* alias.c: Update comments for ADDRESS.

        (nonlocal_reference_p): Look inside the ADDRESS to determine if
        it is a local memory reference.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@30210 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index cf97fbf..fa17678 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -4,6 +4,10 @@ Tue Oct 26 23:15:03 1999  Mark Mitchell  <mark@codesourcery.com>
 
 Tue Oct 26 23:29:18 1999  Jeffrey A Law  (law@cygnus.com)
 
+       * alias.c: Update comments for ADDRESS.
+       (nonlocal_reference_p): Look inside the ADDRESS to determine if
+       it is a local memory reference.
+
        * c-typeck.c (build_function_call): Check that the built-in
        function is of class BUILT_IN_NORMAL before trying to recongize
        it as BUILT_IN_ABS.

diff --git a/gcc/alias.c b/gcc/alias.c
index cc50c1b..59578d7 100644 (file)
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -121,12 +121,16 @@ static int nonlocal_reference_p         PROTO((rtx));
 
    A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF.  ADDRESS
    expressions represent certain special values: function arguments and
-   the stack, frame, and argument pointers.  The contents of an address
-   expression are not used (but they are descriptive for debugging);
-   only the address and mode matter.  Pointer equality, not rtx_equal_p,
-   determines whether two ADDRESS expressions refer to the same base
-   address.  The mode determines whether it is a function argument or
-   other special value. */
+   the stack, frame, and argument pointers.  
+
+   The contents of an ADDRESS is not normally used, the mode of the
+   ADDRESS determines whether the ADDRESS is a function argument or some
+   other special value.  Pointer equality, not rtx_equal_p, determines whether
+   two ADDRESS expressions refer to the same base address.
+
+   The only use of the contents of an ADDRESS is for determining if the
+   current function performs nonlocal memory memory references for the
+   purposes of marking the function as a constant function.  */
 
 static rtx *reg_base_value;
 static rtx *new_reg_base_value;
@@ -1422,8 +1426,19 @@ nonlocal_reference_p (x)
       base = find_base_term (XEXP (x, 0));
       if (base)
        {
-         /* Stack references are local.  */
-         if (GET_CODE (base) == ADDRESS && GET_MODE (base) == Pmode)
+         /* A Pmode ADDRESS could be a reference via the structure value
+            address or static chain.  Such memory references are nonlocal.
+
+            Thus, we have to examine the contents of the ADDRESS to find
+            out if this is a local reference or not.  */
+         if (GET_CODE (base) == ADDRESS
+             && GET_MODE (base) == Pmode
+             && (XEXP (base, 0) == stack_pointer_rtx
+                 || XEXP (base, 0) == arg_pointer_rtx
+#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
+                 || XEXP (base, 0) == hard_frame_pointer_rtx
+#endif
+                 || XEXP (base, 0) == frame_pointer_rtx))
            return 0;
          /* Constants in the function's constant pool are constant.  */
          if (GET_CODE (base) == SYMBOL_REF && CONSTANT_POOL_ADDRESS_P (base))