yosys/tests/silimate/sub2neg.ys

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log -header "Simple positive case"
log -push
design -reset
read_verilog <<EOF
module top(a, b, y);
input wire signed [7:0] a;
input wire signed [7:0] b;
output wire signed [7:0] y;
assign y = a - b;
endmodule
EOF
proc; opt
check -assert
equiv_opt -assert negopt -pre
design -load postopt
select -assert-count 1 t:$add
select -assert-count 1 t:$neg
select -assert-none t:$sub
design -reset
log -pop
log -header "Unsigned positive case"
log -push
design -reset
read_verilog <<EOF
module top(a, b, y);
input wire [7:0] a;
input wire [7:0] b;
output wire [7:0] y;
assign y = a - b;
endmodule
EOF
proc; opt
check -assert
equiv_opt -assert negopt -pre
design -load postopt
select -assert-count 1 t:$add
select -assert-count 1 t:$neg
select -assert-none t:$sub
design -reset
log -pop
log -header "Negative case: constant subtrahend"
log -push
design -reset
read_verilog <<EOF
module top(a, y);
input wire signed [7:0] a;
output wire signed [7:0] y;
assign y = a - 8'd5;
endmodule
EOF
proc; opt
check -assert
equiv_opt -assert negopt -pre
design -load postopt
# Should NOT transform because constant subtraction is kept as $sub
select -assert-count 1 t:$sub
select -assert-none t:$add
select -assert-none t:$neg
design -reset
log -pop
log -header "Anchor case: output wider than inputs"
log -push
design -reset
read_verilog <<EOF
module top(a, b, y);
input wire signed [7:0] a;
input wire signed [7:0] b;
output wire signed [11:0] y;
assign y = a - b;
endmodule
EOF
proc; opt
check -assert
equiv_opt -assert negopt -pre
design -load postopt
select -assert-count 1 t:$add
select -assert-count 1 t:$neg
select -assert-none t:$sub
design -reset
log -pop
log -header "Signedness case"
log -push
design -reset
read_verilog <<EOF
module top(a, b, y);
input wire signed [7:0] a;
input wire [7:0] b;
output wire signed [7:0] y;
assign y = a - b;
endmodule
EOF
proc; opt
check -assert
equiv_opt -assert negopt -pre
design -load postopt
select -assert-count 1 t:$add
select -assert-count 1 t:$neg
select -assert-none t:$sub
design -reset
log -pop