From ec620387afc9779929628bc497fed27017b34cd7 Mon Sep 17 00:00:00 2001
From: Todd Strader <todd.strader@gmail.com>
Date: Tue, 27 Aug 2019 21:36:59 -0400
Subject: [PATCH] Add --dpi-hdr-only, bug1491.

---
 Changes                                 |  2 ++
 bin/verilator                           |  6 ++++
 src/V3EmitC.h                           |  2 +-
 src/V3EmitCSyms.cpp                     | 17 ++++++----
 src/V3Options.cpp                       |  2 ++
 src/V3Options.h                         |  2 ++
 src/Verilator.cpp                       | 17 +++++++---
 test_regress/driver.pl                  |  5 +++
 test_regress/t/t_dpi_import_hdr_only.pl | 45 +++++++++++++++++++++++++
 9 files changed, 86 insertions(+), 12 deletions(-)
 create mode 100755 test_regress/t/t_dpi_import_hdr_only.pl

diff --git a/Changes b/Changes
index 4da553b37..ba0a9420f 100644
--- a/Changes
+++ b/Changes
@@ -26,6 +26,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Fix internal error on gate optimization of assign, bug1475. [Oyvind Harboe]
 
+****  Add --dpi-hdr-only, bug1491. [Todd Strader]
+
 
 * Verilator 4.016 2019-06-16
 
diff --git a/bin/verilator b/bin/verilator
index d935ce1e3..f014f2d37 100755
--- a/bin/verilator
+++ b/bin/verilator
@@ -298,6 +298,7 @@ detailed descriptions in L</"VERILATION ARGUMENTS"> for more information.
     --debugi-<srcfile> <level>  Enable debugging a source file at a level
     --default-language <lang>   Default language to parse
      +define+<var>=<value>      Set preprocessor define
+    --dpi-hdr-only              Only produce the DPI header file
     --dump-defines              Show preprocessor defines with -E
     --dump-tree                 Enable dumping .tree files
     --dump-treei <level>        Enable dumping .tree files at a level
@@ -741,6 +742,11 @@ Defines the given preprocessor symbol, or multiple symbols if separated by
 plusses.  Similar to -D; +define is fairly standard across Verilog tools
 while -D is an alias for GCC compatibility.
 
+=item --dpi-hdr-only
+
+Only generate the DPI header file.  This option has no effect on the name
+or location of the file.
+
 =item --dump-defines
 
 With -E, suppress normal output, and instead print a list of all defines
diff --git a/src/V3EmitC.h b/src/V3EmitC.h
index c7b878814..a509526e5 100644
--- a/src/V3EmitC.h
+++ b/src/V3EmitC.h
@@ -33,7 +33,7 @@ class V3EmitC {
 public:
     static void emitc();
     static void emitcInlines();
-    static void emitcSyms();
+    static void emitcSyms(bool dpiHdrOnly = false);
     static void emitcTrace();
 };
 
diff --git a/src/V3EmitCSyms.cpp b/src/V3EmitCSyms.cpp
index 06f0cd226..55975a69c 100644
--- a/src/V3EmitCSyms.cpp
+++ b/src/V3EmitCSyms.cpp
@@ -90,6 +90,7 @@ class EmitCSyms : EmitCBaseVisitor {
     V3LanguageWords     m_words;        // Reserved word detector
     int         m_coverBins;            // Coverage bin number
     int         m_labelNum;             // Next label number
+    bool        m_dpiHdrOnly;           // Only emit the DPI header
 
     // METHODS
     void emitSymHdr();
@@ -181,11 +182,13 @@ class EmitCSyms : EmitCBaseVisitor {
         stable_sort(m_dpis.begin(), m_dpis.end(), CmpDpi());
 
         // Output
-        emitSymHdr();
-        emitSymImp();
+        if (!m_dpiHdrOnly) {
+            emitSymHdr();
+            emitSymImp();
+        }
         if (v3Global.dpi()) {
             emitDpiHdr();
-            emitDpiImp();
+            if (!m_dpiHdrOnly) emitDpiImp();
         }
     }
     virtual void visit(AstNodeModule* nodep) {
@@ -253,7 +256,9 @@ class EmitCSyms : EmitCBaseVisitor {
     //---------------------------------------
     // ACCESSORS
 public:
-    explicit EmitCSyms(AstNetlist* nodep) {
+    explicit EmitCSyms(AstNetlist* nodep, bool dpiHdrOnly):
+        m_dpiHdrOnly(dpiHdrOnly)
+    {
         m_funcp = NULL;
         m_modp = NULL;
         m_coverBins = 0;
@@ -661,7 +666,7 @@ void EmitCSyms::emitDpiImp() {
 //######################################################################
 // EmitC class functions
 
