Merge trunk into svelinaro-dev/sve

1 files changed, 11 insertions, 28 deletions

diff --git a/gcc/cselib.c b/gcc/cselib.c
index 9c8f206c909..c491bded100 100644
--- a/gcc/cselib.c
+++ b/gcc/cselib.c
@@ -1440,15 +1440,8 @@ expand_loc (struct elt_loc_list *p, struct expand_value_data *evd,
 
   for (; p; p = p->next)
     {
-      /* Return these right away to avoid returning stack pointer based
-	 expressions for frame pointer and vice versa, which is something
-	 that would confuse DSE.  See the comment in cselib_expand_value_rtx_1
-	 for more details.  */
       if (REG_P (p->loc)
-	  && (REGNO (p->loc) == STACK_POINTER_REGNUM
-	      || REGNO (p->loc) == FRAME_POINTER_REGNUM
-	      || REGNO (p->loc) == HARD_FRAME_POINTER_REGNUM
-	      || REGNO (p->loc) == cfa_base_preserved_regno))
+	  && REGNO (p->loc) == cfa_base_preserved_regno)
 	return p->loc;
       /* Avoid infinite recursion trying to expand a reg into a
 	 the same reg.  */
@@ -1614,26 +1607,7 @@ cselib_expand_value_rtx_1 (rtx orig, struct expand_value_data *evd,
 	      rtx result;
 	      unsigned regno = REGNO (orig);
 
-	      /* The only thing that we are not willing to do (this
-		 is requirement of dse and if others potential uses
-		 need this function we should add a parm to control
-		 it) is that we will not substitute the
-		 STACK_POINTER_REGNUM, FRAME_POINTER or the
-		 HARD_FRAME_POINTER.
-
-		 These expansions confuses the code that notices that
-		 stores into the frame go dead at the end of the
-		 function and that the frame is not effected by calls
-		 to subroutines.  If you allow the
-		 STACK_POINTER_REGNUM substitution, then dse will
-		 think that parameter pushing also goes dead which is
-		 wrong.  If you allow the FRAME_POINTER or the
-		 HARD_FRAME_POINTER then you lose the opportunity to
-		 make the frame assumptions.  */
-	      if (regno == STACK_POINTER_REGNUM
-		  || regno == FRAME_POINTER_REGNUM
-		  || regno == HARD_FRAME_POINTER_REGNUM
-		  || regno == cfa_base_preserved_regno)
+	      if (regno == cfa_base_preserved_regno)
 		return orig;
 
 	      bitmap_set_bit (evd->regs_active, regno);
@@ -2389,6 +2363,15 @@ cselib_record_set (rtx dest, cselib_val *src_elt, cselib_val *dest_addr_elt)
 
   if (REG_P (dest))
     {
+      /* Do not record equivalences for the frame pointer, since that is
+	 ultimately set from the stack pointer.  We need to maintain
+	 the invariant (relied on by alias.c) that references to a given
+	 region of the stack consistently use the frame pointer or
+	 consistently use the stack pointer; we cannot mix the two.  */
+      if (dest == hard_frame_pointer_rtx
+	  || dest == frame_pointer_rtx)
+	return;
+
       unsigned int dreg = REGNO (dest);
       if (dreg < FIRST_PSEUDO_REGISTER)
 	{