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| author | Eddie Hung <eddie@fpgeh.com> | 2019-09-26 09:57:11 -0700 |
|---|---|---|
| committer | Eddie Hung <eddie@fpgeh.com> | 2019-09-26 09:57:11 -0700 |
| commit | 27e5bf5aad229ef330bfea932f6b194ec5c09b68 (patch) | |
| tree | 1cc494f9b2e75298da55df2303c8f833a20ff86f /techlibs/common/mul2dsp.v | |
| parent | 35aaa8d73a75f36a42eea9ef2b210d9e79e5edc3 (diff) | |
| download | yosys-27e5bf5aad229ef330bfea932f6b194ec5c09b68.tar.gz yosys-27e5bf5aad229ef330bfea932f6b194ec5c09b68.tar.bz2 yosys-27e5bf5aad229ef330bfea932f6b194ec5c09b68.zip | |
Stop trying to be too smart by prematurely optimising
Diffstat (limited to 'techlibs/common/mul2dsp.v')
| -rw-r--r-- | techlibs/common/mul2dsp.v | 40 |
1 files changed, 6 insertions, 34 deletions
diff --git a/techlibs/common/mul2dsp.v b/techlibs/common/mul2dsp.v index 60b180ac0..6dcdcf226 100644 --- a/techlibs/common/mul2dsp.v +++ b/techlibs/common/mul2dsp.v @@ -146,17 +146,8 @@ module _80_mul (A, B, Y); // reduction' approach also exists...
if (i == 0)
assign partial_sum[i] = partial[i];
- 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];
- if (A_SIGNED && B_SIGNED)
- assign partial_sum[i][Y_WIDTH-1:i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)] = partial[i] + $signed(partial_sum[i-1][Y_WIDTH-1:i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)]);
- else
- assign partial_sum[i][Y_WIDTH-1:i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)] = partial[i] + partial_sum[i-1][Y_WIDTH-1:i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)];
- assign partial_sum[i][i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)-1:0] = partial_sum[i-1][i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)-1:0];
- end
+ else
+ assign partial_sum[i] = (partial[i] << (* mul2dsp *) i*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)) + (* mul2dsp *) partial_sum[i-1];
end
\$__mul #(
@@ -170,12 +161,7 @@ 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];
- if (A_SIGNED && B_SIGNED)
- assign partial_sum[n][Y_WIDTH-1:n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)] = last_partial + $signed(partial_sum[n-1][Y_WIDTH-1:n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)]);
- else
- assign partial_sum[n][Y_WIDTH-1:n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)] = last_partial + partial_sum[n-1][Y_WIDTH-1:n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)];
- assign partial_sum[n][n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)-1:0] = partial_sum[n-1][n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)-1:0];
+ assign partial_sum[n] = (last_partial << (* mul2dsp *) n*(`DSP_A_MAXWIDTH_PARTIAL-sign_headroom)) + (* mul2dsp *) partial_sum[n-1];
assign Y = partial_sum[n];
end
else if (B_WIDTH > `DSP_B_MAXWIDTH) begin
@@ -211,17 +197,8 @@ module _80_mul (A, B, Y); // reduction' approach also exists...
if (i == 0)
assign partial_sum[i] = partial[i];
- 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_B_MAXWIDTH_PARTIAL-sign_headroom)) + partial_sum[i-1];
- if (A_SIGNED && B_SIGNED)
- assign partial_sum[i][Y_WIDTH-1:i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)] = partial[i] + $signed(partial_sum[i-1][Y_WIDTH-1:i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)]);
- else
- assign partial_sum[i][Y_WIDTH-1:i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)] = partial[i] + partial_sum[i-1][Y_WIDTH-1:i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)];
- assign partial_sum[i][i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)-1:0] = partial_sum[i-1][i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)-1:0];
- end
+ else
+ assign partial_sum[i] = (partial[i] << i*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)) + partial_sum[i-1];
end
\$__mul #(
@@ -235,12 +212,7 @@ 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];
- if (A_SIGNED && B_SIGNED)
- assign partial_sum[n][Y_WIDTH-1:n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)] = last_partial + $signed(partial_sum[n-1][Y_WIDTH-1:n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)]);
- else
- assign partial_sum[n][Y_WIDTH-1:n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)] = last_partial + partial_sum[n-1][Y_WIDTH-1:n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)];
- assign partial_sum[n][n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)-1:0] = partial_sum[n-1][n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)-1:0];
+ assign partial_sum[n] = (last_partial << n*(`DSP_B_MAXWIDTH_PARTIAL-sign_headroom)) + partial_sum[n-1];
assign Y = partial_sum[n];
end
else begin
|