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| author | Clifford Wolf <clifford@clifford.at> | 2019-05-28 15:33:47 +0200 |
|---|---|---|
| committer | Clifford Wolf <clifford@clifford.at> | 2019-05-28 17:17:56 +0200 |
| commit | cb285e4b87112779efe84a7b6c5ae4a76a69ae01 (patch) | |
| tree | f5fa3daeda4b05eb8833330e5a8c09f4d33487d3 /passes/pmgen | |
| parent | 2a11c48782d31cd6f9c181f7ff52984cc2ae0351 (diff) | |
| download | yosys-cb285e4b87112779efe84a7b6c5ae4a76a69ae01.tar.gz yosys-cb285e4b87112779efe84a7b6c5ae4a76a69ae01.tar.bz2 yosys-cb285e4b87112779efe84a7b6c5ae4a76a69ae01.zip | |
Do not use shiftmul peepopt pattern when mul result is truncated, fixes #1047
Signed-off-by: Clifford Wolf <clifford@clifford.at>
Diffstat (limited to 'passes/pmgen')
| -rw-r--r-- | passes/pmgen/peepopt_shiftmul.pmg | 15 |
1 files changed, 11 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); |