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fix a few bugs in the functional backend and refactor the testing

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This commit is contained in:
Emily Schmidt 2024-07-16 17:55:26 +01:00
parent 674e6d201d
commit 6922633b0b
6 changed files with 366 additions and 270 deletions
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40
kernel/functionalir.cc
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@ -226,26 +226,36 @@ public:
T b = extend(inputs.at(ID(B)), b_width, width, is_signed);
if(is_signed) {
if(cellType == ID($div)) {
// divide absolute values, then flip the sign if input signs differ
// but extend the width first, to handle the case (most negative value) / (-1)
T abs_y = factory.unsigned_div(abs(a, width), abs(b, width), width);
T out_sign = factory.not_equal(sign(a, width), sign(b, width), 1);
return neg_if(extend(abs_y, width, y_width, true), y_width, out_sign);
return neg_if(extend(abs_y, width, y_width, false), y_width, out_sign);
} else if(cellType == ID($mod)) {
// similar to division but output sign == divisor sign
T abs_y = factory.unsigned_mod(abs(a, width), abs(b, width), width);
return neg_if(extend(abs_y, width, y_width, true), y_width, sign(a, width));
return neg_if(extend(abs_y, width, y_width, false), y_width, sign(a, width));
} else if(cellType == ID($divfloor)) {
// if b is negative, flip both signs so that b is positive
T b_sign = sign(b, width);
T a1 = neg_if(a, width, b_sign);
T b1 = neg_if(b, width, b_sign);
T a1_sign = sign(a1, width);
// if a is now negative, calculate ~((~a) / b) = -((-a - 1) / b + 1)
// which equals the negative of (-a) / b with rounding up rather than down
// note that to handle the case where a = most negative value properly,
// we have to calculate a1_sign from the original values rather than using sign(a1, width)
T a1_sign = factory.bitwise_and(factory.not_equal(sign(a, width), sign(b, width), 1), reduce_or(a, width), 1);
T a2 = factory.mux(a1, factory.bitwise_not(a1, width), a1_sign, width);
T y1 = factory.unsigned_div(a2, b1, width);
T y2 = factory.mux(y1, factory.bitwise_not(y1, width), a1_sign, width);
return extend(y2, width, y_width, true);
T y2 = extend(y1, width, y_width, false);
return factory.mux(y2, factory.bitwise_not(y2, y_width), a1_sign, y_width);
} else if(cellType == ID($modfloor)) {
// calculate |a| % |b| and then subtract from |b| if input signs differ and the remainder is non-zero
T abs_b = abs(b, width);
T abs_y = factory.unsigned_mod(abs(a, width), abs_b, width);
T flip_y = factory.bitwise_and(factory.bitwise_xor(sign(a, width), sign(b, width), 1), factory.reduce_or(abs_y, width), 1);
T y_flipped = factory.mux(abs_y, factory.sub(abs_b, abs_y, width), flip_y, width);
// since y_flipped is strictly less than |b|, the top bit is always 0 and we can just sign extend the flipped result
T y = neg_if(y_flipped, width, sign(b, b_width));
return extend(y, width, y_width, true);
} else
@ -261,22 +271,8 @@ public:
} else if (cellType == ID($lut)) {
int width = parameters.at(ID(WIDTH)).as_int();
Const lut_table = parameters.at(ID(LUT));
T a = inputs.at(ID(A));
// Output initialization
T y = factory.constant(Const(0, 1));
// Iterate over each possible input combination
for (int i = 0; i < (1 << width); ++i) {
// Create a constant representing the value of i
T i_val = factory.constant(Const(i, width));
// Check if the input matches this value
T match = factory.equal(a, i_val, width);
// Get the corresponding LUT value
bool lut_val = lut_table.bits[i] == State::S1;
T lut_output = factory.constant(Const(lut_val, 1));
// Use a multiplexer to select the correct output based on the match
y = factory.mux(y, lut_output, match, 1);
}
return y;
lut_table.extu(1 << width);
return handle_bmux(factory.constant(lut_table), inputs.at(ID(A)), 1 << width, 0, 1, width, width);
} else if (cellType == ID($bwmux)) {
int width = parameters.at(ID(WIDTH)).as_int();
T a = inputs.at(ID(A));
@ -526,7 +522,7 @@ void FunctionalIR::topological_sort() {
if(scc) log_error("combinational loops, aborting\n");
}
IdString merge_name(IdString a, IdString b) {
static IdString merge_name(IdString a, IdString b) {
if(a[0] == '$' && b[0] == '\\')
return b;
else