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</pre><pre class="rust"><code><span class="kw">use </span>std::collections::HashMap;
<span class="kw">use </span><span class="kw">crate</span>::llvm::{FnValue, FunctionPassManager, IRBuilder, Module, Value};
<span class="kw">use </span><span class="kw">crate</span>::parser::{ExprAST, FunctionAST, PrototypeAST};
<span class="kw">use </span><span class="kw">crate</span>::Either;
<span class="kw">type </span>CodegenResult<T> = <span class="prelude-ty">Result</span><T, String>;
<span class="doccomment">/// Code generator from kaleidoscope AST to LLVM IR.
</span><span class="kw">pub struct </span>Codegen<<span class="lifetime">'llvm</span>, <span class="lifetime">'a</span>> {
module: <span class="kw-2">&</span><span class="lifetime">'llvm </span>Module,
builder: <span class="kw-2">&</span><span class="lifetime">'a </span>IRBuilder<<span class="lifetime">'llvm</span>>,
fpm: <span class="kw-2">&</span><span class="lifetime">'a </span>FunctionPassManager<<span class="lifetime">'llvm</span>>,
fn_protos: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>HashMap<String, PrototypeAST>,
}
<span class="kw">impl</span><<span class="lifetime">'llvm</span>, <span class="lifetime">'a</span>> Codegen<<span class="lifetime">'llvm</span>, <span class="lifetime">'a</span>> {
<span class="doccomment">/// Compile either a [`PrototypeAST`] or a [`FunctionAST`] into the LLVM `module`.
</span><span class="kw">pub fn </span>compile(
module: <span class="kw-2">&</span><span class="lifetime">'llvm </span>Module,
fn_protos: <span class="kw-2">&mut </span>HashMap<String, PrototypeAST>,
compilee: Either<<span class="kw-2">&</span>PrototypeAST, <span class="kw-2">&</span>FunctionAST>,
) -> CodegenResult<FnValue<<span class="lifetime">'llvm</span>>> {
<span class="kw">let </span><span class="kw-2">mut </span>cg = Codegen {
module,
builder: <span class="kw-2">&</span>IRBuilder::with_ctx(module),
fpm: <span class="kw-2">&</span>FunctionPassManager::with_ctx(module),
fn_protos,
};
<span class="kw">let </span><span class="kw-2">mut </span>variables = HashMap::new();
<span class="kw">match </span>compilee {
Either::A(proto) => <span class="prelude-val">Ok</span>(cg.codegen_prototype(proto)),
Either::B(func) => cg.codegen_function(func, <span class="kw-2">&mut </span>variables),
}
}
<span class="kw">fn </span>codegen_expr(
<span class="kw-2">&</span><span class="self">self</span>,
expr: <span class="kw-2">&</span>ExprAST,
named_values: <span class="kw-2">&mut </span>HashMap<String, Value<<span class="lifetime">'llvm</span>>>,
) -> CodegenResult<Value<<span class="lifetime">'llvm</span>>> {
<span class="kw">match </span>expr {
ExprAST::Number(num) => <span class="prelude-val">Ok</span>(<span class="self">self</span>.module.type_f64().const_f64(<span class="kw-2">*</span>num)),
ExprAST::Variable(name) => <span class="kw">match </span>named_values.get(name.as_str()) {
<span class="prelude-val">Some</span>(value) => <span class="prelude-val">Ok</span>(<span class="kw-2">*</span>value),
<span class="prelude-val">None </span>=> <span class="prelude-val">Err</span>(<span class="string">"Unknown variable name"</span>.into()),
},
ExprAST::Binary(binop, lhs, rhs) => {
<span class="kw">let </span>l = <span class="self">self</span>.codegen_expr(lhs, named_values)<span class="question-mark">?</span>;
<span class="kw">let </span>r = <span class="self">self</span>.codegen_expr(rhs, named_values)<span class="question-mark">?</span>;
<span class="kw">match </span>binop {
<span class="string">'+' </span>=> <span class="prelude-val">Ok</span>(<span class="self">self</span>.builder.fadd(l, r)),
<span class="string">'-' </span>=> <span class="prelude-val">Ok</span>(<span class="self">self</span>.builder.fsub(l, r)),
<span class="string">'*' </span>=> <span class="prelude-val">Ok</span>(<span class="self">self</span>.builder.fmul(l, r)),
<span class="string">'<' </span>=> {
<span class="kw">let </span>res = <span class="self">self</span>.builder.fcmpult(l, r);
<span class="comment">// Turn bool into f64.
