Fix wide conditional short circuiting (#7155).

Fixes #7155.

Changes

@@ -13,6 +13,7 @@ Verilator 5.047 devel
 
 **Other:**
 
+* Fix wide conditional short circuiting (#7155).
 
 
 Verilator 5.046 2026-02-28

include/verilated_funcs.h

@@ -2792,10 +2792,9 @@ static inline void VL_SELASSIGN_WW(int rbits, int obits, WDataOutP iowp, WDataIn
 //======================================================================
 // Triops
 
-static inline WDataOutP VL_COND_WIWW(int obits, WDataOutP owp, int cond, WDataInP const w1p,
-                                     WDataInP const w2p) VL_MT_SAFE {
-    return VL_MEMCPY_W(owp, cond ? w1p : w2p, VL_WORDS_I(obits));
-}
+// This must be a macro in order for short-circuiting of the values to work.
+#define VL_COND_WIWW(obits, owp, cond, w1p, w2p) \
+    VL_MEMCPY_W(owp, (cond) ? (w1p) : (w2p), VL_WORDS_I(obits))
 
 //======================================================================
 // Constification

test_regress/t/t_cover_line_wide_ternary.out

@@ -39,37 +39,37 @@
 -000009  point: type=line comment=block hier=top.t
 %000009         {intf_sel_ff.foo, intf_sel_ff.bar, intf_sel_ff.baz} <=
 -000009  point: type=line comment=block hier=top.t
-%000009             cyc[0] ?
--000009  point: type=branch comment=cond_then hier=top.t
-%000009             {intfs[1].foo, intfs[1].bar, intfs[1].baz} :
--000009  point: type=branch comment=cond_then hier=top.t
--000009  point: type=branch comment=cond_else hier=top.t
-%000009             {intfs[0].foo, intfs[0].bar, intfs[0].baz};
--000009  point: type=branch comment=cond_else hier=top.t
+%000005             cyc[0] ?
+-000005  point: type=branch comment=cond_then hier=top.t
+%000005             {intfs[1].foo, intfs[1].bar, intfs[1].baz} :
+-000005  point: type=branch comment=cond_then hier=top.t
+-000004  point: type=branch comment=cond_else hier=top.t
+%000004             {intfs[0].foo, intfs[0].bar, intfs[0].baz};
+-000004  point: type=branch comment=cond_else hier=top.t
             end
         
  000010     always_comb begin
 +000010  point: type=line comment=block hier=top.t
  000010         {intf_sel_comb.foo, intf_sel_comb.bar, intf_sel_comb.baz} =
 +000010  point: type=line comment=block hier=top.t
- 000010             cyc[0] ?
-+000010  point: type=branch comment=cond_then hier=top.t
- 000010             {intfs[1].foo, intfs[1].bar, intfs[1].baz} :
-+000010  point: type=branch comment=cond_then hier=top.t
-+000010  point: type=branch comment=cond_else hier=top.t
- 000010             {intfs[0].foo, intfs[0].bar, intfs[0].baz};
-+000010  point: type=branch comment=cond_else hier=top.t
+%000005             cyc[0] ?
+-000005  point: type=branch comment=cond_then hier=top.t
+%000005             {intfs[1].foo, intfs[1].bar, intfs[1].baz} :
+-000005  point: type=branch comment=cond_then hier=top.t
+-000005  point: type=branch comment=cond_else hier=top.t
+%000005             {intfs[0].foo, intfs[0].bar, intfs[0].baz};
+-000005  point: type=branch comment=cond_else hier=top.t
             end
         
