* 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

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fd67f31..52e50a8 100644 (file)
--- 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 c910278..ca28278 100644 (file)
--- 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 5014437..dbc8b33 100644 (file)
--- 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"