-void V3EmitC::emitcSyms() {
+void V3EmitC::emitcSyms(bool dpiHdrOnly) {
     UINFO(2,__FUNCTION__<<": "<<endl);
-    EmitCSyms syms (v3Global.rootp());
+    EmitCSyms syms (v3Global.rootp(), dpiHdrOnly);
 }
diff --git a/src/V3Options.cpp b/src/V3Options.cpp
index d03009055..b5f71eccd 100644
--- a/src/V3Options.cpp
+++ b/src/V3Options.cpp
@@ -677,6 +677,7 @@ void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc, char
             else if (!strcmp(sw, "-debug-sigsegv"))             { throwSigsegv(); }  // Undocumented, see also --debug-abort
             else if (!strcmp(sw, "-debug-fatalsrc"))            { v3fatalSrc("--debug-fatal-src"); }  // Undocumented, see also --debug-abort
             else if ( onoff (sw, "-decoration", flag/*ref*/))   { m_decoration = flag; }
+            else if ( onoff (sw, "-dpi-hdr-only", flag/*ref*/)) { m_dpiHdrOnly = flag; }
             else if ( onoff (sw, "-dump-defines", flag/*ref*/)) { m_dumpDefines = flag; }
             else if ( onoff (sw, "-dump-tree", flag/*ref*/))    { m_dumpTree = flag ? 3 : 0; }  // Also see --dump-treei
             else if ( onoff (sw, "-exe", flag/*ref*/))          { m_exe = flag; }
@@ -1276,6 +1277,7 @@ V3Options::V3Options() {
     m_debugPartition = false;
     m_debugSelfTest = false;
     m_decoration = true;
+    m_dpiHdrOnly = false;
     m_dumpDefines = false;
     m_exe = false;
     m_ignc = false;
diff --git a/src/V3Options.h b/src/V3Options.h
index c7b90d32e..01c4b9bad 100644
--- a/src/V3Options.h
+++ b/src/V3Options.h
@@ -120,6 +120,7 @@ class V3Options {
     bool        m_debugPartition;  // main switch: --debug-partition
     bool        m_debugSelfTest;  // main switch: --debug-self-test
     bool        m_decoration;   // main switch: --decoration
+    bool        m_dpiHdrOnly;   // main switch: --dpi-hdr-only
     bool        m_dumpDefines;  // main switch: --dump-defines
     bool        m_exe;          // main switch: --exe
     bool        m_ignc;         // main switch: --ignc
@@ -287,6 +288,7 @@ class V3Options {
     bool debugPartition() const { return m_debugPartition; }
     bool debugSelfTest() const { return m_debugSelfTest; }
     bool decoration() const { return m_decoration; }
+    bool dpiHdrOnly() const { return m_dpiHdrOnly; }
     bool dumpDefines() const { return m_dumpDefines; }
     bool exe() const { return m_exe; }
     bool threadsDpiPure() const { return m_threadsDpiPure; }
diff --git a/src/Verilator.cpp b/src/Verilator.cpp
index 614389728..f80068109 100644
--- a/src/Verilator.cpp
+++ b/src/Verilator.cpp
@@ -519,11 +519,14 @@ void process() {
 