             assign
                 {intf_sel_assign.foo, intf_sel_assign.bar, intf_sel_assign.baz} =
- 000010             cyc[0] ?
-+000010  point: type=branch comment=cond_then hier=top.t
- 000010             {intfs[1].foo, intfs[1].bar, intfs[1].baz} :
-+000010  point: type=branch comment=cond_then hier=top.t
-+000010  point: type=branch comment=cond_else hier=top.t
- 000010             {intfs[0].foo, intfs[0].bar, intfs[0].baz};
-+000010  point: type=branch comment=cond_else hier=top.t
+%000005             cyc[0] ?
+-000005  point: type=branch comment=cond_then hier=top.t
+%000005             {intfs[1].foo, intfs[1].bar, intfs[1].baz} :
+-000005  point: type=branch comment=cond_then hier=top.t
+-000005  point: type=branch comment=cond_else hier=top.t
+%000005             {intfs[0].foo, intfs[0].bar, intfs[0].baz};
+-000005  point: type=branch comment=cond_else hier=top.t
         
 %000009     always @ (posedge clk) begin
 -000009  point: type=line comment=block hier=top.t

test_regress/t/t_math_cond_short_circuit.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# 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.
+# SPDX-FileCopyrightText: 2026 Wilson Snyder
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+import vltest_bootstrap
+
+test.scenarios('simulator')
+
+test.compile()
+
+test.execute()
+
+test.passes()

test_regress/t/t_math_cond_short_circuit.v

@@ -0,0 +1,91 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
+// SPDX-License-Identifier: CC0-1.0
+
+// verilog_format: off
+`define stop $stop
+`define checkh(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d:  got=%0x exp=%0x (%s !== %s)\n", `__FILE__,`__LINE__, (gotv), (expv), `"gotv`", `"expv`"); `stop; end while(0);
+`ifdef verilator
+ `define optimize_barrier $c("")
+`else
+ `define optimize_barrier
+`endif
+// verilog_format: on
+
+module t;
+
+  class Map;
+    virtual function bit [95:0] get_value();
+      bit [95:0] result = 96'h11111111_22222222_33333333;
+      `optimize_barrier;
+      return result;
+    endfunction
+  endclass
+
+  class Cls;
+    function bit [95:0] get_default();
+      bit [95:0] result = 96'haaaaaaaa_bbbbbbbb_cccccccc;
+      `optimize_barrier;
+      return result;
+    endfunction
+
+    function bit [95:0] compute_LL(Map map);
+      bit [95:0] result;
+      `optimize_barrier;
+      // Wide operation is required, as results in VL_COND call which evaluates
+      // arguments
+      result = map == null ? this.get_default() : map.get_value();
+      `optimize_barrier;
+      return result;
+    endfunction
+
+    function bit [95:0] compute_LC(Map map);
+      bit [95:0] result;
+      bit sel1 = map == null;
+      `optimize_barrier;
+      result = sel1 ? 96'hffffffff_ffffffff_ffffffff : map.get_value();
+      `optimize_barrier;
+      return result;
+    endfunction
+
+    function bit [95:0] compute_CL(Map map);
+      bit [95:0] result;
+      bit sel1 = map != null;
+      `optimize_barrier;
+      result = sel1 ? map.get_value() : 96'hffffffff_ffffffff_ffffffff;
+      `optimize_barrier;
+      return result;
+    endfunction
+
+  endclass
+
+  initial begin
+    Cls c;
+    Map mnull;
+    Map m;
+    bit [95:0] res;
+
+    c = new;
+    m = new;
+
+    res = c.compute_LL(mnull);
+    `checkh(res, 96'haaaaaaaa_bbbbbbbb_cccccccc);
+    res = c.compute_LL(m);
+    `checkh(res, 96'h11111111_22222222_33333333);
+
+    res = c.compute_LC(mnull);
+    `checkh(res, 96'hffffffff_ffffffff_ffffffff);
+    res = c.compute_LC(m);
+    `checkh(res, 96'h11111111_22222222_33333333);
+
+    res = c.compute_CL(mnull);
+    `checkh(res, 96'hffffffff_ffffffff_ffffffff);
+    res = c.compute_CL(m);
+    `checkh(res, 96'h11111111_22222222_33333333);
+
+    $finish;
+  end
+
+endmodule