Yoriko Komatsuzaki <yor...@sm.sony.co.jp> writes:
> Could you tell me why it doesn't work well around FRAME_GROWS_DOWNWARD
> on mips ?
I have a WIP patch for this but was holding back mostly because of stage3/4
and that I was trying to make FRAME_GROWS_DOWNWARD the default and I was
running into performance issues.
The patch below enables FRAME_GROWS_DOWNWARD with -mframe-grows-downward
(mostly for testing) and with -fstack-protector.
Adam
Index: config/mips/mips.opt
===================================================================
--- config/mips/mips.opt (revision 142249)
+++ config/mips/mips.opt (working copy)
@@ -283,3 +283,6 @@ Perform VR4130-specific alignment optimi
mxgot
Target Report Var(TARGET_XGOT)
Lift restrictions on GOT size
+
+mframe-grows-downward
+Target Var(flag_frame_grows_downward) Init(1)
Index: config/mips/mips.c
===================================================================
--- config/mips/mips.c (revision 142249)
+++ config/mips/mips.c (working copy)
@@ -274,10 +274,10 @@ struct mips_frame_info GTY(()) {
HOST_WIDE_INT gp_sp_offset;
HOST_WIDE_INT fp_sp_offset;
- /* The offset of arg_pointer_rtx from frame_pointer_rtx. */
+ /* The offset of arg_pointer_rtx from the bottom of the frame. */
HOST_WIDE_INT arg_pointer_offset;
- /* The offset of hard_frame_pointer_rtx from frame_pointer_rtx. */
+ /* The offset of hard_frame_pointer_rtx from the bottom of the frame. */
HOST_WIDE_INT hard_frame_pointer_offset;
};
@@ -8593,10 +8593,9 @@ mips_compute_frame_info (void)
cfun->machine->global_pointer = mips_global_pointer ();
- /* The first STARTING_FRAME_OFFSET bytes contain the outgoing argument
- area and the $gp save slot. This area isn't needed in leaf functions,
- but if the target-independent frame size is nonzero, we're committed
- to allocating it anyway. */
+ /* The first bytes contain the outgoing argument area and the $gp save slot.
+ This area isn't needed in leaf functions, but if the target-independent
+ frame size is nonzero, we're committed to allocating it anyway. */
if (size == 0 && current_function_is_leaf)
{
/* The MIPS 3.0 linker does not like functions that dynamically
@@ -8612,7 +8611,7 @@ mips_compute_frame_info (void)
else
{
frame->args_size = crtl->outgoing_args_size;
- frame->cprestore_size = STARTING_FRAME_OFFSET - frame->args_size;
+ frame->cprestore_size = MIPS_GP_SAVE_AREA_SIZE;
}
offset = frame->args_size + frame->cprestore_size;
@@ -8746,12 +8745,16 @@ mips_initial_elimination_offset (int fro
mips_compute_frame_info ();
- /* Set OFFSET to the offset from the soft frame pointer, which is also
- the offset from the end-of-prologue stack pointer. */
+ /* Set OFFSET to the offset from the end-of-prologue stack pointer. */
switch (from)
{
case FRAME_POINTER_REGNUM:
- offset = 0;
+ if (FRAME_GROWS_DOWNWARD)
+ offset = (cfun->machine->frame.args_size
+ + cfun->machine->frame.cprestore_size
+ + cfun->machine->frame.var_size);
+ else
+ offset = 0;
break;
case ARG_POINTER_REGNUM:
Index: config/mips/mips.h
===================================================================
--- config/mips/mips.h (revision 142249)
+++ config/mips/mips.h (working copy)
@@ -2035,14 +2035,20 @@ enum reg_class
/* Stack layout; function entry, exit and calling. */
+#define FRAME_GROWS_DOWNWARD (flag_frame_grows_downward || flag_stack_protect)
+
#define STACK_GROWS_DOWNWARD
-/* The offset of the first local variable from the beginning of the frame.
- See mips_compute_frame_info for details about the frame layout. */
+#define MIPS_GP_SAVE_AREA_SIZE \
+ (TARGET_CALL_CLOBBERED_GP ? MIPS_STACK_ALIGN (UNITS_PER_WORD) : 0)
+
+/* The offset of the first local variable from the frame pointer. See
+ mips_compute_frame_info for details about the frame layout. */
-#define STARTING_FRAME_OFFSET \
- (crtl->outgoing_args_size \
- + (TARGET_CALL_CLOBBERED_GP ? MIPS_STACK_ALIGN (UNITS_PER_WORD) : 0))
+#define STARTING_FRAME_OFFSET \
+ (FRAME_GROWS_DOWNWARD \
+ ? 0 \
+ : crtl->outgoing_args_size + MIPS_GP_SAVE_AREA_SIZE)
#define RETURN_ADDR_RTX mips_return_addr
