reload1.c (eliminate_regs): Delete LOAD_EXTENDED_OP code that boiled down to && ! 0.

        * reload1.c (eliminate_regs): Delete LOAD_EXTENDED_OP code that
        boiled down to && ! 0.
        * reload.c (find_reloads): Always force (subreg (mem)) to be
        reloaded if WORD_REGISTER_OPERATIONS.
        * reload.c (find_reloads_toplev): Handle arbitrary non-paradoxical
        SUBREGs of CONST_INTs.
        * reload.c (push_reload): If WORD_REGISTER_OPERATIONS, reload the
        SUBREG_REG if the word count is unchanged, also in the input reload
        case.  Disable non-applicable sanity checks.
        * reload.c (push_reload): In WORD_REGISTER_OPERATIONS code, add test
        to require the SUBREG mode to be smaller than the SUBREG_REG mode.
        * reload1.c (eliminate_regs): Likewise.
        * reload.c (push_reload): If WORD_REGISTER_OPERATIONS, reload the
        SUBREG_REG if the word count is unchanged.
        * reload1.c (eliminate_regs) [case SET]: If W_R_O, preserve
        subregs of identical word size for push_reload.
Various alpha fixes from the mainline sources.

Co-Authored-By: J"orn Rennecke <amylaar@cygnus.co.uk>
Co-Authored-By: Jim Wilson <wilson@cygnus.com>

From-SVN: r19336

3 files changed, 95 insertions, 34 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e1ca3cf3e5b..4b5c39d1b51 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,29 @@
+Mon Apr 20 02:17:37 1998  Richard Henderson  <rth@cygnus.com>               
+			  Jim Wilson  <wilson@cygnus.com>
+			  J"orn Rennecke <amylaar@cygnus.co.uk>
+
+	* reload1.c (eliminate_regs): Delete LOAD_EXTENDED_OP code that
+	boiled down to && ! 0.                                         
+
+	* reload.c (find_reloads): Always force (subreg (mem)) to be
+	reloaded if WORD_REGISTER_OPERATIONS.
+
+	* reload.c (find_reloads_toplev): Handle arbitrary non-paradoxical    
+	SUBREGs of CONST_INTs.                                         
+
+	* reload.c (push_reload): If WORD_REGISTER_OPERATIONS, reload the 
+	SUBREG_REG if the word count is unchanged, also in the input reload   
+	case.  Disable non-applicable sanity checks.
+
+	* reload.c (push_reload): In WORD_REGISTER_OPERATIONS code, add test
+	to require the SUBREG mode to be smaller than the SUBREG_REG mode.
+	* reload1.c (eliminate_regs): Likewise.                               
+        
+	* reload.c (push_reload): If WORD_REGISTER_OPERATIONS, reload the
+	SUBREG_REG if the word count is unchanged.           
+	* reload1.c (eliminate_regs) [case SET]: If W_R_O, preserve
+	subregs of identical word size for push_reload.                 
+
 Mon Apr 20 00:58:48 1998  H.J. Lu  (hjl@gnu.org)
 
