verilog: fix dynamic dynamic range asgn elab

tests/verilog/dynamic_range_lhs.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+run() {
+    alt=$1
+    span=$2
+    left=$3
+    right=$4
+    echo "a=$alt s=$span l=$left r=$right"
+
+    ../../yosys -q \
+        -DALT=$alt \
+        -DSPAN=$span \
+        -DLEFT=$left \
+        -DRIGHT=$right \
+        -p "read_verilog dynamic_range_lhs.v" \
+        -p "proc" \
+        -p "equiv_make gold gate equiv" \
+        -p "equiv_simple" \
+        -p "equiv_status -assert"
+}
+
+trap 'echo "ERROR in dynamic_range_lhs.sh span=$span left=$left right=$right" >&2; exit 1' ERR
+
+for alt in `seq 0 1`; do
+for span in `seq 1 4`; do
+for left in `seq -4 4`; do
+for right in `seq $(expr $left + -3) $(expr $left + 3)`; do
+    run $alt $span $left $right
+done
+done
+done
+done

tests/verilog/dynamic_range_lhs.v

@@ -0,0 +1,76 @@
+module gate(
+    output reg [`LEFT:`RIGHT] out_u, out_s,
+    (* nowrshmsk = `ALT *)
+    input wire data,
+    input wire [1:0] sel1, sel2
+);
+always @* begin
+    out_u = 0;
+    out_s = 0;
+    case (`SPAN)
+    1: begin
+        out_u[sel1*sel2] = data;
+        out_s[$signed(sel1*sel2)] = data;
+    end
+    2: begin
+        out_u[sel1*sel2+:2] = {data, data};
+        out_s[$signed(sel1*sel2)+:2] = {data, data};
+    end
+    3: begin
+        out_u[sel1*sel2+:3] = {data, data, data};
+        out_s[$signed(sel1*sel2)+:3] = {data, data, data};
+    end
+    4: begin
+        out_u[sel1*sel2+:4] = {data, data, data, data};
+        out_s[$signed(sel1*sel2)+:4] = {data, data, data, data};
+    end
+    endcase
+end
+endmodule
+
+module gold(
+    output reg [`LEFT:`RIGHT] out_u, out_s,
+    input wire data,
+    input wire [1:0] sel1, sel2
+);
+task set;
+    input integer a, b;
+    localparam LOW = `LEFT > `RIGHT ? `RIGHT : `LEFT;
+    localparam HIGH = `LEFT > `RIGHT ? `LEFT : `RIGHT;
+    if (LOW <= a && a <= HIGH)
+        out_u[a] = data;
+    if (LOW <= b && b <= HIGH)
+        out_s[b] = data;
+endtask
+always @* begin
+    out_u = 0;
+    out_s = 0;
+    case (sel1*sel2)
+        2'b00: set(0, 0);
+        2'b01: set(1, 1);
+        2'b10: set(2, -2);
+        2'b11: set(3, -1);
+    endcase
+    if (`SPAN >= 2)
+        case (sel1*sel2)
+            2'b00: set(1, 1);
+            2'b01: set(2, 2);
+            2'b10: set(3, -1);
+            2'b11: set(4, 0);
+        endcase
+    if (`SPAN >= 3)
+        case (sel1*sel2)
+            2'b00: set(2, 2);
+            2'b01: set(3, 3);
+            2'b10: set(4, 0);
+            2'b11: set(5, 1);
+        endcase
+    if (`SPAN >= 4)
+        case (sel1*sel2)
+            2'b00: set(3, 3);
+            2'b01: set(4, 4);
+            2'b10: set(5, 1);
+            2'b11: set(6, 2);
+        endcase
+end
+endmodule