*_ALIGN_MAX_SKIP macros
DJ Delorie
dj@redhat.com
Wed Oct 6 00:34:00 GMT 2010
> DJ Delorie <dj@redhat.com> writes:
> > JUMP_ALIGN_MAX_SKIP
> > LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP
> > LOOP_ALIGN_MAX_SKIP
> > LABEL_ALIGN_MAX_SKIP
> >
> > None of these macros take any parameters, but for optimal performance
> > on RX, it's key to match the max_skip with the size of the following
> > opcode - there's a penalty only if you branch to an opcode which spans
> > fetch groups, but it's the same penalty as running a NOP opcode, so
> > you don't want to add nops if you don't have to.
> >
> > Can we extend those macros to take the label as a parameter? From
> > that, the backend could find the next actual insn.
>
> Seems fine to me. Looks like none of the existing targets define them
> directly anyhow.
>
> If you do this, though, turn them into target hooks. They are currently
> fields in target_flag_state.
How's this?
* doc/tm.texi.in (TARGET_ASM_JUMP_ALIGN_MAX_SKIP): New.
(TARGET_ASM_LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP): Change to hook.
(TARGET_ASM_LOOP_ALIGN_MAX_SKIP): Likewise.
(TARGET_ASM_LABEL_ALIGN_MAX_SKIP): Likewise.
* targhooks.h (default_label_align_after_barrier_max_skip,
default_loop_align_max_skip, default_label_align_max_skip,
default_jump_align_max_skip): Declare.
* target.def (label_align_after_barrier_max_skip): New.
(loop_align_max_skip): New.
(label_align_max_skip): New.
(jump_align_max_skip): New.
* final.c (LABEL_ALIGN_MAX_SKIP): Remove.
(LOOP_ALIGN_MAX_SKIP): Remove.
(LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP): Remove.
(JUMP_ALIGN_MAX_SKIP): Remove.
(default_label_align_after_barrier_max_skip): New.
(default_loop_align_max_skip): New.
(default_label_align_max_skip): New.
(default_jump_align_max_skip): New.
(compute_alignments): Use the new hooks.
(shorten_branches): Likewise.
Index: doc/tm.texi.in
===================================================================
--- doc/tm.texi.in (revision 164701)
+++ doc/tm.texi.in (working copy)
@@ -8893,26 +8893,32 @@ define the macro.
Unless it's necessary to inspect the @var{label} parameter, it is better
to set the variable @var{align_jumps} in the target's
@code{TARGET_OPTION_OVERRIDE}. Otherwise, you should try to honor the user's
selection in @var{align_jumps} in a @code{JUMP_ALIGN} implementation.
@end defmac
+@hook TARGET_ASM_JUMP_ALIGN_MAX_SKIP
+The maximum number of bytes to skip before @var{label} when applying
+@code{JUMP_ALIGN}. This works only if
+@code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.
+@end deftypefn
+
@defmac LABEL_ALIGN_AFTER_BARRIER (@var{label})
The alignment (log base 2) to put in front of @var{label}, which follows
a @code{BARRIER}.
This macro need not be defined if you don't want any special alignment
to be done at such a time. Most machine descriptions do not currently
define the macro.
@end defmac
-@defmac LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP
-The maximum number of bytes to skip when applying
+@hook TARGET_ASM_LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP
+The maximum number of bytes to skip before @var{label} when applying
@code{LABEL_ALIGN_AFTER_BARRIER}. This works only if
@code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.
-@end defmac
+@end deftypefn
@defmac LOOP_ALIGN (@var{label})
The alignment (log base 2) to put in front of @var{label}, which follows
a @code{NOTE_INSN_LOOP_BEG} note.
This macro need not be defined if you don't want any special alignment
@@ -8922,32 +8928,34 @@ define the macro.
Unless it's necessary to inspect the @var{label} parameter, it is better
to set the variable @code{align_loops} in the target's
@code{TARGET_OPTION_OVERRIDE}. Otherwise, you should try to honor the user's
selection in @code{align_loops} in a @code{LOOP_ALIGN} implementation.
@end defmac
-@defmac LOOP_ALIGN_MAX_SKIP
-The maximum number of bytes to skip when applying @code{LOOP_ALIGN}.
-This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.
-@end defmac
+@hook TARGET_ASM_LOOP_ALIGN_MAX_SKIP
+The maximum number of bytes to skip when applying @code{LOOP_ALIGN} to
+@var{label}. This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN} is
+defined.
+@end deftypefn
@defmac LABEL_ALIGN (@var{label})
The alignment (log base 2) to put in front of @var{label}.
If @code{LABEL_ALIGN_AFTER_BARRIER} / @code{LOOP_ALIGN} specify a different alignment,
the maximum of the specified values is used.
