Add assertions on 'unique if', bug725.

Changes

@@ -9,6 +9,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ***   Add --no-trace-params.
 
+***   Add assertions on 'unique if', bug725. [Jeff Bush] 
+
 ****  Documentation fixes, bug723. [Glen Gibb]
 
 ****  Fix tracing of package variables and real arrays.

bin/verilator

@@ -1991,9 +1991,8 @@ appropriate code to detect failing cases at runtime and print an "Assertion
 failed" error message.
 
 Verilator likewise also asserts any "unique" or "priority" SystemVerilog
-keywords on case statements.  However, "unique if" and "priority if" are
+keywords on case statement, as well as "unique" on if statements.
-currently simply ignored.
+However, "priority if" is currently simply ignored.
-
 
 =head1 LANGUAGE EXTENSIONS
 

src/V3Assert.cpp

@@ -175,6 +175,61 @@ private:
 	pushDeletep(nodep); nodep=NULL;
     }
     
+    virtual void visit(AstIf* nodep, AstNUser*) {
+	if (nodep->uniquePragma() || nodep->unique0Pragma()) {
+	    AstNodeIf* ifp = nodep;
+	    AstNode* propp = NULL;
+	    bool hasDefaultElse = false;
+	    do {
+		// If this statement ends with 'else if', then nextIf will point to the
+		// nextIf statement.  Otherwise it will be null.
+		AstNodeIf* nextifp = dynamic_cast<AstNodeIf*>(ifp->elsesp());
+
+		// Recurse into the true case.
+		ifp->ifsp()->iterateChildren(*this);
+		
+		// If the last else is not an else if, recurse into that too.
+		if (ifp->elsesp() && !nextifp) {
+		    ifp->elsesp()->iterateChildren(*this);
+		}
+		
+		// Build a bitmask of the true predicates
+	        AstNode* predp = ifp->condp()->cloneTree(false);
+	        if (propp) {
+		    propp = new AstConcat(nodep->fileline(), predp, propp);
+		} else {
+		    propp = predp;
+		}
+
+		// Record if this ends with an 'else' that does not have an if
+		if (ifp->elsesp() && !nextifp) {
+		    hasDefaultElse = true;
+		}
+		
+		ifp = nextifp;
+	    } while (ifp);
+
+	    AstNode *newifp = nodep->cloneTree(false);
+	    bool allow_none = nodep->unique0Pragma();
+	    
+	    // Note: if this ends with an 'else', then we don't need to validate that one of the
+	    // predicates evaluates to true.
+	    AstNode* ohot = ((allow_none || hasDefaultElse)
+			     ? (new AstOneHot0(nodep->fileline(), propp))->castNode()
+			     : (new AstOneHot (nodep->fileline(), propp))->castNode());
+	    AstIf* checkifp = new AstIf (nodep->fileline(),
+					 new AstLogNot (nodep->fileline(), ohot),
+					 newFireAssert(nodep, "'unique if' statement violated"),
+					 newifp);
+	    checkifp->branchPred(AstBranchPred::BP_UNLIKELY);
+	    nodep->replaceWith(checkifp);
+	    pushDeletep(nodep);
+	} else {
+	    nodep->ifsp()->iterateChildren(*this);
+	    nodep->elsesp()->iterateChildren(*this);
+	}
+    }
+
     // VISITORS  //========== Case assertions
     virtual void visit(AstCase* nodep, AstNUser*) {
 	nodep->iterateChildren(*this);

test_regress/t/t_uniqueif.pl

@@ -0,0 +1,20 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003-2009 by Wilson Snyder. 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.
+
+compile (
+    verilator_flags2 => ['--assert'],
+    nc_flags2 => ['+assert'],
+    );
+
+execute (
+    check_finished=>1,
+    );
+
+ok(1);
+1;

