[PATCH] options, lto: Optimize streaming of optimization nodes

[PATCH] options, lto: Optimize streaming of optimization nodes

[Jakub Jelinek]

Hi!

When working on the previous patch, I've noticed that all cl_optimization
fields appart from strings are streamed with bp_pack_value (..., 64); so we
waste quite a lot of space, given that many of the options are just booleans
or char options and there are 450-ish of them.

Fixed by streaming the number of bits the corresponding fields have.
While for char fields we have also range information, except for 3
it is either -128, 127 or 0, 255, so it didn't seem worth it to bother
with using range-ish packing.

Bootstrapped/regtested on x86_64-linux, i686-linux, armv7hl-linux-gnueabi,
aarch64-linux, powerpc64le-linux and lto bootstrapped on x86_64-linux, ok
for trunk?

2020-09-13  Jakub Jelinek  <jakub@redhat.com>

	* optc-save-gen.awk: In cl_optimization_stream_out and
	cl_optimization_stream_in, stream int, enum, short and char
	variables with corresponding HOST_BITS_PER_* rather than
	hardcoded 64.

--- gcc/optc-save-gen.awk.jj	2020-09-11 17:38:31.524230167 +0200
+++ gcc/optc-save-gen.awk	2020-09-11 22:12:59.948580827 +0200
@@ -1252,13 +1252,23 @@ print "cl_optimization_stream_out (struc
 print "                            struct bitpack_d *bp,";
 print "                            struct cl_optimization *ptr)";
 print "{";
-for (i = 0; i < n_opt_val; i++) {
-	name = var_opt_val[i]
-	otype = var_opt_val_type[i];
-	if (otype ~ "^const char \\**$")
-		print "  bp_pack_string (ob, bp, ptr->" name", true);";
-	else
-		print "  bp_pack_value (bp, ptr->" name", 64);";
+for (i = 0; i < n_opt_other; i++) {
+	print "  bp_pack_value (bp, ptr->x_" var_opt_other[i] ", HOST_BITS_PER_WIDE_INT);";
+}
+for (i = 0; i < n_opt_int; i++) {
+	print "  bp_pack_value (bp, static_cast<unsigned int>(ptr->x_" var_opt_int[i] "), HOST_BITS_PER_INT);";
+}
+for (i = 0; i < n_opt_enum; i++) {
+	print "  bp_pack_value (bp, static_cast<unsigned int>(ptr->x_" var_opt_enum[i] "), HOST_BITS_PER_INT);";
+}
+for (i = 0; i < n_opt_short; i++) {
+	print "  bp_pack_value (bp, static_cast<unsigned short>(ptr->x_" var_opt_short[i] "), HOST_BITS_PER_SHORT);";
+}
+for (i = 0; i < n_opt_char; i++) {
+	print "  bp_pack_value (bp, static_cast<unsigned char>(ptr->x_" var_opt_char[i] "), HOST_BITS_PER_CHAR);";
+}
+for (i = 0; i < n_opt_string; i++) {
+	print "  bp_pack_string (ob, bp, ptr->x_" var_opt_string[i] ", true);";
 }
 print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
 print "    bp_pack_value (bp, ptr->explicit_mask[i], 64);";
@@ -1271,17 +1281,26 @@ print "cl_optimization_stream_in (struct
 print "                           struct bitpack_d *bp ATTRIBUTE_UNUSED,";
 print "                           struct cl_optimization *ptr ATTRIBUTE_UNUSED)";
 print "{";
-for (i = 0; i < n_opt_val; i++) {
-	name = var_opt_val[i]
-	otype = var_opt_val_type[i];
-	if (otype ~ "^const char \\**$")
-	{
-	      print "  ptr->" name" = bp_unpack_string (data_in, bp);";
-	      print "  if (ptr->" name")";
-	      print "    ptr->" name" = xstrdup (ptr->" name");";
-	}
-	else
-	      print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_value (bp, 64);";
+for (i = 0; i < n_opt_other; i++) {
+	print "  ptr->x_" var_opt_other[i] " = bp_unpack_value (bp, HOST_BITS_PER_WIDE_INT);";
+}
+for (i = 0; i < n_opt_int; i++) {
+	print "  ptr->x_" var_opt_int[i] " = bp_unpack_value (bp, HOST_BITS_PER_INT);";
+}
+for (i = 0; i < n_opt_enum; i++) {
+	print "  ptr->x_" var_opt_enum[i] " = static_cast<" var_opt_enum_type[i] ">(bp_unpack_value (bp, HOST_BITS_PER_INT));";
+}
+for (i = 0; i < n_opt_short; i++) {
+	print "  ptr->x_" var_opt_short[i] " = bp_unpack_value (bp, HOST_BITS_PER_SHORT);";
+}
+for (i = 0; i < n_opt_char; i++) {
+	print "  ptr->x_" var_opt_char[i] " = bp_unpack_value (bp, HOST_BITS_PER_CHAR);";
+}
+for (i = 0; i < n_opt_string; i++) {
+	name = var_opt_string[i];
+	print "  ptr->x_" name" = bp_unpack_string (data_in, bp);";
+	print "  if (ptr->x_" name")";
+	print "    ptr->x_" name" = xstrdup (ptr->x_" name");";
 }
 print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
 print "    ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";

	Jakub

Re: [PATCH] options, lto: Optimize streaming of optimization nodes

[Richard Biener]

On Sun, 13 Sep 2020, Jakub Jelinek wrote:

> Hi!
> 
> When working on the previous patch, I've noticed that all cl_optimization
> fields appart from strings are streamed with bp_pack_value (..., 64); so we
> waste quite a lot of space, given that many of the options are just booleans
> or char options and there are 450-ish of them.
> 
> Fixed by streaming the number of bits the corresponding fields have.
> While for char fields we have also range information, except for 3
> it is either -128, 127 or 0, 255, so it didn't seem worth it to bother
> with using range-ish packing.
> 
> Bootstrapped/regtested on x86_64-linux, i686-linux, armv7hl-linux-gnueabi,
> aarch64-linux, powerpc64le-linux and lto bootstrapped on x86_64-linux, ok
> for trunk?

Hmm, in principle the LTO bytecode format should be not dependent
on the host, while it probably doesn't work right now to move
32bit host to 64bit host targeting the same target bytecode files
the following makes explicit use of HOST_* and that might have been
the reason we're using 64bit encodings for everything.  Note
using 64bits isn't too bad in practice since we uleb encode the
bitpack words and outputing 64bits basically ensures we're outputting
a stream of uleb encoded uint64_t.

Richard.