Unless it's necessary to inspect the @var{label} parameter, it is better
to set the variable @code{align_labels} in the target's
@code{TARGET_OPTION_OVERRIDE}. Otherwise, you should try to honor the user's
selection in @code{align_labels} in a @code{LABEL_ALIGN} implementation.
@end defmac
-@defmac LABEL_ALIGN_MAX_SKIP
-The maximum number of bytes to skip when applying @code{LABEL_ALIGN}.
-This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.
-@end defmac
+@hook TARGET_ASM_LABEL_ALIGN_MAX_SKIP
+The maximum number of bytes to skip when applying @code{LABEL_ALIGN}
+to @var{label}. This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN}
+is defined.
+@end deftypefn
@defmac ASM_OUTPUT_SKIP (@var{stream}, @var{nbytes})
A C statement to output to the stdio stream @var{stream} an assembler
instruction to advance the location counter by @var{nbytes} bytes.
Those bytes should be zero when loaded. @var{nbytes} will be a C
expression of type @code{unsigned HOST_WIDE_INT}.
Index: targhooks.h
===================================================================
--- targhooks.h (revision 164701)
+++ targhooks.h (working copy)
@@ -156,6 +156,11 @@ extern bool default_profile_before_prolo
extern bool default_class_likely_spilled_p (reg_class_t);
extern enum unwind_info_type default_debug_unwind_info (void);
extern enum unwind_info_type default_except_unwind_info (void);
extern enum unwind_info_type dwarf2_except_unwind_info (void);
extern enum unwind_info_type sjlj_except_unwind_info (void);
+
+extern int default_label_align_after_barrier_max_skip (rtx);
+extern int default_loop_align_max_skip (rtx);
+extern int default_label_align_max_skip (rtx);
+extern int default_jump_align_max_skip (rtx);
Index: target.def
===================================================================
--- target.def (revision 164701)
+++ target.def (working copy)
@@ -98,12 +98,44 @@ DEFHOOKPOD
(byte_op,
"",
const char *, "\t.byte\t")
DEFHOOKPOD (aligned_op, "*", struct asm_int_op, TARGET_ASM_ALIGNED_INT_OP)
DEFHOOKPOD (unaligned_op, "*", struct asm_int_op, TARGET_ASM_UNALIGNED_INT_OP)
+/* The maximum number of bytes to skip when applying
+ LABEL_ALIGN_AFTER_BARRIER. */
+DEFHOOK
+(label_align_after_barrier_max_skip,
+ "",
+ int, (rtx label),
+ default_label_align_after_barrier_max_skip)
+
+/* The maximum number of bytes to skip when applying
+ LOOP_ALIGN. */
+DEFHOOK
+(loop_align_max_skip,
+ "",
+ int, (rtx label),
+ default_loop_align_max_skip)
+
+/* The maximum number of bytes to skip when applying
+ LABEL_ALIGN. */
+DEFHOOK
+(label_align_max_skip,
+ "",
+ int, (rtx label),
+ default_label_align_max_skip)
+
+/* The maximum number of bytes to skip when applying
+ JUMP_ALIGN. */
+DEFHOOK
+(jump_align_max_skip,
+ "",
+ int, (rtx label),
+ default_jump_align_max_skip)
+
/* Try to output the assembler code for an integer object whose
value is given by X. SIZE is the size of the object in bytes and
ALIGNED_P indicates whether it is aligned. Return true if
successful. Only handles cases for which BYTE_OP, ALIGNED_OP
and UNALIGNED_OP are NULL. */
DEFHOOK
Index: final.c
===================================================================
--- final.c (revision 164701)
+++ final.c (working copy)
@@ -65,12 +65,13 @@ along with GCC; see the file COPYING3.