 	* reg-stack.c (subst_asm_stack_regs): Change to return the last
diff --git a/gcc/reload.c b/gcc/reload.c
index 4b48a6c3171..a979550d793 100644
--- a/gcc/reload.c
+++ b/gcc/reload.c
@@ -890,6 +890,13 @@ push_reload (in, out, inloc, outloc, class,
 		      && INTEGRAL_MODE_P (GET_MODE (SUBREG_REG (in)))
 		      && LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (in))) != NIL)
 #endif
+#ifdef WORD_REGISTER_OPERATIONS
+		  || ((GET_MODE_SIZE (inmode)
+		       < GET_MODE_SIZE (GET_MODE (SUBREG_REG (in))))
+		      && ((GET_MODE_SIZE (inmode) - 1) / UNITS_PER_WORD ==
+			  ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (in))) - 1)
+			   / UNITS_PER_WORD)))
+#endif
 		  ))
 	  || (GET_CODE (SUBREG_REG (in)) == REG
 	      && REGNO (SUBREG_REG (in)) < FIRST_PSEUDO_REGISTER
@@ -927,7 +934,7 @@ push_reload (in, out, inloc, outloc, class,
       in_subreg_loc = inloc;
       inloc = &SUBREG_REG (in);
       in = *inloc;
-#ifndef LOAD_EXTEND_OP
+#if ! defined (LOAD_EXTEND_OP) && ! defined (WORD_REGISTER_OPERATIONS)
       if (GET_CODE (in) == MEM)
 	/* This is supposed to happen only for paradoxical subregs made by
 	   combine.c.  (SUBREG (MEM)) isn't supposed to occur other ways.  */
@@ -989,7 +996,15 @@ push_reload (in, out, inloc, outloc, class,
 		&& REGNO (SUBREG_REG (out)) >= FIRST_PSEUDO_REGISTER)
 	       || GET_CODE (SUBREG_REG (out)) == MEM)
 	      && ((GET_MODE_SIZE (outmode)
-		   > GET_MODE_SIZE (GET_MODE (SUBREG_REG (out))))))
+		   > GET_MODE_SIZE (GET_MODE (SUBREG_REG (out))))
+#ifdef WORD_REGISTER_OPERATIONS
+		  || ((GET_MODE_SIZE (outmode)
+		       < GET_MODE_SIZE (GET_MODE (SUBREG_REG (out))))
+		      && ((GET_MODE_SIZE (outmode) - 1) / UNITS_PER_WORD ==
+			  ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (out))) - 1)
+			   / UNITS_PER_WORD)))
+#endif
+	          ))
 	  || (GET_CODE (SUBREG_REG (out)) == REG
 	      && REGNO (SUBREG_REG (out)) < FIRST_PSEUDO_REGISTER
 	      && ((GET_MODE_SIZE (outmode) <= UNITS_PER_WORD
@@ -1023,7 +1038,7 @@ push_reload (in, out, inloc, outloc, class,
       out_subreg_loc = outloc;
       outloc = &SUBREG_REG (out);
       out = *outloc; 
-#ifndef LOAD_EXTEND_OP
+#if ! defined (LOAD_EXTEND_OP) && ! defined (WORD_REGISTER_OPERATIONS)
      if (GET_CODE (out) == MEM
 	  && GET_MODE_SIZE (GET_MODE (out)) > GET_MODE_SIZE (outmode))
 	abort ();
@@ -2757,10 +2772,20 @@ find_reloads (insn, replace, ind_levels, live_known, reload_reg_p)
 		     register access.  If the data is, in fact, in memory we
 		     must always load using the size assumed to be in the
 		     register and let the insn do the different-sized 
-		     accesses.  */
+		     accesses.
+
+		     This is doubly true if WORD_REGISTER_OPERATIONS.  In 
+		     this case eliminate_regs has left non-paradoxical
+		     subregs for push_reloads to see.  Make sure it does
+		     by forcing the reload.
+
+		     ??? When is it right at this stage to have a subreg
+		     of a mem that is _not_ to be handled specialy?  IMO
+		     those should have been reduced to just a mem.  */
 		  || ((GET_CODE (operand) == MEM
 		       || (GET_CODE (operand)== REG
 			   && REGNO (operand) >= FIRST_PSEUDO_REGISTER))
+#ifndef WORD_REGISTER_OPERATIONS
 		      && (((GET_MODE_BITSIZE (GET_MODE (operand))
 			    < BIGGEST_ALIGNMENT)
 			   && (GET_MODE_SIZE (operand_mode[i])
@@ -2775,7 +2800,9 @@ find_reloads (insn, replace, ind_levels, live_known, reload_reg_p)
 			      && INTEGRAL_MODE_P (GET_MODE (operand))
 			      && LOAD_EXTEND_OP (GET_MODE (operand)) != NIL)
 #endif
-			  ))
+			  )
+#endif
+		      )
 		  /* Subreg of a hard reg which can't handle the subreg's mode
 		     or which would handle that mode in the wrong number of
 		     registers for subregging to work.  */
@@ -4162,6 +4189,29 @@ find_reloads_toplev (x, opnum, type, ind_levels, is_set_dest)
 				     GET_MODE (SUBREG_REG (x)))) != 0)
 	return tem;
 