> 2020-09-13  Jakub Jelinek  <jakub@redhat.com>
> 
> 	* optc-save-gen.awk: In cl_optimization_stream_out and
> 	cl_optimization_stream_in, stream int, enum, short and char
> 	variables with corresponding HOST_BITS_PER_* rather than
> 	hardcoded 64.
> 
> --- gcc/optc-save-gen.awk.jj	2020-09-11 17:38:31.524230167 +0200
> +++ gcc/optc-save-gen.awk	2020-09-11 22:12:59.948580827 +0200
> @@ -1252,13 +1252,23 @@ print "cl_optimization_stream_out (struc
>  print "                            struct bitpack_d *bp,";
>  print "                            struct cl_optimization *ptr)";
>  print "{";
> -for (i = 0; i < n_opt_val; i++) {
> -	name = var_opt_val[i]
> -	otype = var_opt_val_type[i];
> -	if (otype ~ "^const char \\**$")
> -		print "  bp_pack_string (ob, bp, ptr->" name", true);";
> -	else
> -		print "  bp_pack_value (bp, ptr->" name", 64);";
> +for (i = 0; i < n_opt_other; i++) {
> +	print "  bp_pack_value (bp, ptr->x_" var_opt_other[i] ", HOST_BITS_PER_WIDE_INT);";
> +}
> +for (i = 0; i < n_opt_int; i++) {
> +	print "  bp_pack_value (bp, static_cast<unsigned int>(ptr->x_" var_opt_int[i] "), HOST_BITS_PER_INT);";
> +}
> +for (i = 0; i < n_opt_enum; i++) {
> +	print "  bp_pack_value (bp, static_cast<unsigned int>(ptr->x_" var_opt_enum[i] "), HOST_BITS_PER_INT);";
> +}
> +for (i = 0; i < n_opt_short; i++) {
> +	print "  bp_pack_value (bp, static_cast<unsigned short>(ptr->x_" var_opt_short[i] "), HOST_BITS_PER_SHORT);";
> +}
> +for (i = 0; i < n_opt_char; i++) {
> +	print "  bp_pack_value (bp, static_cast<unsigned char>(ptr->x_" var_opt_char[i] "), HOST_BITS_PER_CHAR);";
> +}
> +for (i = 0; i < n_opt_string; i++) {
> +	print "  bp_pack_string (ob, bp, ptr->x_" var_opt_string[i] ", true);";
>  }
>  print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
>  print "    bp_pack_value (bp, ptr->explicit_mask[i], 64);";
> @@ -1271,17 +1281,26 @@ print "cl_optimization_stream_in (struct
>  print "                           struct bitpack_d *bp ATTRIBUTE_UNUSED,";
>  print "                           struct cl_optimization *ptr ATTRIBUTE_UNUSED)";
>  print "{";
> -for (i = 0; i < n_opt_val; i++) {
> -	name = var_opt_val[i]
> -	otype = var_opt_val_type[i];
> -	if (otype ~ "^const char \\**$")
> -	{
> -	      print "  ptr->" name" = bp_unpack_string (data_in, bp);";
> -	      print "  if (ptr->" name")";
> -	      print "    ptr->" name" = xstrdup (ptr->" name");";
> -	}
> -	else
> -	      print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_value (bp, 64);";
> +for (i = 0; i < n_opt_other; i++) {
> +	print "  ptr->x_" var_opt_other[i] " = bp_unpack_value (bp, HOST_BITS_PER_WIDE_INT);";
> +}
> +for (i = 0; i < n_opt_int; i++) {
> +	print "  ptr->x_" var_opt_int[i] " = bp_unpack_value (bp, HOST_BITS_PER_INT);";
> +}
> +for (i = 0; i < n_opt_enum; i++) {
> +	print "  ptr->x_" var_opt_enum[i] " = static_cast<" var_opt_enum_type[i] ">(bp_unpack_value (bp, HOST_BITS_PER_INT));";
> +}
> +for (i = 0; i < n_opt_short; i++) {
> +	print "  ptr->x_" var_opt_short[i] " = bp_unpack_value (bp, HOST_BITS_PER_SHORT);";
> +}
> +for (i = 0; i < n_opt_char; i++) {
> +	print "  ptr->x_" var_opt_char[i] " = bp_unpack_value (bp, HOST_BITS_PER_CHAR);";
> +}
> +for (i = 0; i < n_opt_string; i++) {
> +	name = var_opt_string[i];
> +	print "  ptr->x_" name" = bp_unpack_string (data_in, bp);";
> +	print "  if (ptr->x_" name")";
> +	print "    ptr->x_" name" = xstrdup (ptr->x_" name");";
>  }
>  print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
>  print "    ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)

Re: [PATCH] options, lto: Optimize streaming of optimization nodes

[Jakub Jelinek]

On Mon, Sep 14, 2020 at 08:39:22AM +0200, Richard Biener wrote:
> > When working on the previous patch, I've noticed that all cl_optimization
> > fields appart from strings are streamed with bp_pack_value (..., 64); so we
> > waste quite a lot of space, given that many of the options are just booleans
> > or char options and there are 450-ish of them.
> > 
> > Fixed by streaming the number of bits the corresponding fields have.
> > While for char fields we have also range information, except for 3
> > it is either -128, 127 or 0, 255, so it didn't seem worth it to bother
> > with using range-ish packing.
> > 
> > Bootstrapped/regtested on x86_64-linux, i686-linux, armv7hl-linux-gnueabi,
> > aarch64-linux, powerpc64le-linux and lto bootstrapped on x86_64-linux, ok
> > for trunk?
> 
> Hmm, in principle the LTO bytecode format should be not dependent
> on the host, while it probably doesn't work right now to move
> 32bit host to 64bit host targeting the same target bytecode files
> the following makes explicit use of HOST_* and that might have been
> the reason we're using 64bit encodings for everything.  Note
> using 64bits isn't too bad in practice since we uleb encode the
> bitpack words and outputing 64bits basically ensures we're outputting
> a stream of uleb encoded uint64_t.

So would using hardcoded 8, 16, 32 and 64 be better?
I mean, we certainly assume the -128, 127 or 0, 255 ranges e.g. for chars.
There are ~ 4 strings, 226 chars, 222 ints/enums in my options-save.c
bp_pack_* calls and 39 64-bit (which includes the target stuff) on
x86_64-linux.

Another option is using the variable length
bp_pack_var_len_unsigned/bp_pack_var_len_int
for everything, I guess most of the char options are 0/1/2, most of the
params are smallish too (though there are some 100s, 1000s and 10000s and
even higher, but most of them are small).
Either the awk script would need to figure out which are guaranteed to be
unsigned and use *_unsigned for them and use *_int for rest, or we'd need to
use *_int everywhere.

