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-rw-r--r--techlibs/common/Makefile.inc2
-rw-r--r--techlibs/common/cmp2lut.v105
-rw-r--r--techlibs/common/prep.cc2
-rw-r--r--techlibs/common/synth.cc48
4 files changed, 148 insertions, 9 deletions
diff --git a/techlibs/common/Makefile.inc b/techlibs/common/Makefile.inc
index 70074f653..0e05620bc 100644
--- a/techlibs/common/Makefile.inc
+++ b/techlibs/common/Makefile.inc
@@ -26,5 +26,5 @@ $(eval $(call add_share_file,share,techlibs/common/pmux2mux.v))
$(eval $(call add_share_file,share,techlibs/common/adff2dff.v))
$(eval $(call add_share_file,share,techlibs/common/dff2ff.v))
$(eval $(call add_share_file,share,techlibs/common/gate2lut.v))
+$(eval $(call add_share_file,share,techlibs/common/cmp2lut.v))
$(eval $(call add_share_file,share,techlibs/common/cells.lib))
-
diff --git a/techlibs/common/cmp2lut.v b/techlibs/common/cmp2lut.v
new file mode 100644
index 000000000..8aa1eb957
--- /dev/null
+++ b/techlibs/common/cmp2lut.v
@@ -0,0 +1,105 @@
+// Certain arithmetic operations between a signal of width n and a constant can be directly mapped
+// to a single k-LUT (where n <= k). This is preferable to normal alumacc techmapping process
+// because for many targets, arithmetic techmapping creates hard logic (such as carry cells) which often
+// cannot be optimized further.
+//
+// TODO: Currently, only comparisons with 1-bit output are mapped. Potentially, all arithmetic cells
+// with n <= k inputs should be techmapped in this way, because this shortens the critical path
+// from n to 1 by avoiding carry chains.
+
+(* techmap_celltype = "$eq $ne $lt $le $gt $ge" *)
+module _90_lut_cmp_ (A, B, Y);
+
+parameter A_SIGNED = 0;
+parameter B_SIGNED = 0;
+parameter A_WIDTH = 0;
+parameter B_WIDTH = 0;
+parameter Y_WIDTH = 0;
+
+input [A_WIDTH-1:0] A;
+input [B_WIDTH-1:0] B;
+output [Y_WIDTH-1:0] Y;
+
+parameter _TECHMAP_CELLTYPE_ = "";
+
+parameter _TECHMAP_CONSTMSK_A_ = 0;
+parameter _TECHMAP_CONSTVAL_A_ = 0;
+parameter _TECHMAP_CONSTMSK_B_ = 0;
+parameter _TECHMAP_CONSTVAL_B_ = 0;
+
+function automatic integer gen_lut;
+ input integer width;
+ input integer operation;
+ input integer swap;
+ input integer sign;
+ input integer operand;
+ integer n, i_var, i_cst, lhs, rhs, o_bit;
+ begin
+ gen_lut = width'b0;
+ for (n = 0; n < (1 << width); n++) begin
+ if (sign)
+ i_var = n[width-1:0];
+ else
+ i_var = n;
+ i_cst = operand;
+ if (swap) begin
+ lhs = i_cst;
+ rhs = i_var;
+ end else begin
+ lhs = i_var;
+ rhs = i_cst;
+ end
+ if (operation == 0)
+ o_bit = (lhs < rhs);
+ if (operation == 1)
+ o_bit = (lhs <= rhs);
+ if (operation == 2)
+ o_bit = (lhs > rhs);
+ if (operation == 3)
+ o_bit = (lhs >= rhs);
+ if (operation == 4)
+ o_bit = (lhs == rhs);
+ if (operation == 5)
+ o_bit = (lhs != rhs);
+ gen_lut = gen_lut | (o_bit << n);
+ end
+ end
+endfunction
+
+generate
+ if (_TECHMAP_CELLTYPE_ == "$lt")
+ localparam operation = 0;
+ if (_TECHMAP_CELLTYPE_ == "$le")
+ localparam operation = 1;
+ if (_TECHMAP_CELLTYPE_ == "$gt")
+ localparam operation = 2;
+ if (_TECHMAP_CELLTYPE_ == "$ge")
+ localparam operation = 3;
+ if (_TECHMAP_CELLTYPE_ == "$eq")
+ localparam operation = 4;
+ if (_TECHMAP_CELLTYPE_ == "$ne")
+ localparam operation = 5;
+
+ if (A_WIDTH > `LUT_WIDTH || B_WIDTH > `LUT_WIDTH || Y_WIDTH != 1)
+ wire _TECHMAP_FAIL_ = 1;
+ else if (&_TECHMAP_CONSTMSK_B_)
+ \$lut #(
+ .WIDTH(A_WIDTH),
+ .LUT({ gen_lut(A_WIDTH, operation, 0, A_SIGNED && B_SIGNED, _TECHMAP_CONSTVAL_B_) })
+ ) _TECHMAP_REPLACE_ (
+ .A(A),
+ .Y(Y)
+ );
+ else if (&_TECHMAP_CONSTMSK_A_)
+ \$lut #(
