[PATCH 1/3] SH-2A FDPIC: New pattern: use_initial_val

[Andrew Stubbs <ams at codesourcery dot com>]

This patch creates a new instruction pattern "use_initial_val".

The purpose of this patch is to allow late optimization passes to use 
re-use existing pseudo-registers, even if the use of the register has 
been optimized away in earlier passes.

This feature is required by our SH-2A FDPIC (to follow), but has been 
split out here because it is target independent.

OK to commit?

Andrew Stubbs
2010-08-19  Bernd Schmidt  <bernds@codesourcery.com>

	gcc/
	* Makefile.in: (mode-switching.o): Depend on integrate.h.
	* doc/md.texi (Standard Pattern Names For Generation):
	Document use_initial_val.
	* integrate.c (initial_value_pair): Add new member "initialized".
	(get_hard_reg_initial_val): Set initialized.
	(emit_initial_value_sets): Emit result of gen_use_initial_val.
	* mode-switching.c: Include integrate.h.
	(rest_of_handle_mode_switching): Call emit_initial_value_sets.

---
 src/gcc-mainline/gcc/Makefile.in      |    3 ++-
 src/gcc-mainline/gcc/doc/md.texi      |    7 +++++++
 src/gcc-mainline/gcc/integrate.c      |   23 ++++++++++++++++++-----
 src/gcc-mainline/gcc/mode-switching.c |    2 ++
 4 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/src/gcc-mainline/gcc/Makefile.in b/src/gcc-mainline/gcc/Makefile.in
index 49b0634..4c035a7 100644
--- a/src/gcc-mainline/gcc/Makefile.in
+++ b/src/gcc-mainline/gcc/Makefile.in
@@ -3119,7 +3119,8 @@ lcm.o : lcm.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) $(REGS_H) \
 mode-switching.o : mode-switching.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
    $(TM_H) $(RTL_H) $(REGS_H) hard-reg-set.h $(FLAGS_H) insn-config.h \
    $(INSN_ATTR_H) $(RECOG_H) $(BASIC_BLOCK_H) $(TM_P_H) $(FUNCTION_H) \
-   output.h $(TREE_PASS_H) $(TIMEVAR_H) $(DF_H) $(TARGET_H) $(EMIT_RTL_H)
+   output.h $(TREE_PASS_H) $(TIMEVAR_H) $(DF_H) $(TARGET_H) $(EMIT_RTL_H) \
+   integrate.h
 tree-ssa-dce.o : tree-ssa-dce.c $(CONFIG_H) $(SYSTEM_H) $(TREE_H) \
     $(TREE_FLOW_H) $(DIAGNOSTIC_H) $(TIMEVAR_H) $(TM_H) \
     coretypes.h $(TREE_DUMP_H) $(TREE_PASS_H) $(FLAGS_H) $(BASIC_BLOCK_H) \
diff --git a/src/gcc-mainline/gcc/doc/md.texi b/src/gcc-mainline/gcc/doc/md.texi
index fd8423a..bc488eb 100644
--- a/src/gcc-mainline/gcc/doc/md.texi
+++ b/src/gcc-mainline/gcc/doc/md.texi
@@ -5196,6 +5196,13 @@ The @code{sibcall_epilogue} pattern must not clobber any arguments used for
 parameter passing or any stack slots for arguments passed to the current
 function.
 
+@cindex @code{use_initial_val} instruction pattern
+@item @samp{use_initial_val}
+This pattern, if defined, emits an insn that shows use a pseudo register
+created by @code{get_hard_reg_initial_val}.  This is useful if a port may
+introduce additional uses of this pseudo in late optimization passes, when
+the initial ones may already have been optimized away.
+
 @cindex @code{trap} instruction pattern
 @item @samp{trap}
 This pattern, if defined, signals an error, typically by causing some
diff --git a/src/gcc-mainline/gcc/integrate.c b/src/gcc-mainline/gcc/integrate.c
index dd75758..9a5c364 100644
--- a/src/gcc-mainline/gcc/integrate.c
+++ b/src/gcc-mainline/gcc/integrate.c
@@ -56,6 +56,7 @@ along with GCC; see the file COPYING3.  If not see
 typedef struct GTY(()) initial_value_pair {
   rtx hard_reg;
   rtx pseudo;
+  bool initialized;
 } initial_value_pair;
 typedef struct GTY(()) initial_value_struct {
   int num_entries;
@@ -239,6 +240,7 @@ get_hard_reg_initial_val (enum machine_mode mode, unsigned int regno)
 {
   struct initial_value_struct *ivs;
   rtx rv;
+  int entry;
 
   rv = has_hard_reg_initial_val (mode, regno);
   if (rv)
@@ -254,17 +256,19 @@ get_hard_reg_initial_val (enum machine_mode mode, unsigned int regno)
       crtl->hard_reg_initial_vals = ivs;
     }
 
-  if (ivs->num_entries >= ivs->max_entries)
+  entry = ivs->num_entries++;
+  if (entry >= ivs->max_entries)
     {
       ivs->max_entries += 5;
       ivs->entries = GGC_RESIZEVEC (initial_value_pair, ivs->entries,
 				    ivs->max_entries);
     }
 
-  ivs->entries[ivs->num_entries].hard_reg = gen_rtx_REG (mode, regno);
-  ivs->entries[ivs->num_entries].pseudo = gen_reg_rtx (mode);
+  ivs->entries[entry].hard_reg = gen_rtx_REG (mode, regno);
+  ivs->entries[entry].pseudo = gen_reg_rtx (mode);
+  ivs->entries[entry].initialized = false;
 
-  return ivs->entries[ivs->num_entries++].pseudo;
+  return ivs->entries[entry].pseudo;
 }
 
 /* See if get_hard_reg_initial_val has been used to create a pseudo
@@ -299,7 +303,16 @@ emit_initial_value_sets (void)
 
   start_sequence ();
   for (i = 0; i < ivs->num_entries; i++)
-    emit_move_insn (ivs->entries[i].pseudo, ivs->entries[i].hard_reg);
+    {
+      if (ivs->entries[i].initialized)
+	continue;
+      ivs->entries[i].initialized = true;
+      emit_move_insn (ivs->entries[i].pseudo, ivs->entries[i].hard_reg);
+#ifdef HAVE_use_initial_val
+      if (HAVE_use_initial_val)
+	emit_insn (gen_use_initial_val (ivs->entries[i].pseudo));
+#endif
+    }
   seq = get_insns ();
   end_sequence ();
 
diff --git a/src/gcc-mainline/gcc/mode-switching.c b/src/gcc-mainline/gcc/mode-switching.c
index 306fb5d..ce7e4d1 100644
--- a/src/gcc-mainline/gcc/mode-switching.c
+++ b/src/gcc-mainline/gcc/mode-switching.c
@@ -33,6 +33,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "output.h"
 #include "tm_p.h"
 #include "function.h"
+#include "integrate.h"
 #include "tree-pass.h"
 #include "timevar.h"
 #include "df.h"
@@ -753,6 +754,7 @@ rest_of_handle_mode_switching (void)
 {
 #ifdef OPTIMIZE_MODE_SWITCHING
   optimize_mode_switching ();
+  emit_initial_value_sets ();
 #endif /* OPTIMIZE_MODE_SWITCHING */
   return 0;
 }