* emit-rtl.c (static_regno_reg_rtx): Define.

        (init_emit_once): Initialize static_regno_reg_rtx.
        (init_emit): Copy static_regno_reg_rtx into regno_reg_rtx instead
        of building new hard reg objects once per function.
        (gen_rtx_REG): Try to share hard regs.
	* regclass.c (init_fake_stack_mems): New function broken out from
	init_regs.
	* rtl.h (init_fake_stack_mems): Declare.
	* toplev.c (lang_independent_init): Call init_regs before
	init_emit_once.  Call init_fake_stack_mems after init_emit_once.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@54588 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 23 insertions, 4 deletions

diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 27a511f0331..5186c854dc3 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -92,6 +92,12 @@ static int no_line_numbers;
 
 rtx global_rtl[GR_MAX];
 
+/* Commonly used RTL for hard registers.  These objects are not necessarily
+   unique, so we allocate them separately from global_rtl.  They are
+   initialized once per compilation unit, then copied into regno_reg_rtx
+   at the beginning of each function.  */
+static GTY(()) rtx static_regno_reg_rtx[FIRST_PSEUDO_REGISTER];
+
 /* We record floating-point CONST_DOUBLEs in each floating-point mode for
    the values of 0, 1, and 2.  For the integer entries and VOIDmode, we
    record a copy of const[012]_rtx.  */
@@ -527,6 +533,15 @@ gen_rtx_REG (mode, regno)
 	return stack_pointer_rtx;
     }
 
+  /* If the per-function register table has been set up, try to re-use
+     an existing entry in that table to avoid useless generation of RTL.  */
+  if (cfun
+      && cfun->emit
+      && regno_reg_rtx
+      && regno < FIRST_PSEUDO_REGISTER
+      && reg_raw_mode[regno] == mode)
+    return regno_reg_rtx[regno];
+
   return gen_raw_REG (mode, regno);
 }
 
@@ -5067,7 +5082,6 @@ void
 init_emit ()
 {
   struct function *f = cfun;
-  int i;
 
   f->emit = (struct emit_status *) ggc_alloc (sizeof (struct emit_status));
   first_insn = NULL;
@@ -5098,13 +5112,13 @@ init_emit ()
 				  * sizeof (tree));
 
   /* Put copies of all the hard registers into regno_reg_rtx.  */
-  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
-    regno_reg_rtx[i] = gen_raw_REG (reg_raw_mode[i], i);
+  memcpy (regno_reg_rtx,
+	  static_regno_reg_rtx,
+	  FIRST_PSEUDO_REGISTER * sizeof (rtx));
 
   /* Put copies of all the virtual register rtx into regno_reg_rtx.  */
   init_virtual_regs (f->emit);
 
-
   /* Indicate that the virtual registers and stack locations are
      all pointers.  */
   REG_POINTER (stack_pointer_rtx) = 1;
@@ -5238,6 +5252,11 @@ init_emit_once (line_numbers)
     gen_raw_REG (Pmode, VIRTUAL_OUTGOING_ARGS_REGNUM);
   virtual_cfa_rtx = gen_raw_REG (Pmode, VIRTUAL_CFA_REGNUM);
 
+  /* Initialize RTL for commonly used hard registers.  These are
+     copied into regno_reg_rtx as we begin to compile each function.  */
+  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
+    static_regno_reg_rtx[i] = gen_raw_REG (reg_raw_mode[i], i);
+
 #ifdef INIT_EXPANDERS
   /* This is to initialize {init|mark|free}_machine_status before the first
      call to push_function_context_to.  This is needed by the Chill front