+ .WIDTH(B_WIDTH),
+ .LUT({ gen_lut(B_WIDTH, operation, 1, A_SIGNED && B_SIGNED, _TECHMAP_CONSTVAL_A_) })
+ ) _TECHMAP_REPLACE_ (
+ .A(B),
+ .Y(Y)
+ );
+ else
+ wire _TECHMAP_FAIL_ = 1;
+endgenerate
+
+endmodule
diff --git a/techlibs/common/prep.cc b/techlibs/common/prep.cc
index 897f37dbb..86fb4d6c6 100644
--- a/techlibs/common/prep.cc
+++ b/techlibs/common/prep.cc
@@ -153,7 +153,7 @@ struct PrepPass : public ScriptPass
extra_args(args, argidx, design);
if (!design->full_selection())
- log_cmd_error("This comannd only operates on fully selected designs!\n");
+ log_cmd_error("This command only operates on fully selected designs!\n");
log_header(design, "Executing PREP pass.\n");
log_push();
diff --git a/techlibs/common/synth.cc b/techlibs/common/synth.cc
index efb214759..ccfa76e02 100644
--- a/techlibs/common/synth.cc
+++ b/techlibs/common/synth.cc
@@ -51,6 +51,9 @@ struct SynthPass : public ScriptPass
log(" -encfile <file>\n");
log(" passed to 'fsm_recode' via 'fsm'\n");
log("\n");
+ log(" -lut <k>\n");
+ log(" perform synthesis for a k-LUT architecture.\n");
+ log("\n");
log(" -nofsm\n");
log(" do not run FSM optimization\n");
log("\n");
@@ -80,6 +83,7 @@ struct SynthPass : public ScriptPass
string top_module, fsm_opts, memory_opts;
bool autotop, flatten, noalumacc, nofsm, noabc, noshare;
+ int lut;
void clear_flags() YS_OVERRIDE
{
@@ -89,6 +93,7 @@ struct SynthPass : public ScriptPass
autotop = false;
flatten = false;
+ lut = 0;
noalumacc = false;
nofsm = false;
noabc = false;
@@ -130,6 +135,10 @@ struct SynthPass : public ScriptPass
flatten = true;
continue;
}
+ if (args[argidx] == "-lut") {
+ lut = atoi(args[++argidx].c_str());
+ continue;
+ }
if (args[argidx] == "-nofsm") {
nofsm = true;
continue;
@@ -155,7 +164,7 @@ struct SynthPass : public ScriptPass
extra_args(args, argidx, design);
if (!design->full_selection())
- log_cmd_error("This comannd only operates on fully selected designs!\n");
+ log_cmd_error("This command only operates on fully selected designs!\n");
log_header(design, "Executing SYNTH pass.\n");
log_push();
@@ -186,19 +195,23 @@ struct SynthPass : public ScriptPass
{
run("proc");
if (help_mode || flatten)
- run("flatten", "(if -flatten)");
+ run("flatten", " (if -flatten)");
run("opt_expr");
run("opt_clean");
run("check");
run("opt");
run("wreduce");
+ if (help_mode)
+ run("techmap -map +/cmp2lut.v", " (if -lut)");
+ else
+ run(stringf("techmap -map +/cmp2lut.v -D LUT_WIDTH=%d", lut));
if (!noalumacc)
- run("alumacc");
+ run("alumacc", " (unless -noalumacc)");
if (!noshare)
- run("share");
+ run("share", " (unless -noshare)");
run("opt");
if (!nofsm)
- run("fsm" + fsm_opts);
+ run("fsm" + fsm_opts, " (unless -nofsm)");
run("opt -fast");
run("memory -nomap" + memory_opts);
run("opt_clean");
@@ -210,12 +223,33 @@ struct SynthPass : public ScriptPass
run("memory_map");
run("opt -full");
run("techmap");
+ if (help_mode)
+ {
+ run("techmap -map +/gate2lut.v", "(if -noabc and -lut)");
+ run("clean; opt_lut", " (if -noabc and -lut)");
+ }
+ else if (noabc && lut)
+ {
+ run(stringf("techmap -map +/gate2lut.v -D LUT_WIDTH=%d", lut));
+ run("clean; opt_lut");
+ }
run("opt -fast");
if (!noabc) {
#ifdef YOSYS_ENABLE_ABC
- run("abc -fast");
- run("opt -fast");
+ if (help_mode)
+ {
+ run("abc -fast", " (unless -noabc, unless -lut)");
+ run("abc -fast -lut k", "(unless -noabc, if -lut)");
+ }
+ else
+ {
+ if (lut)
+ run(stringf("abc -fast -lut %d", lut));
+ else
+ run("abc -fast");
+ }
+ run("opt -fast", " (unless -noabc)");
#endif
}
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-04-07 17:09:05 +0000