Fix dist inside a foreach nested in a constraint if (#8016)
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BRDR LIFE
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parent
704c5a1c96
commit
6b3aebfa32
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@ -1176,6 +1176,17 @@ class ConstraintExprVisitor final : public VNVisitor {
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nodep->user1(anyChild);
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}
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// Prepend the bucket preamble stmts stored on user3p by lowerDistConstraints to the
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// statements that will become the body of the generated AstForeach, so the per-element
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// bucket draw is declared and evaluated in the same scope as its references.
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static AstNode* prependDistPreamble(AstConstraintForeach* nodep, AstNode* bodyp) {
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AstNode* const preamblep = nodep->user3p();
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if (!preamblep) return bodyp;
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nodep->user3p(nullptr);
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preamblep->addNext(bodyp);
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return preamblep;
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}
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// VISITORS
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void visit(AstNodeVarRef* nodep) override {
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AstVar* varp = nodep->varp();
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@ -2306,25 +2317,22 @@ class ConstraintExprVisitor final : public VNVisitor {
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cstmtp->add("ret += ");
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cstmtp->add(itemp);
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cstmtp->add(";");
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AstNode* const bodyp = prependDistPreamble(nodep, cstmtp);
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AstCExpr* const cexprp = new AstCExpr{fl};
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cexprp->dtypeSetString();
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cexprp->add("([&]{\nstd::string ret;\n");
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cexprp->add(new AstBegin{
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fl, "", new AstForeach{fl, nodep->headerp()->unlinkFrBack(), cstmtp}, true});
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fl, "", new AstForeach{fl, nodep->headerp()->unlinkFrBack(), bodyp}, true});
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cexprp->add("return ret.empty() ? \"#b1\" : \"(bvand\" + ret + \")\";\n})()");
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nodep->replaceWith(new AstSFormatF{fl, "%s", false, cexprp});
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} else {
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iterateAndNextNull(nodep->bodyp());
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AstNode* bodyp = nodep->bodyp()->unlinkFrBackWithNext();
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// Prepend bucket preamble stmts stored by lowerDistConstraints (foreach case)
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if (AstNode* const preamblep = nodep->user3p()) {
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preamblep->addNext(bodyp);
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bodyp = preamblep;
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nodep->user3p(nullptr);
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}
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AstNode* const bodyp
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= prependDistPreamble(nodep, nodep->bodyp()->unlinkFrBackWithNext());
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nodep->replaceWith(new AstBegin{
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fl, "", new AstForeach{fl, nodep->headerp()->unlinkFrBack(), bodyp}, true});
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}
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UASSERT_OBJ(!nodep->user3p(), nodep, "Dist bucket preamble not injected into foreach");
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VL_DO_DANGLING(nodep->deleteTree(), nodep);
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}
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void visit(AstConstraintBefore* nodep) override {
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@ -0,0 +1,21 @@
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#!/usr/bin/env python3
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# DESCRIPTION: Verilator: Verilog Test driver/expect definition
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#
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# This program is free software; you can redistribute it and/or modify it
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# under the terms of either the GNU Lesser General Public License Version 3
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# or the Perl Artistic License Version 2.0.
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# SPDX-FileCopyrightText: 2026 Wilson Snyder
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# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
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import vltest_bootstrap
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test.scenarios('simulator')
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if not test.have_solver:
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test.skip("No constraint solver installed")
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test.compile()
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test.execute()
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test.passes()
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@ -0,0 +1,493 @@
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// DESCRIPTION: Verilator: Verilog Test module
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//
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// This file ONLY is placed under the Creative Commons Public Domain.
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// SPDX-FileCopyrightText: 2026 BRDR LIFE
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// SPDX-License-Identifier: CC0-1.0
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// Test that a dist constraint inside a foreach nested within a constraint if
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// produces values only within the declared distribution, covers all buckets,
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// honors the declared weights, and draws a bucket per array element.
