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Add force_downto and force_upto wire attributes.

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Fixes #2058.
This commit is contained in:
Marcelina Kościelnicka 2020-05-18 18:15:03 +02:00
parent 2d573a0ff6
commit aee439360b
43 changed files with 258 additions and 27 deletions
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12
techlibs/common/cmp2lcu.v
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@ -12,8 +12,11 @@ parameter A_WIDTH = 0;
parameter B_WIDTH = 0;
parameter Y_WIDTH = 0;
(* force_downto *)
input [A_WIDTH-1:0] A;
(* force_downto *)
input [B_WIDTH-1:0] B;
(* force_downto *)
output [Y_WIDTH-1:0] Y;
parameter _TECHMAP_CELLTYPE_ = "";
@ -32,7 +35,9 @@ generate
else begin
// Perform sign extension on A and B
localparam WIDTH = A_WIDTH > B_WIDTH ? A_WIDTH : B_WIDTH;
(* force_downto *)
wire [WIDTH-1:0] AA = {{(WIDTH-A_WIDTH){A_SIGNED ? A[A_WIDTH-1] : 1'b0}}, A};
(* force_downto *)
wire [WIDTH-1:0] BB = {{(WIDTH-B_WIDTH){B_SIGNED ? B[B_WIDTH-1] : 1'b0}}, B};
// For $ge operation, start with the assumption that A and B are
// equal (propagating this equality if A and B turn out to be so)
@ -54,9 +59,13 @@ parameter LCU_WIDTH = 1;
parameter BUDGET = 0;
parameter CI = 0;
(* force_downto *)
input [AB_WIDTH-1:0] A; // A from original $gt/$ge
(* force_downto *)
input [AB_WIDTH-1:0] B; // B from original $gt/$ge
(* force_downto *)
input [LCU_WIDTH-1:0] P; // P of $lcu
(* force_downto *)
input [LCU_WIDTH-1:0] G; // G of $lcu
output Y;
@ -66,6 +75,7 @@ parameter [LCU_WIDTH-1:0] _TECHMAP_CONSTMSK_P_ = 0;
generate
if (AB_WIDTH == 0) begin
(* force_downto *)
wire [LCU_WIDTH-1:0] CO;
$lcu #(.WIDTH(LCU_WIDTH)) _TECHMAP_REPLACE_ (.P(P), .G(G), .CI(CI), .CO(CO));
assign Y = CO[LCU_WIDTH-1];
@ -104,8 +114,10 @@ generate
else begin
// Propagate only if all pairs are equal
// (inconclusive evidence to say A >= B)
(* force_downto *)
wire [LCU_WIDTH-1:0] P_ = {P[LCU_WIDTH-1:1], P[0] & PP};
// Generate if any comparisons call for it
(* force_downto *)
wire [LCU_WIDTH-1:0] G_ = {G[LCU_WIDTH-1:1], G[0] | GG};
end
if (AB_WIDTH == 1)