gcc/

	Backport from trunk r225106.
	2015-06-28  Chung-Lin Tang <cltang@codesourcery.com>
	    Sandra Loosemore <sandra@codesourcery.com>

	* regrename.h (regrename_do_replace): Change to return bool.
	* regrename.c (rename_chains): Check return value of
	regname_do_replace.
	(regrename_do_replace): Re-validate the modified insns and
	return bool status.
	* config/aarch64/cortex-a57-fma-steering.c (rename_single_chain):
	Update to match rename_chains changes.
	* config/c6x/c6x.c (try_rename_operands): Assert that
	regrename_do_replace returns true.

Change-Id: Ib5cb97828c0963e7c9a2283f1569e76584c2cdd8

4 files changed, 45 insertions, 19 deletions

diff --git a/gcc/config/aarch64/cortex-a57-fma-steering.c b/gcc/config/aarch64/cortex-a57-fma-steering.c
index a86dd5a0904..42490eda155 100644
--- a/gcc/config/aarch64/cortex-a57-fma-steering.c
+++ b/gcc/config/aarch64/cortex-a57-fma-steering.c
@@ -291,11 +291,19 @@ rename_single_chain (du_head_p head, HARD_REG_SET *unavailable)
       return false;
     }
 
-  if (dump_file)
-    fprintf (dump_file, ", renamed as %s\n", reg_names[best_new_reg]);
-
-  regrename_do_replace (head, best_new_reg);
-  df_set_regs_ever_live (best_new_reg, true);
+  if (regrename_do_replace (head, best_new_reg))
+    {
+      if (dump_file)
+	fprintf (dump_file, ", renamed as %s\n", reg_names[best_new_reg]);
+      df_set_regs_ever_live (best_new_reg, true);
+    }
+  else
+    {
+      if (dump_file)
+	fprintf (dump_file, ", renaming as %s failed\n",
+		 reg_names[best_new_reg]);
+      return false;
+    }
   return true;
 }
 
diff --git a/gcc/config/c6x/c6x.c b/gcc/config/c6x/c6x.c
index 03f6b3f3f29..b56aec4c04d 100644
--- a/gcc/config/c6x/c6x.c
+++ b/gcc/config/c6x/c6x.c
@@ -3532,7 +3532,7 @@ try_rename_operands (rtx_insn *head, rtx_insn *tail, unit_req_table reqs,
   best_reg =
     find_rename_reg (this_head, super_class, &unavailable, old_reg, true);
 
-  regrename_do_replace (this_head, best_reg);
+  gcc_assert (regrename_do_replace (this_head, best_reg));
 
   count_unit_reqs (new_reqs, head, PREV_INSN (tail));
   merge_unit_reqs (new_reqs);
@@ -3545,7 +3545,7 @@ try_rename_operands (rtx_insn *head, rtx_insn *tail, unit_req_table reqs,
 	       unit_req_imbalance (reqs), unit_req_imbalance (new_reqs));
     }
   if (unit_req_imbalance (new_reqs) > unit_req_imbalance (reqs))
-    regrename_do_replace (this_head, old_reg);
+    gcc_assert (regrename_do_replace (this_head, old_reg));
   else
     memcpy (reqs, new_reqs, sizeof (unit_req_table));
 
diff --git a/gcc/regrename.c b/gcc/regrename.c
index f995ffa4cb7..3d85b651583 100644
--- a/gcc/regrename.c
+++ b/gcc/regrename.c
@@ -505,12 +505,20 @@ rename_chains (void)
 	  continue;
 	}
 
-      if (dump_file)
-	fprintf (dump_file, ", renamed as %s\n", reg_names[best_new_reg]);
-
-      regrename_do_replace (this_head, best_new_reg);
-      tick[best_new_reg] = ++this_tick;
-      df_set_regs_ever_live (best_new_reg, true);
+      if (regrename_do_replace (this_head, best_new_reg))
+	{
+	  if (dump_file)
+	    fprintf (dump_file, ", renamed as %s\n", reg_names[best_new_reg]);
+	  tick[best_new_reg] = ++this_tick;
+	  df_set_regs_ever_live (best_new_reg, true);
+	}
+      else
+	{
+	  if (dump_file)
+	    fprintf (dump_file, ", renaming as %s failed\n",
+		     reg_names[best_new_reg]);
+	  tick[reg] = ++this_tick;
+	}
     }
 }
 
@@ -936,7 +944,13 @@ regrename_analyze (bitmap bb_mask)
     bb->aux = NULL;
 }
 
-void
+/* Attempt to replace all uses of the register in the chain beginning with
+   HEAD with REG.  Returns true on success and false if the replacement is
+   rejected because the insns would not validate.  The latter can happen
+   e.g. if a match_parallel predicate enforces restrictions on register
+   numbering in its subpatterns.  */
+
+bool
 regrename_do_replace (struct du_head *head, int reg)
 {
   struct du_chain *chain;
@@ -950,22 +964,26 @@ regrename_do_replace (struct du_head *head, int reg)
       int reg_ptr = REG_POINTER (*chain->loc);
 
       if (DEBUG_INSN_P (chain->insn) && REGNO (*chain->loc) != base_regno)
-	INSN_VAR_LOCATION_LOC (chain->insn) = gen_rtx_UNKNOWN_VAR_LOC ();
+	validate_change (chain->insn, &(INSN_VAR_LOCATION_LOC (chain->insn)),
+			 gen_rtx_UNKNOWN_VAR_LOC (), true);
       else
 	{
-	  *chain->loc = gen_raw_REG (GET_MODE (*chain->loc), reg);
+	  validate_change (chain->insn, chain->loc, 
+			   gen_raw_REG (GET_MODE (*chain->loc), reg), true);
 	  if (regno >= FIRST_PSEUDO_REGISTER)
 	    ORIGINAL_REGNO (*chain->loc) = regno;
 	  REG_ATTRS (*chain->loc) = attr;
 	  REG_POINTER (*chain->loc) = reg_ptr;
 	}
-
-      df_insn_rescan (chain->insn);
     }
 
+  if (!apply_change_group ())
+    return false;
+
   mode = GET_MODE (*head->first->loc);
   head->regno = reg;
   head->nregs = hard_regno_nregs[reg][mode];
+  return true;
 }
 
 
diff --git a/gcc/regrename.h b/gcc/regrename.h
index 8dc9f71a730..bbe156dbc4e 100644
--- a/gcc/regrename.h
+++ b/gcc/regrename.h
@@ -91,6 +91,6 @@ extern void regrename_analyze (bitmap);
 extern du_head_p regrename_chain_from_id (unsigned int);
 extern int find_rename_reg (du_head_p, enum reg_class, HARD_REG_SET *, int,
 			    bool);
-extern void regrename_do_replace (du_head_p, int);
+extern bool regrename_do_replace (du_head_p, int);
 
 #endif