	Jakub

Re: [PATCH] options, lto: Optimize streaming of optimization nodes

[Richard Biener]

On Mon, 14 Sep 2020, Jakub Jelinek wrote:

> On Mon, Sep 14, 2020 at 08:39:22AM +0200, Richard Biener wrote:
> > > When working on the previous patch, I've noticed that all cl_optimization
> > > fields appart from strings are streamed with bp_pack_value (..., 64); so we
> > > waste quite a lot of space, given that many of the options are just booleans
> > > or char options and there are 450-ish of them.
> > > 
> > > Fixed by streaming the number of bits the corresponding fields have.
> > > While for char fields we have also range information, except for 3
> > > it is either -128, 127 or 0, 255, so it didn't seem worth it to bother
> > > with using range-ish packing.
> > > 
> > > Bootstrapped/regtested on x86_64-linux, i686-linux, armv7hl-linux-gnueabi,
> > > aarch64-linux, powerpc64le-linux and lto bootstrapped on x86_64-linux, ok
> > > for trunk?
> > 
> > Hmm, in principle the LTO bytecode format should be not dependent
> > on the host, while it probably doesn't work right now to move
> > 32bit host to 64bit host targeting the same target bytecode files
> > the following makes explicit use of HOST_* and that might have been
> > the reason we're using 64bit encodings for everything.  Note
> > using 64bits isn't too bad in practice since we uleb encode the
> > bitpack words and outputing 64bits basically ensures we're outputting
> > a stream of uleb encoded uint64_t.
> 
> So would using hardcoded 8, 16, 32 and 64 be better?
> I mean, we certainly assume the -128, 127 or 0, 255 ranges e.g. for chars.
> There are ~ 4 strings, 226 chars, 222 ints/enums in my options-save.c
> bp_pack_* calls and 39 64-bit (which includes the target stuff) on
> x86_64-linux.
>
> Another option is using the variable length
> bp_pack_var_len_unsigned/bp_pack_var_len_int
> for everything, I guess most of the char options are 0/1/2, most of the
> params are smallish too (though there are some 100s, 1000s and 10000s and
> even higher, but most of them are small).
> Either the awk script would need to figure out which are guaranteed to be
> unsigned and use *_unsigned for them and use *_int for rest, or we'd need to
> use *_int everywhere.

But does it make any noticable difference in the end?  Using
bp_pack_var_len_unsigned just causes us to [u]leb encode half-bytes
rather than full bytes.  Using hardcoded 8/16/32/64 makes it still
dependent on what 'int' is at maximum on the host.

That is, I'd indeed prefer bp_pack_var_len_unsigned over hard-coding
8, 16, etc., but can you share a size comparison of the bitpack?
I guess with bp_pack_var_len_unsigned it might shrink in half
compared to the current code and streaming standard -O2?

Richard.
 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)

Re: [PATCH] options, lto: Optimize streaming of optimization nodes

[Jakub Jelinek]

On Mon, Sep 14, 2020 at 09:31:52AM +0200, Richard Biener wrote:
> But does it make any noticable difference in the end?  Using

Yes.

> bp_pack_var_len_unsigned just causes us to [u]leb encode half-bytes
> rather than full bytes.  Using hardcoded 8/16/32/64 makes it still
> dependent on what 'int' is at maximum on the host.
> 
> That is, I'd indeed prefer bp_pack_var_len_unsigned over hard-coding
> 8, 16, etc., but can you share a size comparison of the bitpack?
> I guess with bp_pack_var_len_unsigned it might shrink in half
> compared to the current code and streaming standard -O2?

So, I've tried
--- gcc/tree-streamer-out.c.jj	2020-07-28 15:39:10.079755251 +0200
+++ gcc/tree-streamer-out.c	2020-09-14 10:31:29.106957258 +0200
@@ -489,7 +489,11 @@ streamer_write_tree_bitfields (struct ou
     pack_ts_translation_unit_decl_value_fields (ob, &bp, expr);
 
   if (CODE_CONTAINS_STRUCT (code, TS_OPTIMIZATION))
+{
+long ts = ob->main_stream->total_size;
     cl_optimization_stream_out (ob, &bp, TREE_OPTIMIZATION (expr));
+fprintf (stderr, "total_size %ld\n", (long) (ob->main_stream->total_size - ts));
+}
 
   if (CODE_CONTAINS_STRUCT (code, TS_CONSTRUCTOR))
     bp_pack_var_len_unsigned (&bp, CONSTRUCTOR_NELTS (expr));
hack without and with the following patch on a simple small testcase with
-O2 -flto.
Got 574 bytes without the opc-save-gen.awk change and 454 bytes with it,
that is ~ 21% saving on the TREE_OPTIMIZATION streaming.

2020-09-14  Jakub Jelinek  <jakub@redhat.com>

	* optc-save-gen.awk: In cl_optimization_stream_out use
	bp_pack_var_len_{int,unsigned} instead of bp_pack_value.  In
	cl_optimization_stream_in use bp_unpack_var_len_{int,unsigned}
	instead of bp_unpack_value.  Formatting fix.

--- gcc/optc-save-gen.awk.jj	2020-09-14 09:04:35.879854156 +0200
+++ gcc/optc-save-gen.awk	2020-09-14 10:38:47.722424942 +0200
@@ -1257,8 +1257,10 @@ for (i = 0; i < n_opt_val; i++) {
 	otype = var_opt_val_type[i];
 	if (otype ~ "^const char \\**$")
 		print "  bp_pack_string (ob, bp, ptr->" name", true);";
+	else if (otype ~ "^unsigned")
+		print "  bp_pack_var_len_unsigned (bp, ptr->" name");";
 	else
-		print "  bp_pack_value (bp, ptr->" name", 64);";
+		print "  bp_pack_var_len_int (bp, ptr->" name");";
 }
 print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
 print "    bp_pack_value (bp, ptr->explicit_mask[i], 64);";
@@ -1274,14 +1276,15 @@ print "{";
 for (i = 0; i < n_opt_val; i++) {
 	name = var_opt_val[i]
 	otype = var_opt_val_type[i];
-	if (otype ~ "^const char \\**$")
-	{
-	      print "  ptr->" name" = bp_unpack_string (data_in, bp);";
-	      print "  if (ptr->" name")";
-	      print "    ptr->" name" = xstrdup (ptr->" name");";
+	if (otype ~ "^const char \\**$") {
+		print "  ptr->" name" = bp_unpack_string (data_in, bp);";
+		print "  if (ptr->" name")";
+		print "    ptr->" name" = xstrdup (ptr->" name");";
 	}
+	else if (otype ~ "^unsigned")
+		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_unsigned (bp);";
 	else
-	      print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_value (bp, 64);";
+		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_int (bp);";
 }
 print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
 print "    ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";


	Jakub

Re: [PATCH] options, lto: Optimize streaming of optimization nodes

[Jan Hubicka]

> On Mon, Sep 14, 2020 at 09:31:52AM +0200, Richard Biener wrote:
> > But does it make any noticable difference in the end?  Using
> 
> Yes.
> 
> > bp_pack_var_len_unsigned just causes us to [u]leb encode half-bytes
> > rather than full bytes.  Using hardcoded 8/16/32/64 makes it still
> > dependent on what 'int' is at maximum on the host.
> > 
> > That is, I'd indeed prefer bp_pack_var_len_unsigned over hard-coding
> > 8, 16, etc., but can you share a size comparison of the bitpack?
> > I guess with bp_pack_var_len_unsigned it might shrink in half
> > compared to the current code and streaming standard -O2?
> 
> So, I've tried
> --- gcc/tree-streamer-out.c.jj	2020-07-28 15:39:10.079755251 +0200
> +++ gcc/tree-streamer-out.c	2020-09-14 10:31:29.106957258 +0200
> @@ -489,7 +489,11 @@ streamer_write_tree_bitfields (struct ou
>      pack_ts_translation_unit_decl_value_fields (ob, &bp, expr);
>  
>    if (CODE_CONTAINS_STRUCT (code, TS_OPTIMIZATION))
> +{
> +long ts = ob->main_stream->total_size;
>      cl_optimization_stream_out (ob, &bp, TREE_OPTIMIZATION (expr));
> +fprintf (stderr, "total_size %ld\n", (long) (ob->main_stream->total_size - ts));
> +}

