* alpha.md (nt_lda): New pattern.

        * alpha.c (alpha_expand_prologue): Use it for large frames
        under windows nt.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@26565 138bc75d-0d04-0410-961f-82ee72b054a4

3 files changed, 38 insertions, 16 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fd67f315e45..52e50a8ce84 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+Tue Apr 20 16:38:11 1999  Richard Henderson  <rth@cygnus.com>
+
+	* alpha.md (nt_lda): New pattern. 
+	* alpha.c (alpha_expand_prologue): Use it for large frames 
+	under windows nt.
+
 Tue Apr 20 17:57:14 1999  Catherine Moore  <clm@cygnus.com>
 
         * config/arm/arm.md (movhi):  Add check for odd offset.
diff --git a/gcc/config/alpha/alpha.c b/gcc/config/alpha/alpha.c
index c910278a00c..ca282786aca 100644
--- a/gcc/config/alpha/alpha.c
+++ b/gcc/config/alpha/alpha.c
@@ -3421,6 +3421,7 @@ alpha_expand_prologue ()
       HOST_WIDE_INT leftover = frame_size + 4096 - blocks * 8192;
       rtx ptr = gen_rtx_REG (DImode, 22);
       rtx count = gen_rtx_REG (DImode, 23);
+      rtx seq;
 
       emit_move_insn (count, GEN_INT (blocks));
       emit_insn (gen_adddi3 (ptr, stack_pointer_rtx, GEN_INT (4096)));
@@ -3441,33 +3442,37 @@ alpha_expand_prologue ()
 	  /* For NT stack unwind (done by 'reverse execution'), it's
 	     not OK to take the result of a loop, even though the value
 	     is already in ptr, so we reload it via a single operation
-	     and add it to sp.  */
+	     and subtract it to sp. 
+
+	     Yes, that's correct -- we have to reload the whole constant
+	     into a temporary via ldah+lda then subtract from sp.  To
+	     ensure we get ldah+lda, we use a special pattern.  */
 
 	  HOST_WIDE_INT lo, hi;
 	  lo = ((-frame_size & 0xffff) ^ 0x8000) - 0x8000;
 	  hi = -frame_size - lo;
 
-	  FRP (emit_insn (gen_adddi3 (ptr, stack_pointer_rtx, GEN_INT (hi))));
-	  FRP (emit_insn (gen_adddi3 (stack_pointer_rtx, ptr, GEN_INT (lo))));
+	  emit_move_insn (ptr, GEN_INT (hi));
+	  emit_insn (gen_nt_lda (ptr, GEN_INT (lo)));
+	  seq = emit_insn (gen_subdi3 (stack_pointer_rtx, stack_pointer_rtx,
+				       ptr));
 	}
       else
 	{
-	  rtx seq;
-
 	  seq = emit_insn (gen_adddi3 (stack_pointer_rtx, ptr,
 				       GEN_INT (-leftover)));
-
-	  /* This alternative is special, because the DWARF code cannot
-	     possibly intuit through the loop above.  So we invent this
-	     note it looks at instead.  */
-	  RTX_FRAME_RELATED_P (seq) = 1;
-	  REG_NOTES (seq)
-	    = gen_rtx_EXPR_LIST (REG_FRAME_RELATED_EXPR,
-				 gen_rtx_SET (VOIDmode, stack_pointer_rtx,
-				   gen_rtx_PLUS (Pmode, stack_pointer_rtx,
-						 GEN_INT (-frame_size))),
-				 REG_NOTES (seq));
 	}
+
+      /* This alternative is special, because the DWARF code cannot
+         possibly intuit through the loop above.  So we invent this
+         note it looks at instead.  */
+      RTX_FRAME_RELATED_P (seq) = 1;
+      REG_NOTES (seq)
+        = gen_rtx_EXPR_LIST (REG_FRAME_RELATED_EXPR,
+			     gen_rtx_SET (VOIDmode, stack_pointer_rtx,
+			       gen_rtx_PLUS (Pmode, stack_pointer_rtx,
+					     GEN_INT (-frame_size))),
+			     REG_NOTES (seq));
     }
 
   /* Cope with very large offsets to the register save area.  */
diff --git a/gcc/config/alpha/alpha.md b/gcc/config/alpha/alpha.md
index 501443799af..dbc8b33d18e 100644
--- a/gcc/config/alpha/alpha.md
+++ b/gcc/config/alpha/alpha.md
@@ -29,6 +29,7 @@
 ;;	3	mskxh
 ;;	4	cvtlq
 ;;	5	cvtql
+;;	6	nt_lda
 ;;	
 ;; UNSPEC_VOLATILE:
 ;;
@@ -5161,6 +5162,16 @@
     }
 }")
 
+;; In creating a large stack frame, NT _must_ use ldah+lda to load
+;; the frame size into a register.  We use this pattern to ensure
+;; we get lda instead of addq.
+(define_insn "nt_lda"
+  [(set (match_operand:DI 0 "register_operand" "r")
+	(unspec:DI [(match_dup 0)
+		    (match_operand:DI 1 "const_int_operand" "n")] 6))]
+  ""
+  "lda %0,%1(%0)")
+
 (define_expand "builtin_longjmp"
   [(unspec_volatile [(match_operand 0 "register_operand" "r")] 3)]
   "! TARGET_OPEN_VMS && ! TARGET_WINDOWS_NT"