</span><span class="prelude-val">Ok</span>(<span class="self">self</span>.builder.uitofp(res, <span class="self">self</span>.module.type_f64()))
}
<span class="kw">_ </span>=> <span class="prelude-val">Err</span>(<span class="string">"invalid binary operator"</span>.into()),
}
}
ExprAST::Call(callee, args) => <span class="kw">match </span><span class="self">self</span>.get_function(callee) {
<span class="prelude-val">Some</span>(callee) => {
<span class="kw">if </span>callee.args() != args.len() {
<span class="kw">return </span><span class="prelude-val">Err</span>(<span class="string">"Incorrect # arguments passed"</span>.into());
}
<span class="comment">// Generate code for function argument expressions.
</span><span class="kw">let </span><span class="kw-2">mut </span>args: Vec<Value<<span class="lifetime">'_</span>>> = args
.iter()
.map(|arg| <span class="self">self</span>.codegen_expr(arg, named_values))
.collect::<CodegenResult<<span class="kw">_</span>>>()<span class="question-mark">?</span>;
<span class="prelude-val">Ok</span>(<span class="self">self</span>.builder.call(callee, <span class="kw-2">&mut </span>args))
}
<span class="prelude-val">None </span>=> <span class="prelude-val">Err</span>(<span class="string">"Unknown function referenced"</span>.into()),
},
ExprAST::If { cond, then, else_ } => {
<span class="comment">// For 'if' expressions we are building the following CFG.
//
// ; cond
// br
// |
// +-----+------+
// v v
// ; then ; else
// | |
// +-----+------+
// v
// ; merge
// phi then, else
// ret phi
</span><span class="kw">let </span>cond_v = {
<span class="comment">// Codgen 'cond' expression.
</span><span class="kw">let </span>v = <span class="self">self</span>.codegen_expr(cond, named_values)<span class="question-mark">?</span>;
<span class="comment">// Compare 'v' against '0' as 'one = ordered not equal'.
</span><span class="self">self</span>.builder
.fcmpone(v, <span class="self">self</span>.module.type_f64().const_f64(<span class="number">0f64</span>))
};
<span class="comment">// Get the function we are currently inserting into.
</span><span class="kw">let </span>the_function = <span class="self">self</span>.builder.get_insert_block().get_parent();
<span class="comment">// Create basic blocks for the 'then' / 'else' expressions as well as the return
// instruction ('merge').
//
// Append the 'then' basic block to the function, don't insert the 'else' and
// 'merge' basic blocks yet.
</span><span class="kw">let </span>then_bb = <span class="self">self</span>.module.append_basic_block(the_function);
<span class="kw">let </span>else_bb = <span class="self">self</span>.module.create_basic_block();
<span class="kw">let </span>merge_bb = <span class="self">self</span>.module.create_basic_block();
<span class="comment">// Create a conditional branch based on the result of the 'cond' expression.
</span><span class="self">self</span>.builder.cond_br(cond_v, then_bb, else_bb);
<span class="comment">// Move to 'then' basic block and codgen the 'then' expression.
</span><span class="self">self</span>.builder.pos_at_end(then_bb);
<span class="kw">let </span>then_v = <span class="self">self</span>.codegen_expr(then, named_values)<span class="question-mark">?</span>;
<span class="comment">// Create unconditional branch to 'merge' block.
</span><span class="self">self</span>.builder.br(merge_bb);
<span class="comment">// Update reference to current basic block (in case the 'then' expression added new
// basic blocks).
</span><span class="kw">let </span>then_bb = <span class="self">self</span>.builder.get_insert_block();
<span class="comment">// Now append the 'else' basic block to the function.
</span>the_function.append_basic_block(else_bb);
<span class="comment">// Move to 'else' basic block and codgen the 'else' expression.
</span><span class="self">self</span>.builder.pos_at_end(else_bb);
<span class="kw">let </span>else_v = <span class="self">self</span>.codegen_expr(else_, named_values)<span class="question-mark">?</span>;
<span class="comment">// Create unconditional branch to 'merge' block.
</span><span class="self">self</span>.builder.br(merge_bb);
<span class="comment">// Update reference to current basic block (in case the 'else' expression added new
// basic blocks).
</span><span class="kw">let </span>else_bb = <span class="self">self</span>.builder.get_insert_block();
<span class="comment">// Now append the 'merge' basic block to the function.
</span>the_function.append_basic_block(merge_bb);
<span class="comment">// Move to 'merge' basic block.