You should be able to read the sizes from streaming dump file as well.
>  
>    if (CODE_CONTAINS_STRUCT (code, TS_CONSTRUCTOR))
>      bp_pack_var_len_unsigned (&bp, CONSTRUCTOR_NELTS (expr));
> hack without and with the following patch on a simple small testcase with
> -O2 -flto.
> Got 574 bytes without the opc-save-gen.awk change and 454 bytes with it,
> that is ~ 21% saving on the TREE_OPTIMIZATION streaming.
> 
> 2020-09-14  Jakub Jelinek  <jakub@redhat.com>
> 
> 	* optc-save-gen.awk: In cl_optimization_stream_out use
> 	bp_pack_var_len_{int,unsigned} instead of bp_pack_value.  In
> 	cl_optimization_stream_in use bp_unpack_var_len_{int,unsigned}
> 	instead of bp_unpack_value.  Formatting fix.
> 
> --- gcc/optc-save-gen.awk.jj	2020-09-14 09:04:35.879854156 +0200
> +++ gcc/optc-save-gen.awk	2020-09-14 10:38:47.722424942 +0200
> @@ -1257,8 +1257,10 @@ for (i = 0; i < n_opt_val; i++) {
>  	otype = var_opt_val_type[i];
>  	if (otype ~ "^const char \\**$")
>  		print "  bp_pack_string (ob, bp, ptr->" name", true);";
> +	else if (otype ~ "^unsigned")
> +		print "  bp_pack_var_len_unsigned (bp, ptr->" name");";
>  	else
> -		print "  bp_pack_value (bp, ptr->" name", 64);";
> +		print "  bp_pack_var_len_int (bp, ptr->" name");";
>  }
>  print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
>  print "    bp_pack_value (bp, ptr->explicit_mask[i], 64);";
> @@ -1274,14 +1276,15 @@ print "{";
>  for (i = 0; i < n_opt_val; i++) {
>  	name = var_opt_val[i]
>  	otype = var_opt_val_type[i];
> -	if (otype ~ "^const char \\**$")
> -	{
> -	      print "  ptr->" name" = bp_unpack_string (data_in, bp);";
> -	      print "  if (ptr->" name")";
> -	      print "    ptr->" name" = xstrdup (ptr->" name");";
> +	if (otype ~ "^const char \\**$") {
> +		print "  ptr->" name" = bp_unpack_string (data_in, bp);";
> +		print "  if (ptr->" name")";
> +		print "    ptr->" name" = xstrdup (ptr->" name");";
>  	}
> +	else if (otype ~ "^unsigned")
> +		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_unsigned (bp);";
>  	else
> -	      print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_value (bp, 64);";
> +		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_int (bp);";

Not making difference between signed/unsigned was my implementation
lazyness at the time code was added. So this looks like nice cleanup.

Especially for the new param machinery, most of streamed values are
probably going to be the default values.  Perhaps somehow we could
stream them more effectively.

Overall we sould not get much more than 1 optimize/target node per unit
so the size should show up only when you stream a lot of very small .o
files.

Honza
>  }
>  print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
>  print "    ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";
> 
> 
> 	Jakub
> 

Re: [PATCH] options, lto: Optimize streaming of optimization nodes

[Jakub Jelinek]

On Mon, Sep 14, 2020 at 11:02:26AM +0200, Jan Hubicka wrote:
> Especially for the new param machinery, most of streamed values are
> probably going to be the default values.  Perhaps somehow we could
> stream them more effectively.

Ah, that seems like a good idea, that brings further savings, the size
goes down from 574 bytes to 273 bytes, i.e. less than half.
Here is an updated version that does that.  Not trying to handle
enums because the code doesn't know if (enum ...) 10 is even valid,
similarly non-parameters because those really generally don't have large
initializers, and params without Init (those are 0 initialized and thus
don't need to be handled).

2020-09-14  Jakub Jelinek  <jakub@redhat.com>

	* optc-save-gen.awk: Initialize var_opt_init.  In
	cl_optimization_stream_out use bp_pack_var_len_{int,unsigned} instead
	of bp_pack_value and for params with default values larger than 10, xor
	the default value with the actual parameter value.  In
	cl_optimization_stream_in use bp_unpack_var_len_{int,unsigned}
	instead of bp_unpack_value and repeat the above xor.  Formatting fix.

--- gcc/optc-save-gen.awk.jj	2020-09-14 10:51:54.493740942 +0200
+++ gcc/optc-save-gen.awk	2020-09-14 11:39:39.441602594 +0200
@@ -1186,6 +1186,7 @@ for (i = 0; i < n_opts; i++) {
 		var_opt_val_type[n_opt_val] = otype;
 		var_opt_val[n_opt_val] = "x_" name;
 		var_opt_hash[n_opt_val] = flag_set_p("Optimization", flags[i]);
+		var_opt_init[n_opt_val] = opt_args("Init", flags[i]);
 		n_opt_val++;
 	}
 }
@@ -1257,8 +1258,21 @@ for (i = 0; i < n_opt_val; i++) {
 	otype = var_opt_val_type[i];
 	if (otype ~ "^const char \\**$")
 		print "  bp_pack_string (ob, bp, ptr->" name", true);";
-	else
-		print "  bp_pack_value (bp, ptr->" name", 64);";
+	else {
+		if (otype ~ "^unsigned") {
+			sgn = "unsigned";
+		} else {
+			sgn = "int";
+		}
+		if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
+			print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
+			print "    bp_pack_var_len_" sgn " (bp, ptr->" name" ^ " var_opt_init[i] ");";
+			print "  else";
+			print "    bp_pack_var_len_" sgn " (bp, ptr->" name");";
+		} else {
+			print "  bp_pack_var_len_" sgn " (bp, ptr->" name");";
+		}
+	}
 }
 print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
 print "    bp_pack_value (bp, ptr->explicit_mask[i], 64);";
@@ -1274,14 +1288,23 @@ print "{";
 for (i = 0; i < n_opt_val; i++) {
 	name = var_opt_val[i]
 	otype = var_opt_val_type[i];
-	if (otype ~ "^const char \\**$")
-	{
-	      print "  ptr->" name" = bp_unpack_string (data_in, bp);";
-	      print "  if (ptr->" name")";
-	      print "    ptr->" name" = xstrdup (ptr->" name");";
+	if (otype ~ "^const char \\**$") {
+		print "  ptr->" name" = bp_unpack_string (data_in, bp);";
+		print "  if (ptr->" name")";
+		print "    ptr->" name" = xstrdup (ptr->" name");";
+	}
+	else {
+		if (otype ~ "^unsigned") {
+			sgn = "unsigned";
+		} else {
+			sgn = "int";
+		}
+		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_" sgn " (bp);";
+		if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
+			print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
+			print "    ptr->" name" ^= " var_opt_init[i] ";";
+		}
 	}
-	else
-	      print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_value (bp, 64);";
 }
 print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
 print "    ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";


	Jakub

Patch ping (Re: [PATCH] options, lto: Optimize streaming of optimization nodes)

[Jakub Jelinek]

On Mon, Sep 14, 2020 at 11:47:56AM +0200, Jakub Jelinek via Gcc-patches wrote:
> On Mon, Sep 14, 2020 at 11:02:26AM +0200, Jan Hubicka wrote:
> > Especially for the new param machinery, most of streamed values are
> > probably going to be the default values.  Perhaps somehow we could
> > stream them more effectively.
> 
> Ah, that seems like a good idea, that brings further savings, the size
> goes down from 574 bytes to 273 bytes, i.e. less than half.
> Here is an updated version that does that.  Not trying to handle
> enums because the code doesn't know if (enum ...) 10 is even valid,
> similarly non-parameters because those really generally don't have large
> initializers, and params without Init (those are 0 initialized and thus
> don't need to be handled).

