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Fixups

This commit is contained in:
Akash Levy 2025-09-11 04:37:00 -07:00
parent 54a1862fbe
commit b70aeea35c
1 changed files with 6 additions and 43 deletions
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49
passes/opt/peepopt_addsub_c.pmg
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@ -32,7 +32,7 @@ match addsub2
// Check that b_const and c_const is constant
filter b_const.is_fully_const()
filter port(addsub2, \B).is_fully_const()
index <SigSpec> remove_bottom_padding(port(addsub2, \A)) === addsub1_y
index <SigSpec> port(addsub2, \A) === addsub1_y
endmatch
code
@ -44,9 +44,6 @@ code
SigSpec c_const = port(addsub2, \B);
SigSpec addsub2_y = port(addsub2, \Y);
// Get offset of addsub1 result chunk in addsub2
int offset = GetSize(addsub2_a) - GetSize(addsub1_y);
// Get properties and values of b_const and c_const
// b_const may be coming from the A port
// But it is an RTLIL invariant that A_SIGNED equals B_SIGNED
@ -54,45 +51,19 @@ code
bool c_const_signed = addsub2->getParam(ID::B_SIGNED).as_bool();
int b_const_int = b_const.as_int(b_const_signed);
int c_const_int = c_const.as_int(c_const_signed);
int b_const_int_shifted = b_const_int << offset;
// Helper lambdas for two's complement math
auto sign2sComplement = [](auto value, int numBits) {
if (value & (1 << (numBits - 1))) {
return -1;
} else {
return 1;
}
};
auto twosComplement = [](auto value, int numBits) {
if (value & (1 << (numBits - 1))) {
return (~value) + 1; // invert bits before adding 1
} else {
return value;
}
};
// Two's complement conversion
if (b_const_signed)
b_const_int = sign2sComplement(b_const_int, GetSize(b_const)) * twosComplement(b_const_int, GetSize(b_const));
if (c_const_signed)
c_const_int = sign2sComplement(c_const_int, GetSize(c_const)) * twosComplement(c_const_int, GetSize(c_const));
// Calculate the constant and compress the width to fit the value
Const const_value;
Const b_const_actual;
b_const_actual = b_const_int_shifted;
b_const_actual.compress(b_const_signed);
if (addsub1->type == $add)
if (addsub2->type == $add)
const_value = b_const_int_shifted + c_const_int;
const_value = b_const_int + c_const_int;
else
const_value = b_const_int_shifted - c_const_int;
const_value = b_const_int - c_const_int;
else
if (addsub2->type == $add)
const_value = b_const_int_shifted - c_const_int;
const_value = b_const_int - c_const_int;
else
const_value = b_const_int_shifted + c_const_int;
const_value = b_const_int + c_const_int;
const_value.compress(b_const_signed | c_const_signed);
// Integer values should be lesser than 32 bits
@ -102,15 +73,7 @@ code
reject;
if (GetSize(b_const) > 32)
reject;
if (GetSize(c_const) + offset > 32)
reject;
// // Check for potential overflow
// if (std::max(GetSize(b_const_actual), GetSize(a)) + 1 > GetSize(addsub1_y))
// reject;
// Check that there are only zeros before offset
if (offset < 0 || !addsub2_a.extract(0, offset).is_fully_zero())
if (GetSize(c_const) > 32)
reject;
// Reuse/create new cell to drive the rewritten equation