Richard Sandiford <rdsandif...@googlemail.com> writes:
> I'll run a full test overnight, but does this look like it might be
> a way out, at least for 4.9?
FWIW, it passed testing on x86_64-linux-gnu ({,-m32}, all,ada).
Here it is again with an updated cselib.c comment. OK to install?
Thanks,
Richard
gcc/
* builtins.c (expand_builtin_setjmp_receiver): Use and clobber
hard_frame_pointer_rtx.
* cse.c (cse_insn): Remove volatile check.
* cselib.c (cselib_process_insn): Likewise.
* dse.c (scan_insn): Likewise.
Index: gcc/builtins.c
===================================================================
--- gcc/builtins.c 2014-03-03 21:47:59.749026019 +0000
+++ gcc/builtins.c 2014-03-03 21:48:00.550030853 +0000
@@ -910,18 +910,27 @@ expand_builtin_setjmp_receiver (rtx rece
#ifdef HAVE_nonlocal_goto
if (! HAVE_nonlocal_goto)
#endif
- /* First adjust our frame pointer to its actual value. It was
- previously set to the start of the virtual area corresponding to
- the stacked variables when we branched here and now needs to be
- adjusted to the actual hardware fp value.
-
- Assignments to virtual registers are converted by
- instantiate_virtual_regs into the corresponding assignment
- to the underlying register (fp in this case) that makes
- the original assignment true.
- So the following insn will actually be decrementing fp by
- STARTING_FRAME_OFFSET. */
- emit_move_insn (virtual_stack_vars_rtx, hard_frame_pointer_rtx);
+ {
+ /* First adjust our frame pointer to its actual value. It was
+ previously set to the start of the virtual area corresponding to
+ the stacked variables when we branched here and now needs to be
+ adjusted to the actual hardware fp value.
+
+ Assignments to virtual registers are converted by
+ instantiate_virtual_regs into the corresponding assignment
+ to the underlying register (fp in this case) that makes
+ the original assignment true.
+ So the following insn will actually be decrementing fp by
+ STARTING_FRAME_OFFSET. */
+ emit_move_insn (virtual_stack_vars_rtx, hard_frame_pointer_rtx);
+
+ /* Restoring the frame pointer also modifies the hard frame pointer.
+ Mark it used (so that the previous assignment remains live once
+ the frame pointer is eliminated) and clobbered (to represent the
+ implicit update from the assignment). */
+ emit_use (hard_frame_pointer_rtx);
+ emit_clobber (hard_frame_pointer_rtx);
+ }
#if !HARD_FRAME_POINTER_IS_ARG_POINTER
if (fixed_regs[ARG_POINTER_REGNUM])
@@ -965,8 +974,7 @@ expand_builtin_setjmp_receiver (rtx rece
/* We must not allow the code we just generated to be reordered by
scheduling. Specifically, the update of the frame pointer must
- happen immediately, not later. Similarly, we must block
- (frame-related) register values to be used across this code. */
+ happen immediately, not later. */
emit_insn (gen_blockage ());
}
Index: gcc/cse.c
===================================================================
--- gcc/cse.c 2014-03-03 21:47:59.869026741 +0000
+++ gcc/cse.c 2014-03-03 21:48:00.625031305 +0000
@@ -5664,11 +5664,6 @@ cse_insn (rtx insn)
invalidate (XEXP (dest, 0), GET_MODE (dest));
}
- /* A volatile ASM or an UNSPEC_VOLATILE invalidates everything. */
- if (NONJUMP_INSN_P (insn)
- && volatile_insn_p (PATTERN (insn)))
- flush_hash_table ();
-
/* Don't cse over a call to setjmp; on some machines (eg VAX)
the regs restored by the longjmp come from a later time
than the setjmp. */
Index: gcc/cselib.c
===================================================================
--- gcc/cselib.c 2014-03-03 21:47:59.870026748 +0000
+++ gcc/cselib.c 2014-03-03 22:09:24.211994918 +0000
@@ -2626,12 +2626,10 @@ cselib_process_insn (rtx insn)
cselib_current_insn = insn;
- /* Forget everything at a CODE_LABEL, a volatile insn, or a setjmp. */
+ /* Forget everything at a CODE_LABEL or a setjmp. */
if ((LABEL_P (insn)
|| (CALL_P (insn)
- && find_reg_note (insn, REG_SETJMP, NULL))
- || (NONJUMP_INSN_P (insn)
- && volatile_insn_p (PATTERN (insn))))
+ && find_reg_note (insn, REG_SETJMP, NULL)))
&& !cselib_preserve_constants)
{
cselib_reset_table (next_uid);
Index: gcc/dse.c
===================================================================
--- gcc/dse.c 2014-03-03 21:47:59.871026754 +0000
+++ gcc/dse.c 2014-03-03 21:48:00.627031317 +0000
@@ -2470,16 +2470,6 @@ scan_insn (bb_info_t bb_info, rtx insn)
return;
}
- /* Cselib clears the table for this case, so we have to essentially
- do the same. */
- if (NONJUMP_INSN_P (insn)
- && volatile_insn_p (PATTERN (insn)))
- {
- add_wild_read (bb_info);
- insn_info->cannot_delete = true;
- return;
- }
-
/* Look at all of the uses in the insn. */
note_uses (&PATTERN (insn), check_mem_read_use, bb_info);