Here is an updated version of that on top of what has been committed.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2020-09-16  Jakub Jelinek  <jakub@redhat.com>

	* optc-save-gen.awk: Initialize var_opt_init.  In
	cl_optimization_stream_out for params with default values larger than
	10, xor the default value with the actual parameter value.  In
	cl_optimization_stream_in repeat the above xor.

--- gcc/optc-save-gen.awk.jj	2020-09-14 10:51:54.493740942 +0200
+++ gcc/optc-save-gen.awk	2020-09-14 11:39:39.441602594 +0200
@@ -1186,6 +1186,7 @@ for (i = 0; i < n_opts; i++) {
 		var_opt_val_type[n_opt_val] = otype;
 		var_opt_val[n_opt_val] = "x_" name;
 		var_opt_hash[n_opt_val] = flag_set_p("Optimization", flags[i]);
+		var_opt_init[n_opt_val] = opt_args("Init", flags[i]);
 		n_opt_val++;
 	}
 }
@@ -1257,10 +1258,21 @@ for (i = 0; i < n_opt_val; i++) {
 	otype = var_opt_val_type[i];
 	if (otype ~ "^const char \\**$")
 		print "  bp_pack_string (ob, bp, ptr->" name", true);";
-	else if (otype ~ "^unsigned")
-		print "  bp_pack_var_len_unsigned (bp, ptr->" name");";
-	else
-		print "  bp_pack_var_len_int (bp, ptr->" name");";
+	else {
+		if (otype ~ "^unsigned") {
+			sgn = "unsigned";
+		} else {
+			sgn = "int";
+		}
+		if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
+			print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
+			print "    bp_pack_var_len_" sgn " (bp, ptr->" name" ^ " var_opt_init[i] ");";
+			print "  else";
+			print "    bp_pack_var_len_" sgn " (bp, ptr->" name");";
+		} else {
+			print "  bp_pack_var_len_" sgn " (bp, ptr->" name");";
+		}
+	}
 }
 print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
 print "    bp_pack_value (bp, ptr->explicit_mask[i], 64);";
@@ -1281,10 +1293,18 @@ for (i = 0; i < n_opt_val; i++) {
 		print "  if (ptr->" name")";
 		print "    ptr->" name" = xstrdup (ptr->" name");";
 	}
-	else if (otype ~ "^unsigned")
-		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_unsigned (bp);";
-	else
-		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_int (bp);";
+	else {
+		if (otype ~ "^unsigned") {
+			sgn = "unsigned";
+		} else {
+			sgn = "int";
+		}
+		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_" sgn " (bp);";
+		if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
+			print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
+			print "    ptr->" name" ^= " var_opt_init[i] ";";
+		}
+	}
 }
 print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
 print "    ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";


	Jakub

[PATCH] options, lto: Optimize streaming of optimization nodes

[Jakub Jelinek]

Hi!

Reposting with self-contained description per Joseph's request:

Honza mentioned that especially for the new param machinery, most of
streamed values are probably going to be the default values.  Perhaps
somehow we could stream them more effectively.

This patch implements it and brings further savings, the size
goes down from 574 bytes to 273 bytes, i.e. less than half.
Not trying to handle enums because the code doesn't know if (enum ...) 10
is even valid, similarly non-parameters because those really generally
don't have large initializers, and params without Init (those are 0
initialized and thus don't need to be handled).

Bootstrapped/regtested again on x86_64-linux and i686-linux, ok for trunk?

2020-11-18  Jakub Jelinek  <jakub@redhat.com>

	* optc-save-gen.awk: Initialize var_opt_init.  In
	cl_optimization_stream_out for params with default values larger than
	10, xor the default value with the actual parameter value.  In
	cl_optimization_stream_in repeat the above xor.

--- gcc/optc-save-gen.awk.jj	2020-09-14 10:51:54.493740942 +0200
+++ gcc/optc-save-gen.awk	2020-09-14 11:39:39.441602594 +0200
@@ -1186,6 +1186,7 @@ for (i = 0; i < n_opts; i++) {
 		var_opt_val_type[n_opt_val] = otype;
 		var_opt_val[n_opt_val] = "x_" name;
 		var_opt_hash[n_opt_val] = flag_set_p("Optimization", flags[i]);
+		var_opt_init[n_opt_val] = opt_args("Init", flags[i]);
 		n_opt_val++;
 	}
 }
@@ -1257,10 +1258,21 @@ for (i = 0; i < n_opt_val; i++) {
 	otype = var_opt_val_type[i];
 	if (otype ~ "^const char \\**$")
 		print "  bp_pack_string (ob, bp, ptr->" name", true);";
-	else if (otype ~ "^unsigned")
-		print "  bp_pack_var_len_unsigned (bp, ptr->" name");";
-	else
-		print "  bp_pack_var_len_int (bp, ptr->" name");";
+	else {
+		if (otype ~ "^unsigned") {
+			sgn = "unsigned";
+		} else {
+			sgn = "int";
+		}
+		if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
+			print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
+			print "    bp_pack_var_len_" sgn " (bp, ptr->" name" ^ " var_opt_init[i] ");";
+			print "  else";
+			print "    bp_pack_var_len_" sgn " (bp, ptr->" name");";
+		} else {
+			print "  bp_pack_var_len_" sgn " (bp, ptr->" name");";
+		}
+	}
 }
 print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
 print "    bp_pack_value (bp, ptr->explicit_mask[i], 64);";
@@ -1281,10 +1293,18 @@ for (i = 0; i < n_opt_val; i++) {
 		print "  if (ptr->" name")";
 		print "    ptr->" name" = xstrdup (ptr->" name");";
 	}
-	else if (otype ~ "^unsigned")
-		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_unsigned (bp);";
-	else
-		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_int (bp);";
+	else {
+		if (otype ~ "^unsigned") {
+			sgn = "unsigned";
+		} else {
+			sgn = "int";
+		}
+		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_" sgn " (bp);";
+		if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
+			print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
+			print "    ptr->" name" ^= " var_opt_init[i] ";";
+		}
+	}
 }
 print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
 print "    ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";


	Jakub

Re: [PATCH] options, lto: Optimize streaming of optimization nodes

[Joseph Myers]

On Wed, 18 Nov 2020, Jakub Jelinek via Gcc-patches wrote:

> Hi!
> 
> Reposting with self-contained description per Joseph's request:
> 
> Honza mentioned that especially for the new param machinery, most of
> streamed values are probably going to be the default values.  Perhaps
> somehow we could stream them more effectively.
> 
> This patch implements it and brings further savings, the size
> goes down from 574 bytes to 273 bytes, i.e. less than half.
> Not trying to handle enums because the code doesn't know if (enum ...) 10
> is even valid, similarly non-parameters because those really generally
> don't have large initializers, and params without Init (those are 0
> initialized and thus don't need to be handled).
> 
> Bootstrapped/regtested again on x86_64-linux and i686-linux, ok for trunk?
> 
> 2020-11-18  Jakub Jelinek  <jakub@redhat.com>
> 
> 	* optc-save-gen.awk: Initialize var_opt_init.  In
> 	cl_optimization_stream_out for params with default values larger than
> 	10, xor the default value with the actual parameter value.  In
> 	cl_optimization_stream_in repeat the above xor.

