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71 lines
1.7 KiB
Text
71 lines
1.7 KiB
Text
pattern muldiv_c
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//
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// Transforms mul->div into div->mul when b and c are divisible constants:
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// y = (a * b_const) / c_const ===> a * (b_const / c_const)
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//
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state <SigSpec> a b_const mul_y
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match mul
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// Select multiplier
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select mul->type == $mul
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endmatch
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code a b_const mul_y
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printf("CODING MUL!!!\n");
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// Get multiplier signals
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a = port(mul, \A);
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b_const = port(mul, \B);
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mul_y = port(mul, \Y);
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// Fanout of each multiplier Y bit should be 1 (no bit-split)
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for (auto bit : mul_y)
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if (nusers(bit) != 2)
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reject;
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// A and B can be interchanged
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branch;
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std::swap(a, b_const);
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endcode
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match div
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// Select div of form (a * b_const) / c_const
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select div->type == $div
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index <SigSpec> port(div, \A) === port(mul, \Y)
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// Check that b_const and c_const is constant
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filter port(mul, \B).is_fully_const()
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filter port(div, \B).is_fully_const()
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endmatch
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code
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printf("CODING DIV!!!\n");
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// Get div signals
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SigSpec c_const = port(div, \B);
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SigSpec div_y = port(div, \Y);
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// Get properties and values of b_const and c_const
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int b_const_width = mul->getParam(ID::B_WIDTH).as_int();
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bool b_const_signed = mul->getParam(ID::B_SIGNED).as_bool();
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bool c_const_signed = div->getParam(ID::B_SIGNED).as_bool();
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int b_const_int = b_const.as_int(b_const_signed);
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int c_const_int = c_const.as_int(c_const_signed);
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// Check that b is divisible by c
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if (b_const_int % c_const_int != 0)
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reject;
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// Rewire to only keep multiplier
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mul->setPort(\B, Const(b_const_int / c_const_int, b_const_width));
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mul->setPort(\Y, div_y);
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// Remove divider
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autoremove(div);
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// Log, fixup, accept
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log("muldiv_const pattern in %s: mul=%s, div=%s\n", log_id(module), log_id(mul), log_id(div));
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mul->fixup_parameters();
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accept;
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endcode
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