opt_share: Refactor, fix some bugs.

Fixes #2334.
Fixes #2335.
Fixes #2336.

3 files changed, 54 insertions, 0 deletions

diff --git a/tests/opt/opt_share_bug2334.ys b/tests/opt/opt_share_bug2334.ys
new file mode 100644
index 000000000..004d98349
--- /dev/null
+++ b/tests/opt/opt_share_bug2334.ys
@@ -0,0 +1,13 @@
+read_verilog <<EOT
+
+module t(input [3:0] A, input [3:0] B, input [3:0] C, input S, output [3:0] Y);
+
+wire [3:0] t = A + C;
+
+assign Y = S ? A + B : {4{t[0]}};
+
+endmodule
+
+EOT
+
+equiv_opt -assert opt_share
diff --git a/tests/opt/opt_share_bug2335.ys b/tests/opt/opt_share_bug2335.ys
new file mode 100644
index 000000000..0846a9ec3
--- /dev/null
+++ b/tests/opt/opt_share_bug2335.ys
@@ -0,0 +1,27 @@
+read_verilog <<EOT
+
+module top(...);
+
+input [3:0] A, B, C;
+input S;
+input [1:0] T;
+output [3:0] X;
+output reg [3:0] Y;
+
+wire [3:0] D = A + B;
+
+assign X = S ? D : A + C;
+always @* begin
+        case(T)
+        2'b01: Y <= A;
+        2'b10: Y <= B;
+        default: Y <= D;
+        endcase
+end
+
+endmodule
+
+EOT
+
+proc
+equiv_opt -assert opt_share
diff --git a/tests/opt/opt_share_bug2336.ys b/tests/opt/opt_share_bug2336.ys
new file mode 100644
index 000000000..cd472ef46
--- /dev/null
+++ b/tests/opt/opt_share_bug2336.ys
@@ -0,0 +1,14 @@
+read_verilog <<EOT
+
+module top(input [3:0] A, B, C, input S, output [2:0] O);
+
+wire [3:0] tb = A + B;
+wire [3:0] tc = A + C;
+
+assign O = S ? tb[3:1] : tc[3:1];
+
+endmodule
+
+EOT
+
+equiv_opt -assert opt_share