</span><span class="self">self</span>.builder.pos_at_end(merge_bb);
<span class="comment">// Codegen the phi node returning the appropriate value depending on the branch
// condition.
</span><span class="kw">let </span>phi = <span class="self">self</span>.builder.phi(
<span class="self">self</span>.module.type_f64(),
<span class="kw-2">&</span>[(then_v, then_bb), (else_v, else_bb)],
);
<span class="prelude-val">Ok</span>(<span class="kw-2">*</span>phi)
}
ExprAST::For {
var,
start,
end,
step,
body,
} => {
<span class="comment">// For 'for' expression we build the following structure.
//
// entry:
// init = start expression
// br loop
// loop:
// i = phi [%init, %entry], [%new_i, %loop]
// ; loop body ...
// new_i = increment %i by step expression
// ; check end condition and branch
// end:
// Compute initial value for the loop variable.
</span><span class="kw">let </span>start_val = <span class="self">self</span>.codegen_expr(start, named_values)<span class="question-mark">?</span>;
<span class="kw">let </span>the_function = <span class="self">self</span>.builder.get_insert_block().get_parent();
<span class="comment">// Get current basic block (used in the loop variable phi node).
</span><span class="kw">let </span>entry_bb = <span class="self">self</span>.builder.get_insert_block();
<span class="comment">// Add new basic block to emit loop body.
</span><span class="kw">let </span>loop_bb = <span class="self">self</span>.module.append_basic_block(the_function);
<span class="self">self</span>.builder.br(loop_bb);
<span class="self">self</span>.builder.pos_at_end(loop_bb);
<span class="comment">// Build phi not to pick loop variable in case we come from the 'entry' block.
// Which is the case when we enter the loop for the first time.
// We will add another incoming value once we computed the updated loop variable
// below.
</span><span class="kw">let </span>variable = <span class="self">self
</span>.builder
.phi(<span class="self">self</span>.module.type_f64(), <span class="kw-2">&</span>[(start_val, entry_bb)]);
<span class="comment">// Insert the loop variable into the named values map that it can be referenced
// from the body as well as the end condition.
// In case the loop variable shadows an existing variable remember the shared one.
</span><span class="kw">let </span>old_val = named_values.insert(var.into(), <span class="kw-2">*</span>variable);
<span class="comment">// Generate the loop body.
</span><span class="self">self</span>.codegen_expr(body, named_values)<span class="question-mark">?</span>;
<span class="comment">// Generate step value expression if available else use '1'.
</span><span class="kw">let </span>step_val = <span class="kw">if let </span><span class="prelude-val">Some</span>(step) = step {
<span class="self">self</span>.codegen_expr(step, named_values)<span class="question-mark">?
</span>} <span class="kw">else </span>{
<span class="self">self</span>.module.type_f64().const_f64(<span class="number">1f64</span>)
};
<span class="comment">// Increment loop variable.
</span><span class="kw">let </span>next_var = <span class="self">self</span>.builder.fadd(<span class="kw-2">*</span>variable, step_val);
<span class="comment">// Generate the loop end condition.
</span><span class="kw">let </span>end_cond = <span class="self">self</span>.codegen_expr(end, named_values)<span class="question-mark">?</span>;
<span class="kw">let </span>end_cond = <span class="self">self
</span>.builder
.fcmpone(end_cond, <span class="self">self</span>.module.type_f64().const_f64(<span class="number">0f64</span>));
<span class="comment">// Get current basic block.
</span><span class="kw">let </span>loop_end_bb = <span class="self">self</span>.builder.get_insert_block();
<span class="comment">// Add new basic block following the loop.
</span><span class="kw">let </span>after_bb = <span class="self">self</span>.module.append_basic_block(the_function);
<span class="comment">// Register additional incoming value for the loop variable. This will choose the
// updated loop variable if we are iterating in the loop.
</span>variable.add_incoming(next_var, loop_end_bb);
<span class="comment">// Branch depending on the loop end condition.
</span><span class="self">self</span>.builder.cond_br(end_cond, loop_bb, after_bb);
<span class="self">self</span>.builder.pos_at_end(after_bb);
<span class="comment">// Restore the shadowed variable if there was one.
</span><span class="kw">if let </span><span class="prelude-val">Some</span>(old_val) = old_val {
<span class="comment">// We inserted 'var' above so it must exist.
</span><span class="kw-2">*</span>named_values.get_mut(var).unwrap() = old_val;
} <span class="kw">else </span>{
named_values.remove(var);
}
<span class="comment">// Loops just always return 0.