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// verilog_format: off
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`define stop $stop
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`define checkd(gotv,expv) do if ((gotv) !== (expv)) begin \
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$write("%%Error: %s:%0d: got=%0d exp=%0d\n", `__FILE__, `__LINE__, (gotv), (expv)); `stop; end while(0)
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`define checkgt(gotv,minv) do if (!((gotv) > (minv))) begin \
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$write("%%Error: %s:%0d: got=%0d expected > %0d\n", `__FILE__, `__LINE__, (gotv), (minv)); `stop; end while(0)
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// verilog_format: on
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// if (gate) foreach (a[i]) a[i] dist {...}
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class ClsIf;
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rand bit [3:0] a[4];
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bit gate;
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constraint c {
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if (gate == 1'b1) {
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foreach (a[i]) {
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a[i] dist {
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4'd0 := 3,
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[4'd1 : 4'd4] := 1
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};
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}
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}
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}
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endclass
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// if (gate) foreach (a[i]) a[i] dist {...} else foreach (a[i]) a[i] dist {...}
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class ClsIfElse;
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rand bit [3:0] a[4];
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bit gate;
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constraint c {
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if (gate == 1'b1) {
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foreach (a[i]) {
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a[i] dist {
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4'd0 := 3,
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[4'd1 : 4'd4] := 1
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};
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}
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} else {
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foreach (a[i]) {a[i] dist {[4'd8 : 4'd11] := 1};}
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}
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}
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endclass
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// if (gate) foreach (a[i]) gate2 -> a[i] dist {...}
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class ClsIfImpl;
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rand bit [3:0] a[4];
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bit gate, gate2;
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constraint c {
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if (gate == 1'b1) {
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foreach (a[i]) {
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gate2 ->
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(a[i] dist {
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4'd0 := 3,
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[4'd1 : 4'd4] := 1
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});
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}
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}
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}
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endclass
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// if (sel) foreach (a[i]) a[i] dist {...}, with a randomized condition
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class ClsRandSel;
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rand bit [2:0] a[4];
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rand bit sel;
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constraint c {
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if (sel) {
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foreach (a[i]) {
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a[i] dist {
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[3'd0 : 3'd1] :/ 90,
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[3'd2 : 3'd5] :/ 10
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};
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}
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}
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}
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endclass
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// Two dist constraints sharing one foreach body inside a constraint if
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class ClsMulti;
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rand bit [2:0] a[4];
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rand bit [2:0] b[4];
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bit gate;
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constraint c {
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if (gate == 1'b1) {
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foreach (a[i]) {
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a[i] dist {
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[3'd0 : 3'd1] :/ 90,
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[3'd2 : 3'd5] :/ 10
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};
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b[i] dist {3'd7 := 1};
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}
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}
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}
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endclass
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// if (gate) foreach (m[i]) foreach (m[i][j]) m[i][j] dist {...}
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class ClsNested;
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rand bit [2:0] m[2][2];
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bit gate;
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constraint c {
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if (gate == 1'b1) {
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foreach (m[i]) {
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foreach (m[i][j]) {
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m[i][j] dist {
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[3'd0 : 3'd1] :/ 90,
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[3'd2 : 3'd5] :/ 10
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};
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}
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}
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}
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}
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endclass
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// Two equally weighted, non-adjacent buckets, so a per-element bucket draw is
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// observable as differing elements within a single randomize() call
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class ClsIndep;
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rand bit [3:0] a[8];
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bit gate;
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constraint c {
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if (gate == 1'b1) {
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foreach (a[i]) {
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a[i] dist {
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4'd0 := 1,
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4'd9 := 1
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};
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}
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}
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}
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endclass
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// if (gate) foreach (q[i]) q[i] dist {...}, over a queue
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class ClsQueue;
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rand bit [2:0] q[$];
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bit gate;
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constraint sz {q.size() == 4;}
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constraint c {
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if (gate == 1'b1) {
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foreach (q[i]) {
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q[i] dist {
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[3'd0 : 3'd1] :/ 90,
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[3'd2 : 3'd5] :/ 10
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};
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}
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}
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}
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endclass
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// if (gate) foreach (d[i]) d[i] dist {...}, over a dynamic array
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class ClsDynArray;
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rand bit [2:0] d[];
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bit gate;
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constraint sz {d.size() == 4;}
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constraint c {
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if (gate == 1'b1) {
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foreach (d[i]) {
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d[i] dist {
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[3'd0 : 3'd1] :/ 90,
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[3'd2 : 3'd5] :/ 10
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};
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}
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}
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}
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endclass
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// Weight given by a variable rather than a literal
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class ClsVarWeight;
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rand bit [2:0] a[4];
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bit gate;
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int w;
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constraint c {
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if (gate == 1'b1) {
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foreach (a[i]) {
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a[i] dist {
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[3'd0 : 3'd1] :/ w,
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[3'd2 : 3'd5] :/ 1
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};
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}
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}
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}
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endclass
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// foreach (m[i]) if (gate) foreach (m[i][j]) m[i][j] dist {...}, so the
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// constraint if sits between the two foreach levels
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class ClsForeachIfForeach;
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rand bit [2:0] m[2][4];
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bit gate;
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constraint c {
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foreach (m[i]) {
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if (gate == 1'b1) {
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foreach (m[i][j]) {
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m[i][j] dist {
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[3'd0 : 3'd1] :/ 90,
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[3'd2 : 3'd5] :/ 10
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};
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}
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}
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}
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}
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endclass
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// if (gate) foreach (a[i]) if (gate2) a[i] dist {...}
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class ClsIfForeachIf;
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rand bit [2:0] a[4];
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bit gate, gate2;
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constraint c {
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if (gate == 1'b1) {
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foreach (a[i]) {
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if (gate2 == 1'b1) {
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a[i] dist {
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[3'd0 : 3'd1] :/ 90,
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[3'd2 : 3'd5] :/ 10
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};
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}
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}
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}
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}
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endclass
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module t;
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initial begin
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// dist inside if + foreach stays in range and reaches both buckets
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begin
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static ClsIf obj = new();
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int seen_zero, seen_nonzero;
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obj.gate = 1'b1;
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seen_zero = 0;
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seen_nonzero = 0;
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repeat (100) begin
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`checkd(obj.randomize(), 1);
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foreach (obj.a[i]) begin
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`checkd((obj.a[i] inside {[4'd0 : 4'd4]}), 1'b1);
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if (obj.a[i] == 0) seen_zero++;
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else seen_nonzero++;
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end
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end
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`checkgt(seen_zero, 0);
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`checkgt(seen_nonzero, 0);
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end
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// Each arm of an if/else selects its own distribution
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begin
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static ClsIfElse obj = new();
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int seen_zero, seen_nonzero, seen_else;
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obj.gate = 1'b1;
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seen_zero = 0;
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seen_nonzero = 0;
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repeat (100) begin
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`checkd(obj.randomize(), 1);
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foreach (obj.a[i]) begin
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`checkd((obj.a[i] inside {[4'd0 : 4'd4]}), 1'b1);
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if (obj.a[i] == 0) seen_zero++;
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else seen_nonzero++;
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end
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end
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`checkgt(seen_zero, 0);
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`checkgt(seen_nonzero, 0);
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obj.gate = 1'b0;
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seen_else = 0;
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repeat (100) begin
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`checkd(obj.randomize(), 1);
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foreach (obj.a[i]) begin
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`checkd((obj.a[i] inside {[4'd8 : 4'd11]}), 1'b1);
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seen_else++;
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end
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end
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`checkd(seen_else, 400);
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end
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// dist under an implication nested inside the if + foreach
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begin
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static ClsIfImpl obj = new();
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int seen_zero, seen_nonzero;
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obj.gate = 1'b1;
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obj.gate2 = 1'b1;
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seen_zero = 0;
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seen_nonzero = 0;
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repeat (100) begin
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`checkd(obj.randomize(), 1);
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foreach (obj.a[i]) begin
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`checkd((obj.a[i] inside {[4'd0 : 4'd4]}), 1'b1);
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if (obj.a[i] == 0) seen_zero++;
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else seen_nonzero++;
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end
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end
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`checkgt(seen_zero, 0);
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`checkgt(seen_nonzero, 0);
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end
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// A rand if condition applies the dist to every element when taken, and the
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// 90 :/ 10 weights make the low bucket dominate
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begin
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static ClsRandSel obj = new();
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int seen_low, seen_high;
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seen_low = 0;
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seen_high = 0;
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repeat (100) begin
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`checkd(obj.randomize() with {sel == 1'b1;}, 1);
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`checkd(obj.sel, 1'b1);
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foreach (obj.a[i]) begin
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`checkd((obj.a[i] inside {[3'd0 : 3'd5]}), 1'b1);
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if (obj.a[i] <= 1) seen_low++;
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else seen_high++;
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end
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end
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`checkgt(seen_low, 0);
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`checkgt(seen_high, 0);
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`checkgt(seen_low, seen_high);
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end
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// Two dist constraints in one foreach body are both honored
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begin
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static ClsMulti obj = new();
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int seen_low, seen_high;
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obj.gate = 1'b1;
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seen_low = 0;
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seen_high = 0;
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repeat (100) begin
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`checkd(obj.randomize(), 1);
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foreach (obj.a[i]) begin
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`checkd((obj.a[i] inside {[3'd0 : 3'd5]}), 1'b1);
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`checkd(obj.b[i], 3'd7);
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if (obj.a[i] <= 1) seen_low++;
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else seen_high++;
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end
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end
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`checkgt(seen_low, 0);
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`checkgt(seen_high, 0);
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`checkgt(seen_low, seen_high);
