* rtlanal.c (rtx_unstable_p): The pic register is stable

	(within one function) and the actual rtx should be used
	when checking the registers.
	(rtx_addr_can_trap_p): Pic memory addresses can't trap.

	* alias.c (true_dependence, write_dependence_p): Fix
	bug in previous patch.

	* i386.c (ix86_GOT_alias_set): New.
	(legitimize_pic_address): Use it.

	* rtlanal.c (rtx_unstable_p): An unchanging MEM is
	only stable if its address is stable.
	(rtx_varies_p): An unchanging MEM can't vary if
	its address doesn't vary.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@35900 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 56 insertions, 21 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 303aea56ff6..cef575916e1 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,21 @@
+Tue Aug 22 23:53:27 EDT 2000  John Wehle  (john@feith.com)
+
+	* rtlanal.c (rtx_unstable_p): The pic register is stable
+	(within one function) and the actual rtx should be used
+	when checking the registers.
+	(rtx_addr_can_trap_p): Pic memory addresses can't trap.
+
+	* alias.c (true_dependence, write_dependence_p): Fix
+	bug in previous patch.
+
+	* i386.c (ix86_GOT_alias_set): New.
+	(legitimize_pic_address): Use it.
+
+	* rtlanal.c (rtx_unstable_p): An unchanging MEM is
+	only stable if its address is stable.
+	(rtx_varies_p): An unchanging MEM can't vary if
+	its address doesn't vary.
+
 2000-08-22  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* c-parse.in (unop +): Restrict -Wtraditional warnings to user code.
diff --git a/gcc/alias.c b/gcc/alias.c
index bfa450595d5..5d96dad2df2 100644
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -1584,18 +1584,18 @@ true_dependence (mem, mem_mode, x, varies)
   if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
     return 0;
 
-  base = find_base_term (x);
-  if (base && (GET_CODE (base) == LABEL_REF
-	       || (GET_CODE (base) == SYMBOL_REF
-		   && CONSTANT_POOL_ADDRESS_P (base))))
-    return 0;
-
   if (mem_mode == VOIDmode)
     mem_mode = GET_MODE (mem);
 
   x_addr = get_addr (XEXP (x, 0));
   mem_addr = get_addr (XEXP (mem, 0));
 
+  base = find_base_term (x_addr);
+  if (base && (GET_CODE (base) == LABEL_REF
+	       || (GET_CODE (base) == SYMBOL_REF
+		   && CONSTANT_POOL_ADDRESS_P (base))))
+    return 0;
+
   if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
     return 0;
 
@@ -1645,22 +1645,21 @@ write_dependence_p (mem, x, writep)
   /* If MEM is an unchanging read, then it can't possibly conflict with
      the store to X, because there is at most one store to MEM, and it must
      have occurred somewhere before MEM.  */
+  if (! writep && RTX_UNCHANGING_P (mem))
+    return 0;
+
+  x_addr = get_addr (XEXP (x, 0));
+  mem_addr = get_addr (XEXP (mem, 0));
+
   if (! writep)
     {
-      if (RTX_UNCHANGING_P (mem))
-	return 0;
-
-      base = find_base_term (mem);
+      base = find_base_term (mem_addr);
       if (base && (GET_CODE (base) == LABEL_REF
 		   || (GET_CODE (base) == SYMBOL_REF
 		       && CONSTANT_POOL_ADDRESS_P (base))))
 	return 0;
     }
 
-
-  x_addr = get_addr (XEXP (x, 0));
-  mem_addr = get_addr (XEXP (mem, 0));
-
   if (! base_alias_check (x_addr, mem_addr, GET_MODE (x),
 			  GET_MODE (mem)))
     return 0;
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 4898538baa2..4c21a88a4d9 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -427,6 +427,7 @@ static void ix86_emit_restore_regs_using_mov PARAMS ((rtx, int));
 static void ix86_emit_epilogue_esp_adjustment PARAMS((int));
 static void ix86_sched_reorder_pentium PARAMS((rtx *, rtx *));
 static void ix86_sched_reorder_ppro PARAMS((rtx *, rtx *));
+static HOST_WIDE_INT ix86_GOT_alias_set PARAMS ((void));
 
 struct ix86_address
 {
@@ -2553,6 +2554,17 @@ report_error:
   return FALSE;
 }
 
+/* Return an unique alias set for the GOT.  */
+
+static HOST_WIDE_INT   
+ix86_GOT_alias_set ()
+{
+    static HOST_WIDE_INT set = -1;
+    if (set == -1)
+      set = new_alias_set ();
+    return set;
+}   
+
 /* Return a legitimate reference for ORIG (an address) using the
    register REG.  If REG is 0, a new pseudo is generated.
 
@@ -2610,6 +2622,7 @@ legitimize_pic_address (orig, reg)
       new = gen_rtx_PLUS (Pmode, pic_offset_table_rtx, new);
       new = gen_rtx_MEM (Pmode, new);
       RTX_UNCHANGING_P (new) = 1;
+      MEM_ALIAS_SET (new) = ix86_GOT_alias_set ();	
 
       if (reg == 0)
 	reg = gen_reg_rtx (Pmode);
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 5c69a506b55..8424b8e2cde 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -53,7 +53,7 @@ rtx_unstable_p (x)
   register const char *fmt;
 
   if (code == MEM)
-    return ! RTX_UNCHANGING_P (x);
+    return ! RTX_UNCHANGING_P (x) || rtx_unstable_p (XEXP (x, 0));
 
   if (code == QUEUED)
     return 1;
@@ -62,9 +62,9 @@ rtx_unstable_p (x)
     return 0;
 
   if (code == REG)
-    return ! (REGNO (x) == FRAME_POINTER_REGNUM
-	      || REGNO (x) == HARD_FRAME_POINTER_REGNUM
-	      || REGNO (x) == ARG_POINTER_REGNUM
+    /* As in rtx_varies_p, we have to use the actual rtx, not reg number.  */
+    return ! (x == frame_pointer_rtx || x == hard_frame_pointer_rtx
+	      || x == arg_pointer_rtx || x == pic_offset_table_rtx
 	      || RTX_UNCHANGING_P (x));
 
   fmt = GET_RTX_FORMAT (code);
@@ -101,6 +101,8 @@ rtx_varies_p (x)
   switch (code)
     {
     case MEM:
+      return ! RTX_UNCHANGING_P (x) || rtx_varies_p (XEXP (x, 0));
+
     case QUEUED:
       return 1;
 
@@ -174,9 +176,12 @@ rtx_addr_can_trap_p (x)
 
     case PLUS:
       /* An address is assumed not to trap if it is an address that can't
-	 trap plus a constant integer.  */
-      return (rtx_addr_can_trap_p (XEXP (x, 0))
-	      || GET_CODE (XEXP (x, 1)) != CONST_INT);
+	 trap plus a constant integer or it is the pic register plus a
+	 constant.  */
+      return ! ((! rtx_addr_can_trap_p (XEXP (x, 0))
+		 && GET_CODE (XEXP (x, 1)) == CONST_INT)
+		|| (XEXP (x, 0) == pic_offset_table_rtx
+		    && CONSTANT_P (XEXP (x, 1))));
 
     case LO_SUM:
       return rtx_addr_can_trap_p (XEXP (x, 1));