</span><span class="prelude-val">Ok</span>(<span class="self">self</span>.module.type_f64().const_f64(<span class="number">0f64</span>))
}
}
}
<span class="kw">fn </span>codegen_prototype(<span class="kw-2">&</span><span class="self">self</span>, PrototypeAST(name, args): <span class="kw-2">&</span>PrototypeAST) -> FnValue<<span class="lifetime">'llvm</span>> {
<span class="kw">let </span>type_f64 = <span class="self">self</span>.module.type_f64();
<span class="kw">let </span><span class="kw-2">mut </span>doubles = Vec::new();
doubles.resize(args.len(), type_f64);
<span class="comment">// Build the function type: fn(f64, f64, ..) -> f64
</span><span class="kw">let </span>ft = <span class="self">self</span>.module.type_fn(<span class="kw-2">&mut </span>doubles, type_f64);
<span class="comment">// Create the function declaration.
</span><span class="kw">let </span>f = <span class="self">self</span>.module.add_fn(name, ft);
<span class="comment">// Set the names of the function arguments.
</span><span class="kw">for </span>idx <span class="kw">in </span><span class="number">0</span>..f.args() {
f.arg(idx).set_name(<span class="kw-2">&</span>args[idx]);
}
f
}
<span class="kw">fn </span>codegen_function(
<span class="kw-2">&mut </span><span class="self">self</span>,
FunctionAST(proto, body): <span class="kw-2">&</span>FunctionAST,
named_values: <span class="kw-2">&mut </span>HashMap<String, Value<<span class="lifetime">'llvm</span>>>,
) -> CodegenResult<FnValue<<span class="lifetime">'llvm</span>>> {
<span class="comment">// Insert the function prototype into the `fn_protos` map to keep track for re-generating
// declarations in other modules.
</span><span class="self">self</span>.fn_protos.insert(proto.<span class="number">0</span>.clone(), proto.clone());
<span class="kw">let </span>the_function = <span class="self">self</span>.get_function(<span class="kw-2">&</span>proto.<span class="number">0</span>)
.expect(<span class="string">"If proto not already generated, get_function will do for us since we updated fn_protos before-hand!"</span>);
<span class="kw">if </span>the_function.basic_blocks() > <span class="number">0 </span>{
<span class="kw">return </span><span class="prelude-val">Err</span>(<span class="string">"Function cannot be redefined."</span>.into());
}
<span class="comment">// Create entry basic block to insert code.
</span><span class="kw">let </span>bb = <span class="self">self</span>.module.append_basic_block(the_function);
<span class="self">self</span>.builder.pos_at_end(bb);
<span class="comment">// New scope, clear the map with the function args.
</span>named_values.clear();
<span class="comment">// Update the map with the current functions args.
</span><span class="kw">for </span>idx <span class="kw">in </span><span class="number">0</span>..the_function.args() {
<span class="kw">let </span>arg = the_function.arg(idx);
named_values.insert(arg.get_name().into(), arg);
}
<span class="comment">// Codegen function body.
</span><span class="kw">if let </span><span class="prelude-val">Ok</span>(ret) = <span class="self">self</span>.codegen_expr(body, named_values) {
<span class="self">self</span>.builder.ret(ret);
<span class="macro">assert!</span>(the_function.verify());
<span class="comment">// Run the optimization passes on the function.
</span><span class="self">self</span>.fpm.run(the_function);
<span class="prelude-val">Ok</span>(the_function)
} <span class="kw">else </span>{
<span class="macro">todo!</span>(<span class="string">"Failed to codegen function body, erase from module!"</span>);
}
}
<span class="doccomment">/// Lookup function with `name` in the LLVM module and return the corresponding value reference.
/// If the function is not available in the module, check if the prototype is known and codegen
/// it.
/// Return [`None`] if the prototype is not known.
</span><span class="kw">fn </span>get_function(<span class="kw-2">&</span><span class="self">self</span>, name: <span class="kw-2">&</span>str) -> <span class="prelude-ty">Option</span><FnValue<<span class="lifetime">'llvm</span>>> {
<span class="kw">let </span>callee = <span class="kw">match </span><span class="self">self</span>.module.get_fn(name) {
<span class="prelude-val">Some</span>(callee) => callee,
<span class="prelude-val">None </span>=> {
<span class="kw">let </span>proto = <span class="self">self</span>.fn_protos.get(name)<span class="question-mark">?</span>;
<span class="self">self</span>.codegen_prototype(proto)
}
};
<span class="prelude-val">Some</span>(callee)
}
}
</code></pre></div>
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