OK.

-- 
Joseph S. Myers
joseph@codesourcery.com

options: Clarify 'Init' option property usage for streaming optimization (was: [PATCH] options, lto: Optimize streaming of optimization nodes)

[Thomas Schwinge]

[-- Attachment #1: Type: text/plain, Size: 4976 bytes --]

Hi!

On 2020-11-18T10:36:35+0100, Jakub Jelinek via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> Honza mentioned that especially for the new param machinery, most of
> streamed values are probably going to be the default values.  Perhaps
> somehow we could stream them more effectively.
>
> This patch implements it and brings further savings, the size
> goes down from 574 bytes to 273 bytes, i.e. less than half.

Neat idea about the XOR-encoding!

> Not trying to handle enums because the code doesn't know if (enum ...) 10
> is even valid, similarly non-parameters because those really generally
> don't have large initializers, and params without Init (those are 0
> initialized and thus don't need to be handled).

Given this only looks at 'Init', I understand this may actually
mis-optimize in the case that there is an 'Init' present, but that value
is then "by default" overridden via 'LANG_HOOKS_INIT_OPTIONS_STRUCT', or
'TARGET_OPTION_OVERRIDE', for example.  (I'm however not claiming that's
an actual problem to be worried about -- just for my understanding.)

Either way:

>       * optc-save-gen.awk: Initialize var_opt_init.  In
>       cl_optimization_stream_out for params with default values larger than
>       10, xor the default value with the actual parameter value.  In
>       cl_optimization_stream_in repeat the above xor.

> --- gcc/optc-save-gen.awk.jj  2020-09-14 10:51:54.493740942 +0200
> +++ gcc/optc-save-gen.awk     2020-09-14 11:39:39.441602594 +0200
> @@ -1186,6 +1186,7 @@ for (i = 0; i < n_opts; i++) {
>               var_opt_val_type[n_opt_val] = otype;
>               var_opt_val[n_opt_val] = "x_" name;
>               var_opt_hash[n_opt_val] = flag_set_p("Optimization", flags[i]);
> +             var_opt_init[n_opt_val] = opt_args("Init", flags[i]);
>               n_opt_val++;
>       }
>  }

Reading through the options handling, I was confused why 'Init' needs to
be handled in 'gcc/optc-save-gen.awk'.  To help the next person -- like,
me in a few weeks ;-) -- wondering about this, OK to push the attached
"options: Clarify 'Init' option property usage for streaming
optimization"?


Grüße
 Thomas


> @@ -1257,10 +1258,21 @@ for (i = 0; i < n_opt_val; i++) {
>       otype = var_opt_val_type[i];
>       if (otype ~ "^const char \\**$")
>               print "  bp_pack_string (ob, bp, ptr->" name", true);";
> -     else if (otype ~ "^unsigned")
> -             print "  bp_pack_var_len_unsigned (bp, ptr->" name");";
> -     else
> -             print "  bp_pack_var_len_int (bp, ptr->" name");";
> +     else {
> +             if (otype ~ "^unsigned") {
> +                     sgn = "unsigned";
> +             } else {
> +                     sgn = "int";
> +             }
> +             if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
> +                     print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
> +                     print "    bp_pack_var_len_" sgn " (bp, ptr->" name" ^ " var_opt_init[i] ");";
> +                     print "  else";
> +                     print "    bp_pack_var_len_" sgn " (bp, ptr->" name");";
> +             } else {
> +                     print "  bp_pack_var_len_" sgn " (bp, ptr->" name");";
> +             }
> +     }
>  }
>  print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
>  print "    bp_pack_value (bp, ptr->explicit_mask[i], 64);";
> @@ -1281,10 +1293,18 @@ for (i = 0; i < n_opt_val; i++) {
>               print "  if (ptr->" name")";
>               print "    ptr->" name" = xstrdup (ptr->" name");";
>       }
> -     else if (otype ~ "^unsigned")
> -             print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_unsigned (bp);";
> -     else
> -             print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_int (bp);";
> +     else {
> +             if (otype ~ "^unsigned") {
> +                     sgn = "unsigned";
> +             } else {
> +                     sgn = "int";
> +             }
> +             print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_" sgn " (bp);";
> +             if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
> +                     print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
> +                     print "    ptr->" name" ^= " var_opt_init[i] ";";
> +             }
> +     }
>  }
>  print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
>  print "    ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";


-----------------
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[-- Attachment #2: 0001-options-Clarify-Init-option-property-usage-for-strea.patch --]
[-- Type: text/x-diff, Size: 2979 bytes --]

From c7968fa44b1073dfa7da3a11470a9e76b6faafaf Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Thu, 31 Mar 2022 12:06:29 +0200
Subject: [PATCH] options: Clarify 'Init' option property usage for streaming
 optimization

This clarifies commit 95db7e9afe57ca1c269d46baa2accced004e5c74
"options, lto: Optimize streaming of optimization nodes".

No functional change; no change in generated files.

	gcc/
	* optc-save-gen.awk: Clarify 'Init' option property usage for
	streaming optimization.
---
 gcc/optc-save-gen.awk | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/gcc/optc-save-gen.awk b/gcc/optc-save-gen.awk
index 9911bab6668..c60b300f693 100644
--- a/gcc/optc-save-gen.awk
+++ b/gcc/optc-save-gen.awk
@@ -1292,7 +1292,22 @@ for (i = 0; i < n_opts; i++) {
 		var_opt_val_type[n_opt_val] = otype;
 		var_opt_val[n_opt_val] = "x_" name;
 		var_opt_hash[n_opt_val] = flag_set_p("Optimization", flags[i]);
-		var_opt_init[n_opt_val] = opt_args("Init", flags[i]);
+
+		# If applicable, optimize streaming for the common case that
+		# the current value is unchanged from the 'Init' value:
+		# XOR-encode it so that we stream value zero.
+		# Not handling non-parameters as those really generally don't
+		# have large initializers.
+		# Not handling enums as we don't know if '(enum ...) 10' is
+		# even valid (see synthesized 'if' conditionals below).
+		if (flag_set_p("Param", flags[i]) \
+		    && !(otype ~ "^enum ")) {
+			# Those without 'Init' are zero-initialized and thus
+			# already encoded ideally.
+			init = opt_args("Init", flags[i])
+			var_opt_optimize_init[n_opt_val] = init;
+		}
+
 		n_opt_val++;
 	}
 }
@@ -1370,9 +1385,10 @@ for (i = 0; i < n_opt_val; i++) {
 		} else {
 			sgn = "int";
 		}
-		if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
-			print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
-			print "    bp_pack_var_len_" sgn " (bp, ptr->" name" ^ " var_opt_init[i] ");";
+		# If applicable, encode the streamed value.
+		if (var_opt_optimize_init[i]) {
+			print "  if (" var_opt_optimize_init[i] " > (" var_opt_val_type[i] ") 10)";
+			print "    bp_pack_var_len_" sgn " (bp, ptr->" name" ^ " var_opt_optimize_init[i] ");";
 			print "  else";
 			print "    bp_pack_var_len_" sgn " (bp, ptr->" name");";
 		} else {
@@ -1406,9 +1422,10 @@ for (i = 0; i < n_opt_val; i++) {
 			sgn = "int";
 		}
 		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_" sgn " (bp);";
-		if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
-			print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
-			print "    ptr->" name" ^= " var_opt_init[i] ";";
+		# If applicable, decode the streamed value.
+		if (var_opt_optimize_init[i]) {
+			print "  if (" var_opt_optimize_init[i] " > (" var_opt_val_type[i] ") 10)";
+			print "    ptr->" name" ^= " var_opt_optimize_init[i] ";";
 		}
 	}
 }
-- 
2.35.1

