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simplemap: Moves $pmux mapping from techmap.v to simple map

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This Fixes the slow downs I observed in techmap.v, which we
attempted to fix via the simplify ast.h route originally. This
turned out to be rather complex though.

By moving $pmux to simplemap we can just avoid that code. My
test case now runs in 310s which is 40s faster than the baseline
change.

B:507898959
Signed-off-by: Ethan Mahintorabi <ethanmoon@google.com>
This commit is contained in:
Ethan Mahintorabi 2026-04-29 20:48:14 +00:00
parent 92287d4857
commit 805c302411
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2 changed files with 45 additions and 44 deletions
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44
techlibs/common/techmap.v
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@ -59,7 +59,7 @@ module _90_simplemap_compare_ops;
endmodule
(* techmap_simplemap *)
(* techmap_celltype = "$buf $pos $slice $concat $mux $tribuf $bmux $bwmux $bweqx" *)
(* techmap_celltype = "$buf $pos $slice $concat $mux $pmux $tribuf $bmux $bwmux $bweqx" *)
module _90_simplemap_various;
endmodule
@ -563,48 +563,6 @@ module _90_pow (A, B, Y);
wire _TECHMAP_FAIL_ = 1;
endmodule
// --------------------------------------------------------
// Parallel Multiplexers
// --------------------------------------------------------
(* techmap_celltype = "$pmux" *)
module _90_pmux (A, B, S, Y);
parameter WIDTH = 1;
parameter S_WIDTH = 1;
(* force_downto *)
input [WIDTH-1:0] A;
(* force_downto *)
input [WIDTH*S_WIDTH-1:0] B;
(* force_downto *)
input [S_WIDTH-1:0] S;
(* force_downto *)
output [WIDTH-1:0] Y;
(* force_downto *)
wire [WIDTH-1:0] Y_B;
genvar i, j;
generate
(* force_downto *)
wire [WIDTH*S_WIDTH-1:0] B_AND_S;
for (i = 0; i < S_WIDTH; i = i + 1) begin:B_AND
assign B_AND_S[WIDTH*(i+1)-1:WIDTH*i] = B[WIDTH*(i+1)-1:WIDTH*i] & {WIDTH{S[i]}};
end:B_AND
for (i = 0; i < WIDTH; i = i + 1) begin:B_OR
(* force_downto *)
wire [S_WIDTH-1:0] B_AND_BITS;
for (j = 0; j < S_WIDTH; j = j + 1) begin:B_AND_BITS_COLLECT
assign B_AND_BITS[j] = B_AND_S[WIDTH*j+i];
end:B_AND_BITS_COLLECT
assign Y_B[i] = |B_AND_BITS;
end:B_OR
endgenerate
assign Y = |S ? Y_B : A;
endmodule
// --------------------------------------------------------
// Demultiplexers
// --------------------------------------------------------