFI_ce2,
   DFI_sched2,
   DFI_bbro,
   DFI_jump2,
@@ -321,9 +321,9 @@ struct dump_file_info dump_file[DFI_MAX] =
   { "lreg",	'l', 1, 0, 0 },
   { "greg",	'g', 1, 0, 0 },
   { "flow2",	'w', 1, 0, 0 },
-  { "ce2",	'E', 1, 0, 0 },
   { "peephole2", 'z', 1, 0, 0 },
   { "rnreg",	'n', 1, 0, 0 },
+  { "ce2",	'E', 1, 0, 0 },
   { "sched2",	'R', 1, 0, 0 },
   { "bbro",	'B', 1, 0, 0 },
   { "jump2",	'J', 1, 0, 0 },
@@ -3509,17 +3509,6 @@ rest_of_compilation (decl)
   close_dump_file (DFI_flow2, print_rtl_with_bb, insns);
   timevar_pop (TV_FLOW2);
 
-  if (optimize > 0)
-    {
-      timevar_push (TV_IFCVT2);
-      open_dump_file (DFI_ce2, decl);
-
-      if_convert (1);
-
-      close_dump_file (DFI_ce2, print_rtl_with_bb, insns);
-      timevar_pop (TV_IFCVT2);
-    }
-
 #ifdef HAVE_peephole2
   if (optimize > 0 && flag_peephole2)
     {
@@ -3544,6 +3533,17 @@ rest_of_compilation (decl)
       timevar_pop (TV_RENAME_REGISTERS);
     }
 
+  if (optimize > 0)
+    {
+      timevar_push (TV_IFCVT2);
+      open_dump_file (DFI_ce2, decl);
+
+      if_convert (1);
+
+      close_dump_file (DFI_ce2, print_rtl_with_bb, insns);
+      timevar_pop (TV_IFCVT2);
+    }
+
 #ifdef INSN_SCHEDULING
   if (optimize > 0 && flag_schedule_insns_after_reload)
     {
@@ -4633,6 +4633,7 @@ main (argc, argv)
   if (optimize >= 3)
     {
       flag_inline_functions = 1;
+      flag_rename_registers = 1;
     }
 
   if (optimize < 2 || optimize_size)