+      /* If the SUBREG is wider than a word, the above test will fail.
+	 For example, we might have a SImode SUBREG of a DImode SUBREG_REG
+	 for a 16 bit target, or a DImode SUBREG of a TImode SUBREG_REG for
+	 a 32 bit target.  We still can - and have to - handle this
+	 for non-paradoxical subregs of CONST_INTs.  */
+      if (regno >= FIRST_PSEUDO_REGISTER && reg_renumber[regno] < 0
+	  && reg_equiv_constant[regno] != 0
+	  && GET_CODE (reg_equiv_constant[regno]) == CONST_INT
+	  && (GET_MODE_SIZE (GET_MODE (x))
+	      < GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
+	  {
+	    int shift = SUBREG_WORD (x) * BITS_PER_WORD;
+	    if (WORDS_BIG_ENDIAN)
+	      shift = (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x)))
+		       - GET_MODE_BITSIZE (GET_MODE (x))
+		       - shift);
+	    /* Here we use the knowledge that CONST_INTs have a
+	       HOST_WIDE_INT field.  */
+	    if (shift >= HOST_BITS_PER_WIDE_INT)
+	      shift = HOST_BITS_PER_WIDE_INT - 1;
+	    return GEN_INT (INTVAL (reg_equiv_constant[regno]) >> shift);
+	  }
+
       if (regno >= FIRST_PSEUDO_REGISTER && reg_renumber[regno] < 0
 	  && reg_equiv_constant[regno] != 0
 	  && GET_MODE (reg_equiv_constant[regno]) == VOIDmode)
diff --git a/gcc/reload1.c b/gcc/reload1.c
index cbb41308ddb..565ba4b7802 100644
--- a/gcc/reload1.c
+++ b/gcc/reload1.c
@@ -3108,30 +3108,21 @@ eliminate_regs (x, mem_mode, insn, storing)
 	  int x_size = GET_MODE_SIZE (GET_MODE (x));
 	  int new_size = GET_MODE_SIZE (GET_MODE (new));
 
-	  /* When asked to spill a partial word subreg, we need to go
-	     ahead and spill the whole thing against the possibility
-	     that we reload the whole reg and find garbage at the top.  */
-	  if (storing
-	      && GET_CODE (new) == MEM
-	      && x_size < new_size
-	      && ((x_size + UNITS_PER_WORD-1) / UNITS_PER_WORD
-		  == (new_size + UNITS_PER_WORD-1) / UNITS_PER_WORD))
-	    return new;
-	  else if (GET_CODE (new) == MEM
-		   && x_size <= new_size
-#ifdef LOAD_EXTEND_OP
-	           /* On these machines we will be reloading what is
-		      inside the SUBREG if it originally was a pseudo and
-		      the inner and outer modes are both a word or
-		      smaller.  So leave the SUBREG then.  */
-	           && ! (GET_CODE (SUBREG_REG (x)) == REG
-		         && x_size <= UNITS_PER_WORD
-		         && new_size <= UNITS_PER_WORD
-		         && x_size > new_size
-		         && INTEGRAL_MODE_P (GET_MODE (new))
-		         && LOAD_EXTEND_OP (GET_MODE (new)) != NIL)
+	  if (GET_CODE (new) == MEM
+	      && ((x_size < new_size
+#ifdef WORD_REGISTER_OPERATIONS
+		   /* On these machines, combine can create rtl of the form
+		      (set (subreg:m1 (reg:m2 R) 0) ...)
+		      where m1 < m2, and expects something interesting to 
+		      happen to the entire word.  Moreover, it will use the
+		      (reg:m2 R) later, expecting all bits to be preserved.
+		      So if the number of words is the same, preserve the 
+		      subreg so that push_reloads can see it.  */
+		   && ! ((x_size-1)/UNITS_PER_WORD == (new_size-1)/UNITS_PER_WORD)
 #endif
-	           )
+		   )
+		  || (x_size == new_size))
+	      )
 	    {
 	      int offset = SUBREG_WORD (x) * UNITS_PER_WORD;
 	      enum machine_mode mode = GET_MODE (x);
@@ -3271,12 +3262,6 @@ eliminate_regs (x, mem_mode, insn, storing)
 	    && GET_CODE (insn) != INSN_LIST)
 	  emit_insn_after (gen_rtx (CLOBBER, VOIDmode, SET_DEST (x)), insn);
 
-	/* If SET_DEST was a partial-word subreg, NEW0 may have been widened
-	   to spill the entire register (see SUBREG case above).  If the 
-	   widths of SET_DEST and NEW0 no longer match, adjust NEW1.  */
-	if (GET_MODE (SET_DEST (x)) != GET_MODE (new0))
-	  new1 = gen_rtx (SUBREG, GET_MODE (new0), new1, 0);
-
 	if (new0 != SET_DEST (x) || new1 != SET_SRC (x))
 	  return gen_rtx (SET, VOIDmode, new0, new1);
       }