[PING] options: Clarify 'Init' option property usage for streaming optimization (was: [PATCH] options, lto: Optimize streaming of optimization nodes)

[Thomas Schwinge]

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Hi!

Ping.  For convenience, I've re-attached
"options: Clarify 'Init' option property usage for streaming optimization".
(I've re-verified: "No functional change; no change in generated files.")


Grüße
 Thomas


On 2022-03-31T15:22:59+0200, I wrote:
> Hi!
>
> On 2020-11-18T10:36:35+0100, Jakub Jelinek via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
>> Honza mentioned that especially for the new param machinery, most of
>> streamed values are probably going to be the default values.  Perhaps
>> somehow we could stream them more effectively.
>>
>> This patch implements it and brings further savings, the size
>> goes down from 574 bytes to 273 bytes, i.e. less than half.
>
> Neat idea about the XOR-encoding!
>
>> Not trying to handle enums because the code doesn't know if (enum ...) 10
>> is even valid, similarly non-parameters because those really generally
>> don't have large initializers, and params without Init (those are 0
>> initialized and thus don't need to be handled).
>
> Given this only looks at 'Init', I understand this may actually
> mis-optimize in the case that there is an 'Init' present, but that value
> is then "by default" overridden via 'LANG_HOOKS_INIT_OPTIONS_STRUCT', or
> 'TARGET_OPTION_OVERRIDE', for example.  (I'm however not claiming that's
> an actual problem to be worried about -- just for my understanding.)
>
> Either way:
>
>>      * optc-save-gen.awk: Initialize var_opt_init.  In
>>      cl_optimization_stream_out for params with default values larger than
>>      10, xor the default value with the actual parameter value.  In
>>      cl_optimization_stream_in repeat the above xor.
>
>> --- gcc/optc-save-gen.awk.jj 2020-09-14 10:51:54.493740942 +0200
>> +++ gcc/optc-save-gen.awk    2020-09-14 11:39:39.441602594 +0200
>> @@ -1186,6 +1186,7 @@ for (i = 0; i < n_opts; i++) {
>>              var_opt_val_type[n_opt_val] = otype;
>>              var_opt_val[n_opt_val] = "x_" name;
>>              var_opt_hash[n_opt_val] = flag_set_p("Optimization", flags[i]);
>> +            var_opt_init[n_opt_val] = opt_args("Init", flags[i]);
>>              n_opt_val++;
>>      }
>>  }
>
> Reading through the options handling, I was confused why 'Init' needs to
> be handled in 'gcc/optc-save-gen.awk'.  To help the next person -- like,
> me in a few weeks ;-) -- wondering about this, OK to push the attached
> "options: Clarify 'Init' option property usage for streaming
> optimization"?
>
>
> Grüße
>  Thomas
>
>
>> @@ -1257,10 +1258,21 @@ for (i = 0; i < n_opt_val; i++) {
>>      otype = var_opt_val_type[i];
>>      if (otype ~ "^const char \\**$")
>>              print "  bp_pack_string (ob, bp, ptr->" name", true);";
>> -    else if (otype ~ "^unsigned")
>> -            print "  bp_pack_var_len_unsigned (bp, ptr->" name");";
>> -    else
>> -            print "  bp_pack_var_len_int (bp, ptr->" name");";
>> +    else {
>> +            if (otype ~ "^unsigned") {
>> +                    sgn = "unsigned";
>> +            } else {
>> +                    sgn = "int";
>> +            }
>> +            if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
>> +                    print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
>> +                    print "    bp_pack_var_len_" sgn " (bp, ptr->" name" ^ " var_opt_init[i] ");";
>> +                    print "  else";
>> +                    print "    bp_pack_var_len_" sgn " (bp, ptr->" name");";
>> +            } else {
>> +                    print "  bp_pack_var_len_" sgn " (bp, ptr->" name");";
>> +            }
>> +    }
>>  }
>>  print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
>>  print "    bp_pack_value (bp, ptr->explicit_mask[i], 64);";
>> @@ -1281,10 +1293,18 @@ for (i = 0; i < n_opt_val; i++) {
>>              print "  if (ptr->" name")";
>>              print "    ptr->" name" = xstrdup (ptr->" name");";
>>      }
>> -    else if (otype ~ "^unsigned")
>> -            print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_unsigned (bp);";
>> -    else
>> -            print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_int (bp);";
>> +    else {
>> +            if (otype ~ "^unsigned") {
>> +                    sgn = "unsigned";
>> +            } else {
>> +                    sgn = "int";
>> +            }
>> +            print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_" sgn " (bp);";
>> +            if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
>> +                    print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
>> +                    print "    ptr->" name" ^= " var_opt_init[i] ";";
>> +            }
>> +    }
>>  }
>>  print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
>>  print "    ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";


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From c7968fa44b1073dfa7da3a11470a9e76b6faafaf Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Thu, 31 Mar 2022 12:06:29 +0200
Subject: [PATCH] options: Clarify 'Init' option property usage for streaming
 optimization

This clarifies commit 95db7e9afe57ca1c269d46baa2accced004e5c74
"options, lto: Optimize streaming of optimization nodes".

