2012-01-05 Paul Thomas <pault@gcc.gnu.org>

[pf3gnuchains/gcc-fork.git] / gcc / explow.c

diff --git a/gcc/explow.c b/gcc/explow.c
index f8262db..11dffed 100644 (file)
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -384,18 +384,23 @@ convert_memory_address_addr_space (enum machine_mode to_mode ATTRIBUTE_UNUSED,
 
     case PLUS:
     case MULT:
-      /* For addition we can safely permute the conversion and addition
-        operation if one operand is a constant and converting the constant
-        does not change it or if one operand is a constant and we are
-        using a ptr_extend instruction  (POINTERS_EXTEND_UNSIGNED < 0).
+      /* FIXME: For addition, we used to permute the conversion and
+        addition operation only if one operand is a constant and
+        converting the constant does not change it or if one operand
+        is a constant and we are using a ptr_extend instruction
+        (POINTERS_EXTEND_UNSIGNED < 0) even if the resulting address
+        may overflow/underflow.  We relax the condition to include
+        zero-extend (POINTERS_EXTEND_UNSIGNED > 0) since the other
+        parts of the compiler depend on it.  See PR 49721.
+
         We can always safely permute them if we are making the address
         narrower.  */
       if (GET_MODE_SIZE (to_mode) < GET_MODE_SIZE (from_mode)
          || (GET_CODE (x) == PLUS
              && CONST_INT_P (XEXP (x, 1))
-             && (XEXP (x, 1) == convert_memory_address_addr_space
-                                  (to_mode, XEXP (x, 1), as)
-                 || POINTERS_EXTEND_UNSIGNED < 0)))
+             && (POINTERS_EXTEND_UNSIGNED != 0
+                 || XEXP (x, 1) == convert_memory_address_addr_space
+                                       (to_mode, XEXP (x, 1), as))))
        return gen_rtx_fmt_ee (GET_CODE (x), to_mode,
                               convert_memory_address_addr_space
                                 (to_mode, XEXP (x, 0), as),
@@ -1057,6 +1062,20 @@ emit_stack_restore (enum save_level save_level, rtx sa)
   /* The default is that we use a move insn.  */
   rtx (*fcn) (rtx, rtx) = gen_move_insn;
 
+  /* If stack_realign_drap, the x86 backend emits a prologue that aligns both
+     STACK_POINTER and HARD_FRAME_POINTER.
+     If stack_realign_fp, the x86 backend emits a prologue that aligns only
+     STACK_POINTER. This renders the HARD_FRAME_POINTER unusable for accessing
+     aligned variables, which is reflected in ix86_can_eliminate.
+     We normally still have the realigned STACK_POINTER that we can use.
+     But if there is a stack restore still present at reload, it can trigger 
+     mark_not_eliminable for the STACK_POINTER, leaving no way to eliminate
+     FRAME_POINTER into a hard reg.
+     To prevent this situation, we force need_drap if we emit a stack
+     restore.  */
+  if (SUPPORTS_STACK_ALIGNMENT)
+    crtl->need_drap = true;
+
   /* See if this machine has anything special to do for this kind of save.  */
   switch (save_level)
     {
@@ -1375,6 +1394,9 @@ allocate_dynamic_stack_space (rtx size, unsigned size_align,
   else if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK)
     probe_stack_range (STACK_CHECK_PROTECT, size);
 
+  /* Don't let anti_adjust_stack emit notes.  */
+  suppress_reg_args_size = true;
+
   /* Perform the required allocation from the stack.  Some systems do
      this differently than simply incrementing/decrementing from the
      stack pointer, such as acquiring the space by calling malloc().  */
@@ -1425,7 +1447,6 @@ allocate_dynamic_stack_space (rtx size, unsigned size_align,
        }
 
       saved_stack_pointer_delta = stack_pointer_delta;
-      suppress_reg_args_size = true;
 
       if (flag_stack_check && STACK_CHECK_MOVING_SP)
        anti_adjust_stack_and_probe (size, false);
@@ -1436,13 +1457,14 @@ allocate_dynamic_stack_space (rtx size, unsigned size_align,
         The constant size alloca should preserve
         crtl->preferred_stack_boundary alignment.  */
       stack_pointer_delta = saved_stack_pointer_delta;
-      suppress_reg_args_size = false;
 
 #ifdef STACK_GROWS_DOWNWARD
       emit_move_insn (target, virtual_stack_dynamic_rtx);
 #endif
     }
 
+  suppress_reg_args_size = false;
+
   /* Finish up the split stack handling.  */
   if (final_label != NULL_RTX)
     {