diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index edd63af9f0d..b18311df517 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,11 @@
 Thu Feb  1 07:22:41 2001  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>
 
+	* builtins.c (expand_builtin_alloca): allocate_dynamic_stack_space
+	returns Pmode pseudo, but we need ptr_mode.
+	* explow.c (allocate_dynamic_stack_space): Use plus_constant.
+	Remove bogus conversions; use HOST_WIDE_INT for size.
+	Don't use TARGET if wrong mode.
+
 	* config/i386/i386.c (ix86_compute_frame_size): Allow
 	stack_alignment_needed to be non-default even if size is zero.
 
diff --git a/gcc/builtins.c b/gcc/builtins.c
index a49fc17325e..1a6d87f77d4 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -3095,12 +3095,14 @@ expand_builtin_frame_address (exp)
 /* Expand a call to the alloca builtin, with arguments ARGLIST.  Return 0 if
    we failed and the caller should emit a normal call, otherwise try to get
    the result in TARGET, if convenient.  */
+
 static rtx
 expand_builtin_alloca (arglist, target)
      tree arglist;
      rtx target;
 {
   rtx op0;
+  rtx result;
 
   if (!validate_arglist (arglist, INTEGER_TYPE, VOID_TYPE))
     return 0;
@@ -3109,13 +3111,20 @@ expand_builtin_alloca (arglist, target)
   op0 = expand_expr (TREE_VALUE (arglist), NULL_RTX, VOIDmode, 0);
 
   /* Allocate the desired space.  */
-  return allocate_dynamic_stack_space (op0, target, BITS_PER_UNIT);
+  result = allocate_dynamic_stack_space (op0, target, BITS_PER_UNIT);
+
+#ifdef POINTERS_EXTEND_UNSIGNED
+  result = convert_memory_address (ptr_mode, result);
+#endif
+
+  return result;
 }
 
 /* Expand a call to the ffs builtin.  The arguments are in ARGLIST.
    Return 0 if a normal call should be emitted rather than expanding the
    function in-line.  If convenient, the result should be placed in TARGET.
    SUBTARGET may be used as the target for computing one of EXP's operands.  */
+
 static rtx
 expand_builtin_ffs (arglist, target, subtarget)
      tree arglist;
@@ -3138,6 +3147,7 @@ expand_builtin_ffs (arglist, target, subtarget)
 
 /* If the string passed to fputs is a constant and is one character
    long, we attempt to transform this call into __builtin_fputc(). */
+
 static rtx
 expand_builtin_fputs (arglist, ignore)
      tree arglist;
diff --git a/gcc/explow.c b/gcc/explow.c
index aa1e8a69270..d36ceffa440 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -1294,15 +1294,10 @@ allocate_dynamic_stack_space (size, target, known_align)
 #endif
 
   if (MUST_ALIGN)
-    {
-      if (GET_CODE (size) == CONST_INT)
-	size = GEN_INT (INTVAL (size)
-			+ (BIGGEST_ALIGNMENT / BITS_PER_UNIT - 1));
-      else
-	size = expand_binop (Pmode, add_optab, size,
-			     GEN_INT (BIGGEST_ALIGNMENT / BITS_PER_UNIT - 1),
-			     NULL_RTX, 1, OPTAB_LIB_WIDEN);
-    }
+    size
+      = force_operand (plus_constant (size, 
+				      BIGGEST_ALIGNMENT / BITS_PER_UNIT - 1),
+		       NULL_RTX);
 
 #ifdef SETJMP_VIA_SAVE_AREA
   /* If setjmp restores regs from a save area in the stack frame,
@@ -1325,12 +1320,12 @@ allocate_dynamic_stack_space (size, target, known_align)
 #if !defined(PREFERRED_STACK_BOUNDARY) || !defined(MUST_ALIGN) || (PREFERRED_STACK_BOUNDARY != BIGGEST_ALIGNMENT)
 	/* If anyone creates a target with these characteristics, let them
 	   know that our optimization cannot work correctly in such a case.  */
-	abort();
+	abort ();
 #endif
 
 	if (GET_CODE (size) == CONST_INT)
 	  {
-	    int new = INTVAL (size) / align * align;
+	    HOST_WIDE_INT new = INTVAL (size) / align * align;
 
 	    if (INTVAL (size) != new)
 	      setjmpless_size = GEN_INT (new);
@@ -1395,9 +1390,10 @@ allocate_dynamic_stack_space (size, target, known_align)
   if (flag_stack_check && ! STACK_CHECK_BUILTIN)
     probe_stack_range (STACK_CHECK_MAX_FRAME_SIZE + STACK_CHECK_PROTECT, size);
 
-  /* Don't use a TARGET that isn't a pseudo.  */
+  /* Don't use a TARGET that isn't a pseudo or is the wrong mode.  */
   if (target == 0 || GET_CODE (target) != REG
-      || REGNO (target) < FIRST_PSEUDO_REGISTER)
+      || REGNO (target) < FIRST_PSEUDO_REGISTER
+      || GET_MODE (target) != Pmode)
     target = gen_reg_rtx (Pmode);
 
   mark_reg_pointer (target, known_align);
@@ -1422,7 +1418,6 @@ allocate_dynamic_stack_space (size, target, known_align)
       if (mode == VOIDmode)
 	mode = Pmode;
 
-      size = convert_modes (mode, ptr_mode, size, 1);
       pred = insn_data[(int) CODE_FOR_allocate_stack].operand[1].predicate;
       if (pred && ! ((*pred) (size, mode)))
 	size = copy_to_mode_reg (mode, size);
@@ -1435,7 +1430,6 @@ allocate_dynamic_stack_space (size, target, known_align)
 #ifndef STACK_GROWS_DOWNWARD
       emit_move_insn (target, virtual_stack_dynamic_rtx);
 #endif
-      size = convert_modes (Pmode, ptr_mode, size, 1);
 
       /* Check stack bounds if necessary.  */
       if (current_function_limit_stack)
@@ -1474,6 +1468,7 @@ allocate_dynamic_stack_space (size, target, known_align)
 				 REG_NOTES (note_target));
 	}
 #endif /* SETJMP_VIA_SAVE_AREA */
+
 #ifdef STACK_GROWS_DOWNWARD
   emit_move_insn (target, virtual_stack_dynamic_rtx);
 #endif