test_regress/t/t_uniqueif.v

@@ -0,0 +1,111 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2007 by Wilson Snyder.
+
+module t (/*AUTOARG*/
+   // Inputs
+   clk
+   );
+
+   input clk;
+
+   integer cyc=1;
+   integer a, b, c, d, e, f, g, h, i, j, k, l;
+
+   always @ (posedge clk) begin
+      cyc <= cyc + 1;
+
+      //====================
+      // Positive test cases
+      //====================
+
+      // Single if, which is untrue sometimes
+      unique0 if (cyc > 5)
+	a <= 17;
+
+      // single if with else
+      unique0 if (cyc < 3)
+	b <= 17;
+      else
+	b <= 19;
+
+      // multi if, some cases may not be true
+      unique0 if (cyc < 3)
+	c <= 17;
+      else if (cyc > 3)
+	c <= 19;
+
+      // multi if with else, else clause hit in some cases
+      unique0 if (cyc < 3)
+	d <= 17;
+      else if (cyc > 3)
+	d <= 19;
+      else
+	d <= 21;
+
+      // single if with else
+      unique if (cyc < 3)
+	f <= 17;
+      else
+	f <= 19;
+
+      // multi if
+      unique if (cyc < 3)
+	g <= 17;
+      else if (cyc >= 3)
+	g <= 19;
+
+      // multi if with else, else clause hit in some cases
+      unique if (cyc < 3)
+	h <= 17;
+      else if (cyc > 3)
+	h <= 19;
+      else
+	h <= 21;
+
+      //====================
+      // Negative test cases
+      //====================
+`ifdef FAILING_ASSERTION1
+      $display("testing fail 1: %d", cyc);
+      // multi if, multiple cases true
+      unique0 if (cyc < 3)
+	i <= 17;
+      else if (cyc < 5)
+	i <= 19;
+`endif
+
+`ifdef FAILING_ASSERTION2
+      // multi if, multiple cases true
+      unique if (cyc < 3)
+	j <= 17;
+      else if (cyc < 5)
+	j <= 19;
+`endif
+
+`ifdef FAILING_ASSERTION3
+      // multi if, no cases true
+      unique if (cyc > 1000)
+	k <= 17;
+      else if (cyc > 2000)
+	k <= 19;
+`endif
+
+`ifdef FAILING_ASSERTION4
+      // Single if, which is untrue sometimes.
+      // The LRM states: "A software tool shall also issue an error if it determines that no condition'
+      // is true, or it is possible that no condition is true, and the final if does not have a
+      // corresponding else."  In this case, the final if is the only if, but I think the clause
+      // still applies.
+      unique if (cyc > 5)
+	l <= 17;
+`endif
+
+
+      if (cyc==10) begin
+	 $write("*-* All Finished *-*\n");
+	 $finish;
+      end
+   end
+endmodule

test_regress/t/t_uniqueif_fail1.pl

@@ -0,0 +1,28 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003-2009 by Wilson Snyder. 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.
+
+top_filename("t/t_uniqueif.v");
+
+compile (
+    v_flags2 => ['+define+FAILING_ASSERTION1'],
+    verilator_flags2 => ['--assert'],
+    nc_flags2 => ['+assert'],
+    fails => $Self->{nc},
+    );
+
+execute (
+    fails => $Self->{vlt},
+    expect=>
+'.*%Error: t_uniqueif.v:\d+: Assertion failed in top.v: \'unique if\' statement violated
+%Error: t/t_uniqueif.v:\d+: Verilog \$stop
+.*',
+    );
+
+ok(1);
+1;

test_regress/t/t_uniqueif_fail2.pl

@@ -0,0 +1,28 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003-2009 by Wilson Snyder. 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.
+
+top_filename("t/t_uniqueif.v");
+
+compile (
+    v_flags2 => ['+define+FAILING_ASSERTION2'],
+    verilator_flags2 => ['--assert'],
+    nc_flags2 => ['+assert'],
+    fails => $Self->{nc},
+    );
+
+execute (
+    fails => $Self->{vlt},
+    expect=>
+'.*%Error: t_uniqueif.v:\d+: Assertion failed in top.v: \'unique if\' statement violated
+%Error: t/t_uniqueif.v:\d+: Verilog \$stop
+.*',
+    );
+
+ok(1);
+1;

test_regress/t/t_uniqueif_fail3.pl

@@ -0,0 +1,28 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003-2009 by Wilson Snyder. 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.
+
+top_filename("t/t_uniqueif.v");
+
+compile (
+    v_flags2 => ['+define+FAILING_ASSERTION3'],
+    verilator_flags2 => ['--assert'],
+    nc_flags2 => ['+assert'],
+    fails => $Self->{nc},
+    );
+
+execute (
+    fails => $Self->{vlt},
+    expect=>
+'.*%Error: t_uniqueif.v:\d+: Assertion failed in top.v: \'unique if\' statement violated
+%Error: t/t_uniqueif.v:\d+: Verilog \$stop
+.*',
+    );
+
+ok(1);
+1;

test_regress/t/t_uniqueif_fail4.pl

@@ -0,0 +1,28 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003-2009 by Wilson Snyder. 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.
+
+top_filename("t/t_uniqueif.v");
+
+compile (
+    v_flags2 => ['+define+FAILING_ASSERTION4'],
+    verilator_flags2 => ['--assert'],
+    nc_flags2 => ['+assert'],
+    fails => $Self->{nc},
+    );
+
+execute (
+    fails => $Self->{vlt},
+    expect=>
+'.*%Error: t_uniqueif.v:\d+: Assertion failed in top.v: \'unique if\' statement violated
+%Error: t/t_uniqueif.v:\d+: Verilog \$stop
+.*',
+    );
+
+ok(1);
+1;