On Wed, Mar 21, 2012 at 1:13 AM, Ian Lance Taylor wrote:
> On Tue, Mar 20, 2012 at 2:06 PM, Steven Bosscher wrote:
>>
>> This patch splits a couple of pieces of cse_insn out to new functions.
>> There are no functional changes, and no code generation differences as
>> far as I could tell on x86_64 (-m64 and -m32).
Likewise for the attached patch.
>> The purpose of the patch is and, loto hopefully make cse_insn easier
>> to understand. In a follow-up patch, I will make canonicalize_insn run
>> only once per insn (it currently, i.e. before and after this patch,
>> runs multiple times for CSE on extended basic blocks if a block is in
>> multiple extended basic blocks).
That is what the attached patch does.
Bootstrapped&tested on x86_64-unknown-linux-gnu.
OK for trunk?
Ciao!
Steven
* cse.c (cse_canonicalized_basic_blocks): New simple bitmap to
tag basic blocks that have already been traversed at least once,
so that all insns have been canonicalized.
(cse_insn): Call canonicalize_insn only if the basic block that
contains insn is visited for the first time.
(cse_extended_basic_block): After visiting all insns in a basic
block, mark the block in cse_canonicalized_basic_blocks.
(cse_main): Setup and destroy cse_canonicalized_basic_blocks.
(cse_find_path): Micro-optimization, reorder one condition to
avoid a reference to cfun.
* cse.c (cse_canonicalized_basic_blocks): New simple bitmap to
tag basic blocks that have already been traversed at least once,
so that all insns have been canonicalized.
(cse_insn): Call canonicalize_insn only if the basic block that
contains insn is visited for the first time.
(cse_extended_basic_block): After visiting all insns in a basic
block, mark the block in cse_canonicalized_basic_blocks.
(cse_main): Setup and destroy cse_canonicalized_basic_blocks.
(cse_find_path): Micro-optimization, reorder one condition to
avoid a reference to cfun.
Index: cse.c
===================================================================
--- cse.c (revision 185622)
+++ cse.c (working copy)
@@ -551,6 +551,10 @@ static bitmap cse_ebb_live_in, cse_ebb_l
already as part of an already processed extended basic block. */
static sbitmap cse_visited_basic_blocks;
+/* A simple bitmap to track for which basic blocks all insns have been
+ canonicalized already. */
+static sbitmap cse_canonicalized_basic_blocks;
+
static bool fixed_base_plus_p (rtx x);
static int notreg_cost (rtx, enum rtx_code, int);
static int approx_reg_cost_1 (rtx *, void *);
@@ -4492,8 +4496,10 @@ cse_insn (rtx insn)
/* Record all the SETs in this instruction. */
n_sets = find_sets_in_insn (insn, &sets);
- /* Substitute the canonical register where possible. */
- canonicalize_insn (insn, &sets, n_sets);
+ /* If we have not visited this block before (as part of another extended
+ basic block, substitute the canonical register where possible. */
+ if (!TEST_BIT (cse_canonicalized_basic_blocks, BLOCK_FOR_INSN (insn)->index))
+ canonicalize_insn (insn, &sets, n_sets);
/* If this insn has a REG_EQUAL note, store the equivalent value in SRC_EQV,
if different, or if the DEST is a STRICT_LOW_PART. The latter condition
@@ -6254,10 +6260,9 @@ cse_find_path (basic_block first_bb, str
else
e = NULL;
- if (e
- && !((e->flags & EDGE_ABNORMAL_CALL) && cfun->has_nonlocal_label)
- && e->dest != EXIT_BLOCK_PTR
+ if (e && e->dest != EXIT_BLOCK_PTR
&& single_pred_p (e->dest)
+ && !((e->flags & EDGE_ABNORMAL_CALL) && cfun->has_nonlocal_label)
/* Avoid visiting basic blocks twice. The large comment
above explains why this can happen. */
&& !TEST_BIT (cse_visited_basic_blocks, e->dest->index))
@@ -6452,6 +6457,9 @@ cse_extended_basic_block (struct cse_bas
}
}
+ /* We have now canonicalized all insns in this basic block. */
+ SET_BIT (cse_canonicalized_basic_blocks, bb->index);
+
/* With non-call exceptions, we are not always able to update
the CFG properly inside cse_insn. So clean up possibly
redundant EH edges here. */
@@ -6555,6 +6563,10 @@ cse_main (rtx f ATTRIBUTE_UNUSED, int nr
cse_visited_basic_blocks = sbitmap_alloc (last_basic_block);
sbitmap_zero (cse_visited_basic_blocks);
+ /* Set up the table of already canonicalized basic blocks. */
+ cse_canonicalized_basic_blocks = sbitmap_alloc (last_basic_block);
+ sbitmap_zero (cse_canonicalized_basic_blocks);
+
/* Loop over basic blocks in reverse completion order (RPO),
excluding the ENTRY and EXIT blocks. */
n_blocks = pre_and_rev_post_order_compute (NULL, rc_order, false);
@@ -6598,6 +6610,7 @@ cse_main (rtx f ATTRIBUTE_UNUSED, int nr
free (reg_eqv_table);
free (ebb_data.path);
sbitmap_free (cse_visited_basic_blocks);
+ sbitmap_free (cse_canonicalized_basic_blocks);
free (rc_order);
rtl_hooks = general_rtl_hooks;
