* attribs.c (decl_attributes): Avoid emitting a warning if

	ATTR_FLAG_BUILT_IN.
	* doc/rtl.texi (CALL_INSN_FUNCTION_USAGE): Use lowercase for rtx
	codes.  Document meaning of sets inside CALL_INSN_FUNCTION_USAGE.
	* c-family/c-common.c (DEF_ATTR_STRING): Define and undefine as
	necessary.
	* builtin-attrs.def (DEF_ATTR_FOR_STRING): Define.  Use it to
	define a string "1".
	(ATTR_RET1_NOTHROW_NONNULL_LEAF): New attr definition.
	* builtins.def (BUILT_IN_MEMCPY, BUILT_IN_MEMMOVE, BUILT_IN_MEMSET,
	BUILT_IN_STRCPY): Use it for these functions.
	* postreload.c (reload_combine): Deal with SETs inside
	CALL_INSN_FUNCTION_USAGE.
	* caller-save.c (setup_save_areas, save_call_clobbered_regs):
	Look for REG_RETURNED notes and use a cheap restore if possible.
	* ira-int.h (struct ira_allocno): New member cheap_calls_crossed_num.
	(ALLOCNO_CHEAP_CALLS_CROSSED_NUM): New macro.
	* ira-build.c (ira_create_allocno, create_cap_allocno,
	propagate_allocno_info, propagate_some_info_from_allocno,
	copy_info_to_removed_store_destination, ira_flattening): Handle it.
	* ira-lives.c (pseudo_regno_single_word_and_live_p,
	find_call_crossed_cheap_reg): New static functions.
	(process_bb_node_lives): Look for SETs in CALL_INSN_FUNCTION_USAGE,
	and set ALLOCNO_CHEAP_CALLS_CROSSED_NUM if possible.  Also make
	a REG_RETURNED note in that case.
	* ira.c (setup_reg_renumber): Change assert to allow cases where
	allocnos only cross calls for which they are cheap to restore.
	* ira-costs.c (ira_tune_allocno_costs): Compare
	ALLOCNO_CALLS_CROSSED_NUM to ALLOCNO_CHEAP_CALLS_CROSSED_NUM rather
	than 0.
	* reg-notes.def (REG_RETURNED): New note.
	* cse.c (cse_insn): Likewise.
	* sched-deps.c (sched_analyze_insn): Likewise.
	* expr.c (init_block_move_fn): Set a "fn spec" attribute.
	* calls.c (decl_return_flags): New static function.
	(expand_call): Generate a SET in CALL_INSN_FUNCTION_USAGE for
	functions that return one of their arguments.
	* lto/lto-lang.c (handle_fnspec_attribute): New static function.
	(lto_attribute_table): Add "fn spec".
	(DEF_ATTR_STRING): Define and undefine along with the other macros.
	* regcprop.c (struct kill_set_value_data): New.
	(kill_set_value): Interpret data as a pointer to such a struct.
	Do nothing if the caller wants the register to be ignored.
	(copyprop_hardreg_forward_1): Handle SETs in CALL_INSN_FUNCTION_USAGE.

testsuite/
	* gcc.target/i386/retarg.c: New test.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@187459 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 30 insertions, 3 deletions

diff --git a/gcc/caller-save.c b/gcc/caller-save.c
index 39bccc4fc8e..c8f3b145946 100644
--- a/gcc/caller-save.c
+++ b/gcc/caller-save.c
@@ -433,6 +433,8 @@ setup_save_areas (void)
   /* Create hard reg saved regs.  */
   for (chain = reload_insn_chain; chain != 0; chain = next)
     {
+      rtx cheap;
+
       insn = chain->insn;
       next = chain->next;
       if (!CALL_P (insn)
@@ -466,6 +468,9 @@ setup_save_areas (void)
 	      new_saved_hard_reg (regno, freq);
 	    SET_HARD_REG_BIT (hard_regs_used, regno);
 	  }
+      cheap = find_reg_note (insn, REG_RETURNED, NULL);
+      if (cheap)
+	cheap = XEXP (cheap, 0);
       /* Look through all live pseudos, mark their hard registers.  */
       EXECUTE_IF_SET_IN_REG_SET
 	(&chain->live_throughout, FIRST_PSEUDO_REGISTER, regno, rsi)
@@ -473,7 +478,7 @@ setup_save_areas (void)
 	  int r = reg_renumber[regno];
 	  int bound;
 
-	  if (r < 0)
+	  if (r < 0 || regno_reg_rtx[regno] == cheap)
 	    continue;
 
 	  bound = r + hard_regno_nregs[r][PSEUDO_REGNO_MODE (regno)];
@@ -508,12 +513,18 @@ setup_save_areas (void)
       memset (saved_reg_conflicts, 0, saved_regs_num * saved_regs_num);
       for (chain = reload_insn_chain; chain != 0; chain = next)
 	{
+	  rtx cheap;
 	  call_saved_regs_num = 0;
 	  insn = chain->insn;
 	  next = chain->next;
 	  if (!CALL_P (insn)
 	      || find_reg_note (insn, REG_NORETURN, NULL))
 	    continue;
+
+	  cheap = find_reg_note (insn, REG_RETURNED, NULL);
+	  if (cheap)
+	    cheap = XEXP (cheap, 0);
+
 	  REG_SET_TO_HARD_REG_SET (hard_regs_to_save,
 				   &chain->live_throughout);
 	  COPY_HARD_REG_SET (used_regs, call_used_reg_set);
@@ -546,7 +557,7 @@ setup_save_areas (void)
 	      int r = reg_renumber[regno];
 	      int bound;
 
-	      if (r < 0)
+	      if (r < 0 || regno_reg_rtx[regno] == cheap)
 		continue;
 
 	      bound = r + hard_regno_nregs[r][PSEUDO_REGNO_MODE (regno)];
@@ -796,6 +807,11 @@ save_call_clobbered_regs (void)
 	      unsigned regno;
 	      HARD_REG_SET hard_regs_to_save;
 	      reg_set_iterator rsi;
+	      rtx cheap;
+
+	      cheap = find_reg_note (insn, REG_RETURNED, NULL);
+	      if (cheap)
+		cheap = XEXP (cheap, 0);
 
 	      /* Use the register life information in CHAIN to compute which
 		 regs are live during the call.  */
@@ -817,7 +833,7 @@ save_call_clobbered_regs (void)
 		  int nregs;
 		  enum machine_mode mode;
 
-		  if (r < 0)
+		  if (r < 0 || regno_reg_rtx[regno] == cheap)
 		    continue;
 		  nregs = hard_regno_nregs[r][PSEUDO_REGNO_MODE (regno)];
 		  mode = HARD_REGNO_CALLER_SAVE_MODE
@@ -851,6 +867,17 @@ save_call_clobbered_regs (void)
 	      for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
 		if (TEST_HARD_REG_BIT (hard_regs_saved, regno))
 		  n_regs_saved++;
+	      
+	      if (cheap
+		  && HARD_REGISTER_P (cheap)
+		  && TEST_HARD_REG_BIT (call_used_reg_set, REGNO (cheap)))
+		{
+		  rtx call_set = single_set (insn);
+		  rtx dest = SET_DEST (call_set);
+		  rtx pat = gen_rtx_SET (VOIDmode, cheap,
+					 copy_rtx (dest));
+		  chain = insert_one_insn (chain, 0, -1, pat);
+		}
 	    }
           last = chain;
 	}