No functional change; no change in generated files.

	gcc/
	* optc-save-gen.awk: Clarify 'Init' option property usage for
	streaming optimization.
---
 gcc/optc-save-gen.awk | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/gcc/optc-save-gen.awk b/gcc/optc-save-gen.awk
index 9911bab6668..c60b300f693 100644
--- a/gcc/optc-save-gen.awk
+++ b/gcc/optc-save-gen.awk
@@ -1292,7 +1292,22 @@ for (i = 0; i < n_opts; i++) {
 		var_opt_val_type[n_opt_val] = otype;
 		var_opt_val[n_opt_val] = "x_" name;
 		var_opt_hash[n_opt_val] = flag_set_p("Optimization", flags[i]);
-		var_opt_init[n_opt_val] = opt_args("Init", flags[i]);
+
+		# If applicable, optimize streaming for the common case that
+		# the current value is unchanged from the 'Init' value:
+		# XOR-encode it so that we stream value zero.
+		# Not handling non-parameters as those really generally don't
+		# have large initializers.
+		# Not handling enums as we don't know if '(enum ...) 10' is
+		# even valid (see synthesized 'if' conditionals below).
+		if (flag_set_p("Param", flags[i]) \
+		    && !(otype ~ "^enum ")) {
+			# Those without 'Init' are zero-initialized and thus
+			# already encoded ideally.
+			init = opt_args("Init", flags[i])
+			var_opt_optimize_init[n_opt_val] = init;
+		}
+
 		n_opt_val++;
 	}
 }
@@ -1370,9 +1385,10 @@ for (i = 0; i < n_opt_val; i++) {
 		} else {
 			sgn = "int";
 		}
-		if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
-			print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
-			print "    bp_pack_var_len_" sgn " (bp, ptr->" name" ^ " var_opt_init[i] ");";
+		# If applicable, encode the streamed value.
+		if (var_opt_optimize_init[i]) {
+			print "  if (" var_opt_optimize_init[i] " > (" var_opt_val_type[i] ") 10)";
+			print "    bp_pack_var_len_" sgn " (bp, ptr->" name" ^ " var_opt_optimize_init[i] ");";
 			print "  else";
 			print "    bp_pack_var_len_" sgn " (bp, ptr->" name");";
 		} else {
@@ -1406,9 +1422,10 @@ for (i = 0; i < n_opt_val; i++) {
 			sgn = "int";
 		}
 		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_" sgn " (bp);";
-		if (name ~ "^x_param" && !(otype ~ "^enum ") && var_opt_init[i]) {
-			print "  if (" var_opt_init[i] " > (" var_opt_val_type[i] ") 10)";
-			print "    ptr->" name" ^= " var_opt_init[i] ";";
+		# If applicable, decode the streamed value.
+		if (var_opt_optimize_init[i]) {
+			print "  if (" var_opt_optimize_init[i] " > (" var_opt_val_type[i] ") 10)";
+			print "    ptr->" name" ^= " var_opt_optimize_init[i] ";";
 		}
 	}
 }
-- 
2.35.1

Re: [PING] options: Clarify 'Init' option property usage for streaming optimization (was: [PATCH] options, lto: Optimize streaming of optimization nodes)

[Joseph Myers]

On Wed, 26 Oct 2022, Thomas Schwinge wrote:

> Hi!
> 
> Ping.  For convenience, I've re-attached
> "options: Clarify 'Init' option property usage for streaming optimization".
> (I've re-verified: "No functional change; no change in generated files.")

OK.

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: [PATCH] options, lto: Optimize streaming of optimization nodes

[Richard Biener]

On Mon, 14 Sep 2020, Jakub Jelinek wrote:

> On Mon, Sep 14, 2020 at 09:31:52AM +0200, Richard Biener wrote:
> > But does it make any noticable difference in the end?  Using
> 
> Yes.
> 
> > bp_pack_var_len_unsigned just causes us to [u]leb encode half-bytes
> > rather than full bytes.  Using hardcoded 8/16/32/64 makes it still
> > dependent on what 'int' is at maximum on the host.
> > 
> > That is, I'd indeed prefer bp_pack_var_len_unsigned over hard-coding
> > 8, 16, etc., but can you share a size comparison of the bitpack?
> > I guess with bp_pack_var_len_unsigned it might shrink in half
> > compared to the current code and streaming standard -O2?
> 
> So, I've tried
> --- gcc/tree-streamer-out.c.jj	2020-07-28 15:39:10.079755251 +0200
> +++ gcc/tree-streamer-out.c	2020-09-14 10:31:29.106957258 +0200
> @@ -489,7 +489,11 @@ streamer_write_tree_bitfields (struct ou
>      pack_ts_translation_unit_decl_value_fields (ob, &bp, expr);
>  
>    if (CODE_CONTAINS_STRUCT (code, TS_OPTIMIZATION))
> +{
> +long ts = ob->main_stream->total_size;
>      cl_optimization_stream_out (ob, &bp, TREE_OPTIMIZATION (expr));
> +fprintf (stderr, "total_size %ld\n", (long) (ob->main_stream->total_size - ts));
> +}
>  
>    if (CODE_CONTAINS_STRUCT (code, TS_CONSTRUCTOR))
>      bp_pack_var_len_unsigned (&bp, CONSTRUCTOR_NELTS (expr));
> hack without and with the following patch on a simple small testcase with
> -O2 -flto.
> Got 574 bytes without the opc-save-gen.awk change and 454 bytes with it,
> that is ~ 21% saving on the TREE_OPTIMIZATION streaming.

OK, not spectacular but I guess good enough.  So I'd say the below
patch using bp_pack_var_len_{int,unsigned} is OK.

Thanks,
Richard.

> 2020-09-14  Jakub Jelinek  <jakub@redhat.com>
> 
> 	* optc-save-gen.awk: In cl_optimization_stream_out use
> 	bp_pack_var_len_{int,unsigned} instead of bp_pack_value.  In
> 	cl_optimization_stream_in use bp_unpack_var_len_{int,unsigned}
> 	instead of bp_unpack_value.  Formatting fix.
> 
> --- gcc/optc-save-gen.awk.jj	2020-09-14 09:04:35.879854156 +0200
> +++ gcc/optc-save-gen.awk	2020-09-14 10:38:47.722424942 +0200
> @@ -1257,8 +1257,10 @@ for (i = 0; i < n_opt_val; i++) {
>  	otype = var_opt_val_type[i];
>  	if (otype ~ "^const char \\**$")
>  		print "  bp_pack_string (ob, bp, ptr->" name", true);";
> +	else if (otype ~ "^unsigned")
> +		print "  bp_pack_var_len_unsigned (bp, ptr->" name");";
>  	else
> -		print "  bp_pack_value (bp, ptr->" name", 64);";
> +		print "  bp_pack_var_len_int (bp, ptr->" name");";
>  }
>  print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
>  print "    bp_pack_value (bp, ptr->explicit_mask[i], 64);";
> @@ -1274,14 +1276,15 @@ print "{";
>  for (i = 0; i < n_opt_val; i++) {
>  	name = var_opt_val[i]
>  	otype = var_opt_val_type[i];
> -	if (otype ~ "^const char \\**$")
> -	{
> -	      print "  ptr->" name" = bp_unpack_string (data_in, bp);";
> -	      print "  if (ptr->" name")";
> -	      print "    ptr->" name" = xstrdup (ptr->" name");";
> +	if (otype ~ "^const char \\**$") {
> +		print "  ptr->" name" = bp_unpack_string (data_in, bp);";
> +		print "  if (ptr->" name")";
> +		print "    ptr->" name" = xstrdup (ptr->" name");";
>  	}
> +	else if (otype ~ "^unsigned")
> +		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_unsigned (bp);";
>  	else
> -	      print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_value (bp, 64);";
> +		print "  ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_var_len_int (bp);";
>  }
>  print "  for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof (ptr->explicit_mask[0]); i++)";
>  print "    ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";
> 
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)