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