Support split_var in vit files (#2219)

Changes

@@ -13,6 +13,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Suppress REALCVT for whole real numbers.
 
+****  Support split_var in vlt files, #2219. [Marco Widmer]
+
 ****  Fix parameter type redeclaring a type, #2195. [hdzhangdoc]
 
 ****  Fix VCD open with empty filename, #2198. [Julius Baxter]

bin/verilator

@@ -2971,6 +2971,17 @@ behavior.  See the test_regress/t/t_dpi_display.v file for an example.
 Same as /*verilator sformat*/, see L</"LANGUAGE EXTENSIONS"> for more
 information.
 
+=item split_var [-module "<modulename>"] [-task "<taskname>"] -var "<varname>"
+
+=item split_var [-module "<modulename>"] [-function "<funcname>"] -var "<varname>"
+
+Break the variable into multiple pieces typically to resolve UNOPTFLAT
+performance issues. Typically the variables to attach this to are
+recommeded by Verilator itself, see UNOPTFLAT.
+
+Same as /*verilator split_var*/, see L</"LANGUAGE EXTENSIONS"> for more
+information.
+
 =back
 
 
@@ -3484,6 +3495,9 @@ requested but cannot occur a SPLITVAR warning is issued.  Splitting large
 arrays may slow donw the Verilation speed, so use this only on variables
 that require it.
 
+Same as C<split_var> in configuration files, see L</"CONFIGURATION FILES">
+for more information.
+
 =item /*verilator tag <text...>*/
 
 Attached after a variable or structure member to indicate opaque (to

src/verilog.l

@@ -151,6 +151,7 @@ vnum    {vnum1}|{vnum2}|{vnum3}|{vnum4}|{vnum5}
   "public_module"       { FL; return yVLT_PUBLIC_MODULE; }
   "sc_bv"               { FL; return yVLT_SC_BV; }
   "sformat"             { FL; return yVLT_SFORMAT; }
+  "split_var"           { FL; return yVLT_SPLIT_VAR; }
   "tracing_off"         { FL; return yVLT_TRACING_OFF; }
   "tracing_on"          { FL; return yVLT_TRACING_ON; }
 

src/verilog.y

@@ -291,6 +291,7 @@ class AstSenTree;
 %token<fl>		yVLT_PUBLIC_MODULE          "public_module"
 %token<fl>		yVLT_SC_BV                  "sc_bv"
 %token<fl>		yVLT_SFORMAT                "sformat"
+%token<fl>		yVLT_SPLIT_VAR              "split_var"
 %token<fl>		yVLT_TRACING_OFF            "tracing_off"
 %token<fl>		yVLT_TRACING_ON             "tracing_on"
 
@@ -5824,6 +5825,7 @@ vltVarAttrFront<attrtypeen>:
 	|	yVLT_PUBLIC_FLAT_RW         { $$ = AstAttrType::VAR_PUBLIC_FLAT_RW; v3Global.dpi(true); }
 	|	yVLT_SC_BV                  { $$ = AstAttrType::VAR_SC_BV; }
 	|	yVLT_SFORMAT                { $$ = AstAttrType::VAR_SFORMAT; }
+	|	yVLT_SPLIT_VAR              { $$ = AstAttrType::VAR_SPLIT_VAR; }
 	;
 
 //**********************************************************************

test_regress/t/t_split_var_0.pl

@@ -14,7 +14,8 @@ scenarios(simulator => 1);
 # %Warning-UNOPTTHREADS: Thread scheduler is unable to provide requested parallelism; consider asking for fewer threads.
 # So use 6 threads here though it's not optimal in performace wise, but ok.
 compile(
-    verilator_flags2 => ['--stats' . ($Self->{vltmt} ? ' --threads 6' : '')],
+    verilator_flags2 => ['--stats' . ($Self->{vltmt} ? ' --threads 6' : ''),
+                         "$Self->{t_dir}/t_split_var_0.vlt"],
     );
 
 execute(

test_regress/t/t_split_var_0.v

@@ -10,7 +10,11 @@ module barshift_1d_unpacked #(parameter DEPTH = 2, localparam WIDTH = 2**DEPTH)
    (input [WIDTH-1:0] in, input [DEPTH-1:0] shift, output [WIDTH-1:0] out /*verilator split_var*/);
 
    localparam OFFSET = -3;
+`ifdef TEST_ATTRIBUTES
    logic [WIDTH-1:0] tmp[DEPTH+OFFSET:OFFSET] /*verilator split_var*/;
+`else
+   logic [WIDTH-1:0] tmp[DEPTH+OFFSET:OFFSET];
+`endif
    generate
       for(genvar i = 0; i < DEPTH; ++i) begin
          always_comb

test_regress/t/t_split_var_0.vlt

@@ -0,0 +1,9 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2020 by Marco Widmer.
+// SPDX-License-Identifier: CC0-1.0
+
+`verilator_config
+
+split_var -module "barshift_1d_unpacked" -var "tmp"

test_regress/t/t_split_var_2_trace.pl

@@ -15,7 +15,8 @@ top_filename("t/t_split_var_0.v");
 # %Warning-UNOPTTHREADS: Thread scheduler is unable to provide requested parallelism; consider asking for fewer threads.
 # So use 6 threads here though it's not optimal in performace wise, but ok.
 compile(
-    verilator_flags2 => ['--cc --trace --stats' . ($Self->{vltmt} ? ' --threads 6' : '')],
+    verilator_flags2 => ['--cc --trace --stats' . ($Self->{vltmt} ? ' --threads 6' : ''),
+                         '+define+TEST_ATTRIBUTES'],
     );
 
 execute(