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end
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// A dist in a nested foreach under a constraint if
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begin
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static ClsNested obj = new();
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int seen_low, seen_high;
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obj.gate = 1'b1;
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seen_low = 0;
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seen_high = 0;
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repeat (100) begin
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`checkd(obj.randomize(), 1);
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foreach (obj.m[i]) begin
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foreach (obj.m[i][j]) begin
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`checkd((obj.m[i][j] inside {[3'd0 : 3'd5]}), 1'b1);
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if (obj.m[i][j] <= 1) seen_low++;
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else seen_high++;
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end
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end
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end
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`checkgt(seen_low, 0);
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`checkgt(seen_high, 0);
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`checkgt(seen_low, seen_high);
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end
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// The bucket is drawn per element, so one randomize() call can place
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// different elements in different buckets
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begin
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static ClsIndep obj = new();
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int seen_mixed;
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obj.gate = 1'b1;
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seen_mixed = 0;
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repeat (100) begin
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int seen_lo, seen_hi;
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`checkd(obj.randomize(), 1);
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seen_lo = 0;
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seen_hi = 0;
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foreach (obj.a[i]) begin
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`checkd((obj.a[i] inside {4'd0, 4'd9}), 1'b1);
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if (obj.a[i] == 4'd0) seen_lo++;
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else seen_hi++;
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end
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if (seen_lo > 0 && seen_hi > 0) seen_mixed++;
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end
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`checkgt(seen_mixed, 0);
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end
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// dist applies to every element of a queue
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begin
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static ClsQueue obj = new();
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int seen_low, seen_high;
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obj.gate = 1'b1;
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seen_low = 0;
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seen_high = 0;
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repeat (100) begin
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`checkd(obj.randomize(), 1);
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`checkd(obj.q.size(), 4);
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foreach (obj.q[i]) begin
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`checkd((obj.q[i] inside {[3'd0 : 3'd5]}), 1'b1);
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if (obj.q[i] <= 1) seen_low++;
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else seen_high++;
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end
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end
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`checkgt(seen_low, 0);
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`checkgt(seen_high, 0);
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`checkgt(seen_low, seen_high);
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end
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// dist applies to every element of a dynamic array
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begin
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static ClsDynArray obj = new();
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int seen_low, seen_high;
|
||||
obj.gate = 1'b1;
|
||||
seen_low = 0;
|
||||
seen_high = 0;
|
||||
repeat (100) begin
|
||||
`checkd(obj.randomize(), 1);
|
||||
`checkd(obj.d.size(), 4);
|
||||
foreach (obj.d[i]) begin
|
||||
`checkd((obj.d[i] inside {[3'd0 : 3'd5]}), 1'b1);
|
||||
if (obj.d[i] <= 1) seen_low++;
|
||||
else seen_high++;
|
||||
end
|
||||
end
|
||||
`checkgt(seen_low, 0);
|
||||
`checkgt(seen_high, 0);
|
||||
`checkgt(seen_low, seen_high);
|
||||
end
|
||||
|
||||
// A weight held in a variable is read at run time, so a 3 :/ 1 split
|
||||
// reaches both buckets and leaves the low one dominant
|
||||
begin
|
||||
static ClsVarWeight obj = new();
|
||||
int seen_low, seen_high;
|
||||
obj.gate = 1'b1;
|
||||
obj.w = 3;
|
||||
seen_low = 0;
|
||||
seen_high = 0;
|
||||
repeat (100) begin
|
||||
`checkd(obj.randomize(), 1);
|
||||
foreach (obj.a[i]) begin
|
||||
`checkd((obj.a[i] inside {[3'd0 : 3'd5]}), 1'b1);
|
||||
if (obj.a[i] <= 1) seen_low++;
|
||||
else seen_high++;
|
||||
end
|
||||
end
|
||||
`checkgt(seen_low, 0);
|
||||
`checkgt(seen_high, 0);
|
||||
`checkgt(seen_low, seen_high);
|
||||
end
|
||||
|
||||
// A constraint if between two foreach levels
|
||||
begin
|
||||
static ClsForeachIfForeach obj = new();
|
||||
int seen_low, seen_high;
|
||||
obj.gate = 1'b1;
|
||||
seen_low = 0;
|
||||
seen_high = 0;
|
||||
repeat (100) begin
|
||||
`checkd(obj.randomize(), 1);
|
||||
foreach (obj.m[i]) begin
|
||||
foreach (obj.m[i][j]) begin
|
||||
`checkd((obj.m[i][j] inside {[3'd0 : 3'd5]}), 1'b1);
|
||||
if (obj.m[i][j] <= 1) seen_low++;
|
||||
else seen_high++;
|
||||
end
|
||||
end
|
||||
end
|
||||
`checkgt(seen_low, 0);
|
||||
`checkgt(seen_high, 0);
|
||||
`checkgt(seen_low, seen_high);
|
||||
end
|
||||
|
||||
// A second constraint if inside the foreach body
|
||||
begin
|
||||
static ClsIfForeachIf obj = new();
|
||||
int seen_low, seen_high;
|
||||
obj.gate = 1'b1;
|
||||
obj.gate2 = 1'b1;
|
||||
seen_low = 0;
|
||||
seen_high = 0;
|
||||
repeat (100) begin
|
||||
`checkd(obj.randomize(), 1);
|
||||
foreach (obj.a[i]) begin
|
||||
`checkd((obj.a[i] inside {[3'd0 : 3'd5]}), 1'b1);
|
||||
if (obj.a[i] <= 1) seen_low++;
|
||||
else seen_high++;
|
||||
end
|
||||
end
|
||||
`checkgt(seen_low, 0);
|
||||
`checkgt(seen_high, 0);
|
||||
`checkgt(seen_low, seen_high);
|
||||
end
|
||||
|
||||
$write("*-* All Finished *-*\n");
|
||||
$finish;
|
||||
end
|
||||
endmodule
|
||||
Loading…
Reference in New Issue