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

[Jakub Jelinek <jakub@redhat.com>]

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