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Really get rid of 'opt_expr -fine' by being explicit

This commit is contained in:
Eddie Hung 2019-09-10 14:26:12 -07:00
parent c460d10e60
commit 76eedee089
2 changed files with 33 additions and 9 deletions
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39
techlibs/common/mul2dsp.v
View File

@ -148,8 +148,17 @@ module _80_mul (A, B, Y);
// reduction' approach also exists...
if (i == 0)
assign partial_sum[i] = partial[i];
else
assign partial_sum[i] = (partial[i] << i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)) + partial_sum[i-1];
else begin
// Rewrite the following statement explicitly in order
// to save on a call to 'opt_expr -fine' which would
// optimise away the '<<' op and trim size of adder
//assign partial_sum[i] = (partial[i] << i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)) + partial_sum[i-1];
wire [Y_WIDTH-1:0] shifted_sum = {partial[i], {i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom){1'b0}}};
assign partial_sum[i] = {
partial_sum[i-1][i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)-1:0],
shifted_sum[Y_WIDTH-1:i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)] + partial_sum[i-1][Y_WIDTH-1:i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)]
};
end
end
\$__mul #(
@ -163,7 +172,12 @@ module _80_mul (A, B, Y);
.B(B),
.Y(last_partial)
);
assign partial_sum[n] = (last_partial << n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)) + partial_sum[n-1];
//assign partial_sum[n] = (last_partial << n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)) + partial_sum[n-1];
wire [Y_WIDTH-1:0] shifted_sum = {last_partial, {n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom){1'b0}}};
assign partial_sum[n] = {
partial_sum[n-1][n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)-1:0],
shifted_sum[Y_WIDTH-1:n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)] + partial_sum[n-1][Y_WIDTH-1:n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)]
};
assign Y = partial_sum[n];
end
else if (B_WIDTH > `DSP_B_MAXWIDTH) begin
@ -199,8 +213,16 @@ module _80_mul (A, B, Y);
// reduction' approach also exists...
if (i == 0)
assign partial_sum[i] = partial[i];
else
assign partial_sum[i] = (partial[i] << i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)) + partial_sum[i-1];
else begin
// Rewrite the following statement explicitly in order
// to save on a call to 'opt_expr -fine' which would
// optimise away the '<<' op and trim size of adder
wire [Y_WIDTH-1:0] shifted_sum = {partial[i], {i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom){1'b0}}};
assign partial_sum[i] = {
partial_sum[i-1][i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)-1:0],
shifted_sum[Y_WIDTH-1:i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)] + partial_sum[i-1][Y_WIDTH-1:i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)]
};
end
end
\$__mul #(
@ -214,7 +236,12 @@ module _80_mul (A, B, Y);
.B(B[B_WIDTH-1 -: last_B_WIDTH]),
.Y(last_partial)
);
assign partial_sum[n] = (last_partial << n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)) + partial_sum[n-1];
//assign partial_sum[n] = (last_partial << n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)) + partial_sum[n-1];
wire [Y_WIDTH-1:0] shifted_sum = {last_partial, {n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom){1'b0}}};
assign partial_sum[n] = {
partial_sum[n-1][n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)-1:0],
shifted_sum[Y_WIDTH-1:n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)] + partial_sum[n-1][Y_WIDTH-1:n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)]
};
assign Y = partial_sum[n];
end
else begin

3
techlibs/xilinx/synth_xilinx.cc
View File

@ -325,9 +325,6 @@ struct SynthXilinxPass : public ScriptPass
if (!nodsp || help_mode) {
// NB: Xilinx multipliers are signed only
run("techmap -map +/mul2dsp.v -map +/xilinx/dsp_map.v -D DSP_A_MAXWIDTH=25 -D DSP_A_MAXWIDTH_PARTIAL=18 -D DSP_B_MAXWIDTH=18 -D DSP_SIGNEDONLY=1 -D DSP_NAME=$__MUL25X18", "(skip if '-nodsp')");
// Necessary for optimising away $shl cells, as well as $add cells
// that have inputs with 1'b0 LSBs
run("opt_expr -fine", " (skip if '-nodsp')");
run("xilinx_dsp", " (skip if '-nodsp')");
run("chtype -set $mul t:$__soft_mul"," (skip if '-nodsp')");
}