     // Output the text
     if (!v3Global.opt.lintOnly()
-        && !v3Global.opt.xmlOnly()) {
+        && !v3Global.opt.xmlOnly()
+        && !v3Global.opt.dpiHdrOnly()) {
         // emitcInlines is first, as it may set needHInlines which other emitters read
         V3EmitC::emitcInlines();
         V3EmitC::emitcSyms();
         V3EmitC::emitcTrace();
+    } else if (v3Global.opt.dpiHdrOnly()) {
+        V3EmitC::emitcSyms(true);
     }
     if (!v3Global.opt.xmlOnly()
         && v3Global.opt.mtasks()) {
@@ -533,12 +536,14 @@ void process() {
         // costs of mtasks.
         V3Partition::finalize();
     }
-    if (!v3Global.opt.xmlOnly()) {  // Unfortunately we have some lint checks in emitc.
+    if (!v3Global.opt.xmlOnly()
+        && !v3Global.opt.dpiHdrOnly()) {  // Unfortunately we have some lint checks in emitc.
         V3EmitC::emitc();
     }
     if (v3Global.opt.xmlOnly()
         // Check XML when debugging to make sure no missing node types
-        || (v3Global.opt.debugCheck() && !v3Global.opt.lintOnly())) {
+        || (v3Global.opt.debugCheck() && !v3Global.opt.lintOnly()
+            && !v3Global.opt.dpiHdrOnly())) {
         V3EmitXml::emitxml();
     }
 
@@ -549,7 +554,8 @@ void process() {
     }
 
     if (!v3Global.opt.lintOnly()
-        && !v3Global.opt.xmlOnly()) {
+        && !v3Global.opt.xmlOnly()
+        && !v3Global.opt.dpiHdrOnly()) {
         // Makefile must be after all other emitters
         V3EmitMk::emitmk(v3Global.rootp());
     }
@@ -633,10 +639,11 @@ int main(int argc, char** argv, char** env) {
     V3Error::abortIfWarnings();
 
     if (!v3Global.opt.lintOnly() && !v3Global.opt.cdc()
-        && v3Global.opt.makeDepend()) {
+        && !v3Global.opt.dpiHdrOnly() && v3Global.opt.makeDepend()) {
         V3File::writeDepend(v3Global.opt.makeDir()+"/"+v3Global.opt.prefix()+"__ver.d");
     }
     if (!v3Global.opt.lintOnly() && !v3Global.opt.cdc()
+        && !v3Global.opt.dpiHdrOnly()
         && (v3Global.opt.skipIdentical() || v3Global.opt.makeDepend())) {
         V3File::writeTimes(v3Global.opt.makeDir()+"/"+v3Global.opt.prefix()
                            +"__verFiles.dat", argString);
diff --git a/test_regress/driver.pl b/test_regress/driver.pl
index 1c5af8b73..a4c372415 100755
--- a/test_regress/driver.pl
+++ b/test_regress/driver.pl
@@ -1201,6 +1201,11 @@ sub trace_filename {
     return "$self->{obj_dir}/simx.vcd";
 }
 
+sub obj_dir {
+    my $self = shift;
+    return $self->{obj_dir};
+}
+
 sub get_default_vltmt_threads {
     return $Vltmt_threads;
 }
diff --git a/test_regress/t/t_dpi_import_hdr_only.pl b/test_regress/t/t_dpi_import_hdr_only.pl
new file mode 100755
index 000000000..d89c46dd8
--- /dev/null
+++ b/test_regress/t/t_dpi_import_hdr_only.pl
@@ -0,0 +1,45 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2019 by Todd Strader. This program is free software; you can
+# redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+
+use File::Temp;
+use File::Compare;
+
+scenarios(simulator => 1);
+
+top_filename("t/t_dpi_import.v");
+
+my $tmp_dir = File::Temp->newdir();
+
+compile(
+    verilator_flags2 => ["-Wall -Wno-DECLFILENAME -Mdir " . $tmp_dir . " --dpi-hdr-only"],
+    verilator_make_gcc => 0,
+    );
+
+my @files = glob($tmp_dir . "/*");
+
+die "Did not produce DPI header" if scalar(@files) == 0;
+die "Too many files created" if scalar(@files) > 1;
+my $tmp_header = $files[0];
+print("============".$tmp_header."\n");
+die "Unexpected file $tmp_header" unless $tmp_header =~ /__Dpi\.h$/;
+
+compile(
+    verilator_flags2 => ["-Wall -Wno-DECLFILENAME"],
+    verilator_make_gcc => 0,
+    );
+
+@files = glob($Self->obj_dir . "/*__Dpi.h");
+my $header = @files[0];
+
+if (compare($tmp_header, $header) != 0) {
+    die "DPI header files are not the same";
+}
+
+ok(1);
+1;