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Improve rules for shifting behaviour

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Example:
x: u64 = 123;
assert(x >> 64 == 0); // In C this would be 123 because (64 & 0b111111) == 0

a: u64 123;
assert(a << 64 == 0); // In C this would be 123 because (64 & 0b111111) == 0
This commit is contained in:
gingerBill
2020-05-31 13:50:17 +01:00
parent 8057af9e09
commit bf5ce04b24
2 changed files with 59 additions and 13 deletions
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32
src/ir.cpp
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@@ -4499,11 +4499,35 @@ irValue *ir_emit_arith(irProcedure *proc, TokenKind op, irValue *left, irValue *
handle_op:
switch (op) {
case Token_Shl:
case Token_Shr:
left = ir_emit_conv(proc, left, type);
right = ir_emit_conv(proc, right, type);
{
left = ir_emit_conv(proc, left, type);
right = ir_emit_conv(proc, right, type);
ir_emit(proc, ir_instr_binary_op(proc, op, left, right, type));
break;
irValue *bits = right;
irValue *max = ir_value_constant(type, exact_value_i64(8*type_size_of(type) - 1));
irValue *less_equal_width = ir_emit(proc, ir_instr_binary_op(proc, Token_LtEq, bits, max, t_llvm_bool));
irValue *zero = ir_value_constant(type, exact_value_i64(0));
irValue *res = ir_emit(proc, ir_instr_binary_op(proc, op, left, bits, type));
return ir_emit_select(proc, less_equal_width, res, zero);
}
case Token_Shr:
{
left = ir_emit_conv(proc, left, type);
right = ir_emit_conv(proc, right, type);
bool is_unsigned = is_type_unsigned(ir_type(left));
irValue *bits = right;
irValue *max = ir_value_constant(type, exact_value_i64(8*type_size_of(type) - 1));
irValue *less_equal_width = ir_emit(proc, ir_instr_binary_op(proc, Token_LtEq, bits, max, t_llvm_bool));
bits = ir_emit_select(proc, less_equal_width, bits, max);
return ir_emit(proc, ir_instr_binary_op(proc, op, left, bits, type));
}
case Token_AndNot: {
// NOTE(bill): x &~ y == x & (~y) == x & (y ~ -1)