diff options
| -rw-r--r-- | passes/pmgen/peepopt_shiftmul.pmg | 15 | ||||
| -rw-r--r-- | tests/simple/peepopt.v | 4 |
2 files changed, 15 insertions, 4 deletions
diff --git a/passes/pmgen/peepopt_shiftmul.pmg b/passes/pmgen/peepopt_shiftmul.pmg index fe861b728..6adab4e5f 100644 --- a/passes/pmgen/peepopt_shiftmul.pmg +++ b/passes/pmgen/peepopt_shiftmul.pmg @@ -1,4 +1,7 @@ pattern shiftmul +// +// Optimize mul+shift pairs that result from expressions such as foo[s*W+:W] +// state <SigSpec> shamt @@ -49,12 +52,16 @@ code if (GetSize(port(shift, \Y)) > const_factor) reject; + int factor_bits = ceil_log2(const_factor); + SigSpec mul_din = port(mul, const_factor_port == \A ? \B : \A); + + if (GetSize(shamt) < factor_bits+GetSize(mul_din)) + reject; + did_something = true; log("shiftmul pattern in %s: shift=%s, mul=%s\n", log_id(module), log_id(shift), log_id(mul)); - int new_const_factor_log2 = ceil_log2(const_factor); - int new_const_factor = 1 << new_const_factor_log2; - + int new_const_factor = 1 << factor_bits; SigSpec padding(State::Sx, new_const_factor-const_factor); SigSpec old_a = port(shift, \A), new_a; int trunc = 0; @@ -73,7 +80,7 @@ code if (trunc > 0) new_a.remove(GetSize(new_a)-trunc, trunc); - SigSpec new_b = {port(mul, const_factor_port == \A ? \B : \A), SigSpec(State::S0, new_const_factor_log2)}; + SigSpec new_b = {mul_din, SigSpec(State::S0, factor_bits)}; if (param(shift, \B_SIGNED).as_bool()) new_b.append(State::S0); diff --git a/tests/simple/peepopt.v b/tests/simple/peepopt.v index b27b9fe57..1bf427897 100644 --- a/tests/simple/peepopt.v +++ b/tests/simple/peepopt.v @@ -2,6 +2,10 @@ module peepopt_shiftmul_0 #(parameter N=3, parameter W=3) (input [N*W-1:0] i, in assign o = i[s*W+:W]; endmodule +module peepopt_shiftmul_1 (output y, input [2:0] w); +assign y = 1'b1 >> (w * (3'b110)); +endmodule + module peepopt_muldiv_0(input [1:0] i, output [1:0] o); wire [3:0] t; assign t = i * 3; |