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Simplify streaming of SCC components 

this patch saves few bytes from SCC streaming.  First we stream end markers
that are fully ignored at stream in.
Second I missed streaming of emtry_len in the previous change so it is
pointlessly streamed for LTO_trees. Moreover entry_len is almost always 1
(always during gcc bootstrap) and thus it makes sense to avoid stremaing it
in majority of cases.

gcc/ChangeLog:

2020-05-21  Jan Hubicka  <hubicka@ucw.cz>

	* lto-streamer-in.c (lto_read_tree): Do not stream end markers.
	(lto_input_scc): Optimize streaming of entry lengths.
	* lto-streamer-out.c (lto_write_tree): Do not stream end markers
	(DFS::DFS): Optimize stremaing of entry lengths
This commit is contained in:
Jan Hubicka 2020-05-22 12:29:19 +02:00
parent ab7eca9292
commit 47273df0bc
3 changed files with 23 additions and 20 deletions
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7
gcc/ChangeLog
View File

@ -1,3 +1,10 @@
2020-05-22 Jan Hubicka <hubicka@ucw.cz>
* lto-streamer-in.c (lto_read_tree): Do not stream end markers.
(lto_input_scc): Optimize streaming of entry lengths.
* lto-streamer-out.c (lto_write_tree): Do not stream end markers
(DFS::DFS): Optimize stremaing of entry lengths
2020-05-22 Richard Biener <rguenther@suse.de>
PR lto/95190

17
gcc/lto-streamer-in.c
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@ -1417,8 +1417,6 @@ lto_read_tree (class lto_input_block *ib, class data_in *data_in,
lto_read_tree_1 (ib, data_in, result);
/* end_marker = */ streamer_read_uchar (ib);
return result;
}
@ -1431,12 +1429,18 @@ hashval_t
lto_input_scc (class lto_input_block *ib, class data_in *data_in,
unsigned *len, unsigned *entry_len, bool shared_scc)
{
/* A blob of unnamed tree nodes, fill the cache from it and
recurse. */
unsigned size = streamer_read_uhwi (ib);
hashval_t scc_hash = shared_scc ? streamer_read_uhwi (ib) : 0;
hashval_t scc_hash = 0;
unsigned scc_entry_len = 1;
if (shared_scc)
{
if (size & 1)
scc_entry_len = streamer_read_uhwi (ib);
size /= 2;
scc_hash = streamer_read_uhwi (ib);
}
if (size == 1)
{
enum LTO_tags tag = streamer_read_record_start (ib);
@ -1447,8 +1451,6 @@ lto_input_scc (class lto_input_block *ib, class data_in *data_in,
unsigned int first = data_in->reader_cache->nodes.length ();
tree result;
scc_entry_len = streamer_read_uhwi (ib);
/* Materialize size trees by reading their headers. */
for (unsigned i = 0; i < size; ++i)
{
@ -1471,7 +1473,6 @@ lto_input_scc (class lto_input_block *ib, class data_in *data_in,
result = streamer_tree_cache_get_tree (data_in->reader_cache,
first + i);
lto_read_tree_1 (ib, data_in, result);
/* end_marker = */ streamer_read_uchar (ib);
}
}

19
gcc/lto-streamer-out.c
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@ -473,9 +473,6 @@ lto_write_tree (struct output_block *ob, tree expr, bool ref_p)
streamer_write_tree_header (ob, expr);
lto_write_tree_1 (ob, expr, ref_p);
/* Mark the end of EXPR. */
streamer_write_zero (ob);
}
/* Emit the physical representation of tree node EXPR to output block OB,
@ -764,7 +761,12 @@ DFS::DFS (struct output_block *ob, tree expr, bool ref_p, bool this_ref_p,
{
gcc_checking_assert (ob->section_type == LTO_section_decls);
streamer_write_record_start (ob, LTO_tree_scc);
streamer_write_uhwi (ob, size);
/* In wast majority of cases scc_entry_len is 1 and size is small
integer. Use extra bit of size to stream info about
exceptions. */
streamer_write_uhwi (ob, size * 2 + (scc_entry_len != 1));
if (scc_entry_len != 1)
streamer_write_uhwi (ob, scc_entry_len);
streamer_write_uhwi (ob, scc_hash);
}
/* Non-trivial SCCs must be packed to trees blocks so forward
@ -783,8 +785,6 @@ DFS::DFS (struct output_block *ob, tree expr, bool ref_p, bool this_ref_p,
lto_output_tree_1 (ob, expr, scc_hash, ref_p, this_ref_p);
else
{
/* Write the size of the SCC entry candidates. */
streamer_write_uhwi (ob, scc_entry_len);
/* Write all headers and populate the streamer cache. */
for (unsigned i = 0; i < size; ++i)
@ -807,12 +807,7 @@ DFS::DFS (struct output_block *ob, tree expr, bool ref_p, bool this_ref_p,
/* Write the bitpacks and tree references. */
for (unsigned i = 0; i < size; ++i)
{
lto_write_tree_1 (ob, sccstack[first+i].t, ref_p);
/* Mark the end of the tree. */
streamer_write_zero (ob);
}
lto_write_tree_1 (ob, sccstack[first+i].t, ref_p);
}
/* Finally truncate the vector. */