#include "rtl-error.h"
#include "toplev.h" /* exact_log2, floor_log2 */
#include "reload.h"
#include "intl.h"
#include "basic-block.h"
#include "target.h"
+#include "targhooks.h"
#include "debug.h"
#include "expr.h"
#include "cfglayout.h"
#include "tree-pass.h"
#include "tree-flow.h"
#include "timevar.h"
@@ -494,39 +495,47 @@ get_attr_min_length (rtx insn)
address mod X to one mod Y, which is Y - X. */
#ifndef LABEL_ALIGN
#define LABEL_ALIGN(LABEL) align_labels_log
#endif
-#ifndef LABEL_ALIGN_MAX_SKIP
-#define LABEL_ALIGN_MAX_SKIP align_labels_max_skip
-#endif
-
#ifndef LOOP_ALIGN
#define LOOP_ALIGN(LABEL) align_loops_log
#endif
-#ifndef LOOP_ALIGN_MAX_SKIP
-#define LOOP_ALIGN_MAX_SKIP align_loops_max_skip
-#endif
-
#ifndef LABEL_ALIGN_AFTER_BARRIER
#define LABEL_ALIGN_AFTER_BARRIER(LABEL) 0
#endif
-#ifndef LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP
-#define LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP 0
-#endif
-
#ifndef JUMP_ALIGN
#define JUMP_ALIGN(LABEL) align_jumps_log
#endif
-#ifndef JUMP_ALIGN_MAX_SKIP
-#define JUMP_ALIGN_MAX_SKIP align_jumps_max_skip
-#endif
+int
+default_label_align_after_barrier_max_skip (rtx insn ATTRIBUTE_UNUSED)
+{
+ return 0;
+}
+
+int
+default_loop_align_max_skip (rtx insn ATTRIBUTE_UNUSED)
+{
+ return align_loops_max_skip;
+}
+
+int
+default_label_align_max_skip (rtx insn ATTRIBUTE_UNUSED)
+{
+ return align_labels_max_skip;
+}
+
+int
+default_jump_align_max_skip (rtx insn ATTRIBUTE_UNUSED)
+{
+ return align_jumps_max_skip;
+}
#ifndef ADDR_VEC_ALIGN
static int
final_addr_vec_align (rtx addr_vec)
{
int align = GET_MODE_SIZE (GET_MODE (PATTERN (addr_vec)));
@@ -728,13 +737,13 @@ compute_alignments (void)
if (dump_file)
fprintf(dump_file, "BB %4i freq %4i loop %2i loop_depth %2i skipped.\n",
bb->index, bb->frequency, bb->loop_father->num, bb->loop_depth);
continue;
}
max_log = LABEL_ALIGN (label);
- max_skip = LABEL_ALIGN_MAX_SKIP;
+ max_skip = targetm.asm_out.label_align_max_skip (label);
FOR_EACH_EDGE (e, ei, bb->preds)
{
if (e->flags & EDGE_FALLTHRU)
has_fallthru = 1, fallthru_frequency += EDGE_FREQUENCY (e);
else
@@ -772,13 +781,13 @@ compute_alignments (void)
log = JUMP_ALIGN (label);
if (dump_file)
fprintf(dump_file, " jump alignment added.\n");
if (max_log < log)
{
max_log = log;
- max_skip = JUMP_ALIGN_MAX_SKIP;
+ max_skip = targetm.asm_out.jump_align_max_skip (label);
}
}
/* In case block is frequent and reached mostly by non-fallthru edge,
align it. It is most likely a first block of loop. */
if (has_fallthru
&& optimize_bb_for_speed_p (bb)
@@ -789,13 +798,13 @@ compute_alignments (void)
log = LOOP_ALIGN (label);
if (dump_file)
fprintf(dump_file, " internal loop alignment added.\n");
if (max_log < log)
{
max_log = log;
- max_skip = LOOP_ALIGN_MAX_SKIP;
+ max_skip = targetm.asm_out.loop_align_max_skip (label);
}
}
LABEL_TO_ALIGNMENT (label) = max_log;
LABEL_TO_MAX_SKIP (label) = max_skip;
}
@@ -922,26 +931,26 @@ shorten_branches (rtx first ATTRIBUTE_UN
if (!next_is_jumptable)
{
log = LABEL_ALIGN (insn);
if (max_log < log)
{
max_log = log;
- max_skip = LABEL_ALIGN_MAX_SKIP;
+ max_skip = targetm.asm_out.label_align_max_skip (insn);
}
}
/* ADDR_VECs only take room if read-only data goes into the text
section. */
if ((JUMP_TABLES_IN_TEXT_SECTION
|| readonly_data_section == text_section)
&& next_is_jumptable)
{
log = ADDR_VEC_ALIGN (next);
if (max_log < log)
{
max_log = log;
- max_skip = LABEL_ALIGN_MAX_SKIP;
+ max_skip = targetm.asm_out.label_align_max_skip (insn);
}
}
LABEL_TO_ALIGNMENT (insn) = max_log;
LABEL_TO_MAX_SKIP (insn) = max_skip;
max_log = 0;
max_skip = 0;
@@ -955,13 +964,13 @@ shorten_branches (rtx first ATTRIBUTE_UN
if (LABEL_P (label))
{
log = LABEL_ALIGN_AFTER_BARRIER (insn);
if (max_log < log)
{
max_log = log;
- max_skip = LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP;
+ max_skip = targetm.asm_out.label_align_after_barrier_max_skip (label);
}
break;
}
}
}
#ifdef HAVE_ATTR_length
More information about the Gcc
mailing list