Re: REQ_EQUAL and mems hoisted out of loops

[Alan Modra <amodra at bigpond dot net dot au>]

On Thu, Mar 27, 2003 at 03:49:08PM -0800, Richard Henderson wrote:
> On Wed, Mar 26, 2003 at 07:19:33PM +1030, Alan Modra wrote:
> > 	(load_mems): Remove invalid REG_EQUAL notes after hoisting.
> 
> I think this is the wrong spot to handle this.
> Do it in replace_loop_mems instead.

Yeah, that's neater.

	* loop.c: Include tree.h.
	(find_mem_in_note_1, find_mem_in_note): New functions.
	(replace_loop_mems): Add "written" param.  Remove invalid REG_EQUAL
	notes after hoisting.
	(load_mems): Adjust replace_loop_mems call.
	* Makefile.in (loop.o): Add TREE_H to deps.

Currently regtesting.

Index: gcc/loop.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/loop.c,v
retrieving revision 1.449
diff -u -p -r1.449 loop.c
--- gcc/loop.c	27 Mar 2003 18:53:35 -0000	1.449
+++ gcc/loop.c	28 Mar 2003 01:47:03 -0000
@@ -39,6 +39,7 @@ Software Foundation, 59 Temple Place - S
 #include "coretypes.h"
 #include "tm.h"
 #include "rtl.h"
+#include "tree.h"
 #include "tm_p.h"
 #include "function.h"
 #include "expr.h"
@@ -328,10 +329,12 @@ static void update_reg_last_use PARAMS (
 static rtx next_insn_in_loop PARAMS ((const struct loop *, rtx));
 static void loop_regs_scan PARAMS ((const struct loop *, int));
 static int count_insns_in_loop PARAMS ((const struct loop *));
+static int find_mem_in_note_1 PARAMS ((rtx *, void *));
+static rtx find_mem_in_note PARAMS ((rtx));
 static void load_mems PARAMS ((const struct loop *));
 static int insert_loop_mem PARAMS ((rtx *, void *));
 static int replace_loop_mem PARAMS ((rtx *, void *));
-static void replace_loop_mems PARAMS ((rtx, rtx, rtx));
+static void replace_loop_mems PARAMS ((rtx, rtx, rtx, int));
 static int replace_loop_reg PARAMS ((rtx *, void *));
 static void replace_loop_regs PARAMS ((rtx insn, rtx, rtx));
 static void note_reg_stored PARAMS ((rtx, rtx, void *));
@@ -10033,7 +10036,7 @@ load_mems (loop)
 	      else
 	        /* Replace the memory reference with the shadow register.  */
 		replace_loop_mems (p, loop_info->mems[i].mem,
-				   loop_info->mems[i].reg);
+				   loop_info->mems[i].reg, written);
 	    }
 
 	  if (GET_CODE (p) == CODE_LABEL
@@ -10398,6 +10401,29 @@ try_swap_copy_prop (loop, replacement, r
     }
 }
 
+static int
+find_mem_in_note_1 (x, data)
+     rtx *x;
+     void *data;
+{
+  if (*x != NULL_RTX && GET_CODE (*x) == MEM)
+    {
+      rtx *res = (rtx *) data;
+      *res = *x;
+      return 1;
+    }
+  return 0;
+}
+
+static rtx
+find_mem_in_note (note)
+     rtx note;
+{
+  if (note && for_each_rtx (&note, find_mem_in_note_1, &note))
+    return note;
+  return NULL_RTX;
+}
+  
 /* Replace MEM with its associated pseudo register.  This function is
    called from load_mems via for_each_rtx.  DATA is actually a pointer
    to a structure describing the instruction currently being scanned
@@ -10440,10 +10466,11 @@ replace_loop_mem (mem, data)
 }
 
 static void
-replace_loop_mems (insn, mem, reg)
+replace_loop_mems (insn, mem, reg, written)
      rtx insn;
      rtx mem;
      rtx reg;
+     int written;
 {
   loop_replace_args args;
 
@@ -10452,6 +10479,27 @@ replace_loop_mems (insn, mem, reg)
   args.replacement = reg;
 
   for_each_rtx (&insn, replace_loop_mem, &args);
+
+  /* If we hoist a mem write out of the loop, then REG_EQUAL
+     notes referring to the mem are no longer valid.  */
+  if (written)
+    {
+      rtx note, sub;
+      rtx *link;
+
+      for (link = &REG_NOTES (insn); (note = *link); link = &XEXP (note, 1))
+	{
+	  if (REG_NOTE_KIND (note) == REG_EQUAL
+	      && (sub = find_mem_in_note (note))
+	      && alias_sets_conflict_p (MEM_ALIAS_SET (mem),
+					MEM_ALIAS_SET (sub)))
+	    {
+	      /* Remove the note.  */
+	      validate_change (NULL_RTX, link, XEXP (note, 1), 1);
+	      break;
+	    }
+	}
+    }
 }
 
 /* Replace one register with another.  Called through for_each_rtx; PX points
Index: gcc/Makefile.in
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Makefile.in,v
retrieving revision 1.1026
diff -u -p -r1.1026 Makefile.in
--- gcc/Makefile.in	23 Mar 2003 20:13:50 -0000	1.1026
+++ gcc/Makefile.in	28 Mar 2003 01:50:59 -0000
@@ -1616,7 +1616,8 @@ profile.o : profile.c $(CONFIG_H) $(SYST
    flags.h insn-config.h output.h $(REGS_H) $(EXPR_H) function.h \
    gcov-io.h gcov-iov.h toplev.h $(GGC_H) hard-reg-set.h $(BASIC_BLOCK_H) \
    $(TARGET_H) langhooks.h profile.h libfuncs.h gt-profile.h $(HASHTAB_H)
-loop.o : loop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) flags.h $(LOOP_H) \
+loop.o : loop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
+   $(TREE_H) flags.h $(LOOP_H) \
    insn-config.h $(REGS_H) hard-reg-set.h $(RECOG_H) $(EXPR_H) \
    real.h $(PREDICT_H) $(BASIC_BLOCK_H) function.h cfgloop.h \
    toplev.h varray.h except.h cselib.h $(OPTABS_H) $(TM_P_H)

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre