diff options
| -rw-r--r-- | passes/opt/opt_expr.cc | 2 | ||||
| -rw-r--r-- | tests/opt/opt_expr.ys | 14 |
2 files changed, 15 insertions, 1 deletions
diff --git a/passes/opt/opt_expr.cc b/passes/opt/opt_expr.cc index c4da613ab..73f48317a 100644 --- a/passes/opt/opt_expr.cc +++ b/passes/opt/opt_expr.cc @@ -748,7 +748,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons if (cell->type.in(ID($shiftx), ID($shift))) { SigSpec sig_a = assign_map(cell->getPort(ID::A)); int width; - bool trim_x = true; + bool trim_x = cell->type == ID($shiftx) || !keepdc; bool trim_0 = cell->type == ID($shift); for (width = GetSize(sig_a); width > 1; width--) { if ((trim_x && sig_a[width-1] == State::Sx) || diff --git a/tests/opt/opt_expr.ys b/tests/opt/opt_expr.ys index 02be20a62..ecc2c8da8 100644 --- a/tests/opt/opt_expr.ys +++ b/tests/opt/opt_expr.ys @@ -277,3 +277,17 @@ check equiv_opt opt_expr design -load postopt select -assert-count 1 t:$shift r:A_WIDTH=10 %i + +########### + +design -reset +read_verilog -icells <<EOT +module opt_expr_shift_3bit_keepdc(input [9:0] a, input [3:0] b, output [2:0] y); + \$shift #(.A_SIGNED(0), .B_SIGNED(0), .A_WIDTH(14), .B_WIDTH(4), .Y_WIDTH(3)) shift (.A({4'b0x0x,a}), .B(b), .Y(y)); +endmodule +EOT +check + +equiv_opt opt_expr -keepdc +design -load postopt +select -assert-count 1 t:$shift r:A_WIDTH=13 %i |