Skip to content

R
riscv-gcc-1
Commit 64274683 by Paolo Bonzini Committed by Paolo Bonzini
Options

df-problems.c: Fix documentation for forward simulation of LR. 

2009-11-08  Paolo Bonzini  <bonzini@gnu.org>

	* df-problems.c: Fix documentation for forward simulation of LR.
	(df_simulate_one_insn_forwards): Use df_simulate_find_defs.
	(df_simulate_finalize_forwards): Remove.
	* df.h (df_simulate_finalize_forwards): Remove.

From-SVN: r154012
parent 379c6f48
Showing with 29 additions and 31 deletions
gcc/ChangeLog
2009-11-08 Paolo Bonzini <bonzini@gnu.org>
* df-problems.c: Fix documentation for forward simulation of LR.
(df_simulate_one_insn_forwards): Use df_simulate_find_defs.
(df_simulate_finalize_forwards): Remove.
* df.h (df_simulate_finalize_forwards): Remove.
2009-11-08 Richard Guenther <rguenther@suse.de>
* tree-ssa-structalias.c (build_succ_graph): Properly make
gcc/df-problems.c
......@@ -3722,9 +3722,11 @@ df_note_add_problem (void)
You can either simulate in the forwards direction, starting from
the top of a block or the backwards direction from the end of the
block. The main difference is that if you go forwards, the uses
are examined first then the defs, and if you go backwards, the defs
are examined first then the uses.
block. If you go backwards, defs are examined first to clear bits,
then uses are examined to set bits. If you go forwards, defs are
examined first to set bits, then REG_DEAD and REG_UNUSED notes
are examined to clear bits. In either case, the result of examining
a def can be undone (respectively by a use or a REG_UNUSED note).
If you start at the top of the block, use one of DF_LIVE_IN or
DF_LR_IN. If you start at the bottom of the block use one of
......@@ -3814,7 +3816,7 @@ df_simulate_fixup_sets (basic_block bb, bitmap live)
df_simulate_initialize_backwards should be called first with a
bitvector copyied from the DF_LIVE_OUT or DF_LR_OUT. Then
df_simulate_one_insn_backwards should be called for each insn in
the block, starting with the last on. Finally,
the block, starting with the last one. Finally,
df_simulate_finalize_backwards can be called to get a new value
of the sets at the top of the block (this is rarely used).
----------------------------------------------------------------------------*/
......@@ -3896,13 +3898,16 @@ df_simulate_finalize_backwards (basic_block bb, bitmap live)
df_simulate_initialize_forwards should be called first with a
bitvector copyied from the DF_LIVE_IN or DF_LR_IN. Then
df_simulate_one_insn_forwards should be called for each insn in
the block, starting with the last on. Finally,
df_simulate_finalize_forwards can be called to get a new value
of the sets at the bottom of the block (this is rarely used).
the block, starting with the first one.
----------------------------------------------------------------------------*/
/* Apply the artificial uses and defs at the top of BB in a backwards
direction. */
/* Apply the artificial uses and defs at the top of BB in a forwards
direction. ??? This is wrong; defs mark the point where a pseudo
becomes live when scanning forwards (unless a def is unused). Since
there are no REG_UNUSED notes for artificial defs, passes that
require artificial defs probably should not call this function
unless (as is the case for fwprop) they are correct when liveness
bitmaps are *under*estimated. */
void
df_simulate_initialize_forwards (basic_block bb, bitmap live)
......@@ -3918,7 +3923,7 @@ df_simulate_initialize_forwards (basic_block bb, bitmap live)
}
}
/* Simulate the backwards effects of INSN on the bitmap LIVE. */
/* Simulate the forwards effects of INSN on the bitmap LIVE. */
void
df_simulate_one_insn_forwards (basic_block bb, rtx insn, bitmap live)
......@@ -3927,10 +3932,15 @@ df_simulate_one_insn_forwards (basic_block bb, rtx insn, bitmap live)
if (! INSN_P (insn))
return;
/* Make sure that the DF_NOTES really is an active df problem. */
/* Make sure that DF_NOTE really is an active df problem. */
gcc_assert (df_note);
df_simulate_defs (insn, live);
/* Note that this is the opposite as how the problem is defined, because
in the LR problem defs _kill_ liveness. However, they do so backwards,
while here the scan is performed forwards! So, first assume that the
def is live, and if this is not true REG_UNUSED notes will rectify the
situation. */
df_simulate_find_defs (insn, live);
/* Clear all of the registers that go dead. */
for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
......@@ -3960,24 +3970,6 @@ df_simulate_one_insn_forwards (basic_block bb, rtx insn, bitmap live)
}
/* Apply the artificial uses and defs at the end of BB in a backwards
direction. */
void
df_simulate_finalize_forwards (basic_block bb, bitmap live)
{
df_ref *def_rec;
int bb_index = bb->index;
for (def_rec = df_get_artificial_defs (bb_index); *def_rec; def_rec++)
{
df_ref def = *def_rec;
if ((DF_REF_FLAGS (def) & DF_REF_AT_TOP) == 0)
bitmap_clear_bit (live, DF_REF_REGNO (def));
}
}
/*----------------------------------------------------------------------------
MULTIPLE DEFINITIONS
......
gcc/df.h
......@@ -985,7 +985,6 @@ extern void df_simulate_one_insn_backwards (basic_block, rtx, bitmap);
extern void df_simulate_finalize_backwards (basic_block, bitmap);
extern void df_simulate_initialize_forwards (basic_block, bitmap);
extern void df_simulate_one_insn_forwards (basic_block, rtx, bitmap);
extern void df_simulate_finalize_forwards (basic_block, bitmap);
/* Functions defined in df-scan.c. */
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment