Rename the 'cretonne' crate to 'cretonne-codegen'.
This fixes the next part of #287.
This commit is contained in:
Dan Gohman
683
lib/codegen/src/legalizer/boundary.rs
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683
lib/codegen/src/legalizer/boundary.rs
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@@ -0,0 +1,683 @@
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//! Legalize ABI boundaries.
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//!
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//! This legalizer sub-module contains code for dealing with ABI boundaries:
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//!
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//! - Function arguments passed to the entry block.
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//! - Function arguments passed to call instructions.
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//! - Return values from call instructions.
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//! - Return values passed to return instructions.
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//!
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//! The ABI boundary legalization happens in two phases:
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//!
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//! 1. The `legalize_signatures` function rewrites all the preamble signatures with ABI information
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//! and possibly new argument types. It also rewrites the entry block arguments to match.
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//! 2. The `handle_call_abi` and `handle_return_abi` functions rewrite call and return instructions
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//! to match the new ABI signatures.
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//!
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//! Between the two phases, preamble signatures and call/return arguments don't match. This
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//! intermediate state doesn't type check.
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use abi::{legalize_abi_value, ValueConversion};
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use cursor::{Cursor, FuncCursor};
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use flowgraph::ControlFlowGraph;
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use ir::instructions::CallInfo;
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use ir::{AbiParam, ArgumentLoc, ArgumentPurpose, DataFlowGraph, Ebb, Function, Inst, InstBuilder,
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SigRef, Signature, Type, Value, ValueLoc};
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use isa::TargetIsa;
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use legalizer::split::{isplit, vsplit};
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use std::vec::Vec;
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/// Legalize all the function signatures in `func`.
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///
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/// This changes all signatures to be ABI-compliant with full `ArgumentLoc` annotations. It doesn't
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/// change the entry block arguments, calls, or return instructions, so this can leave the function
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/// in a state with type discrepancies.
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pub fn legalize_signatures(func: &mut Function, isa: &TargetIsa) {
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isa.legalize_signature(&mut func.signature, true);
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func.signature.compute_argument_bytes();
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for sig_data in func.dfg.signatures.values_mut() {
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isa.legalize_signature(sig_data, false);
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sig_data.compute_argument_bytes();
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}
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if let Some(entry) = func.layout.entry_block() {
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legalize_entry_params(func, entry);
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spill_entry_params(func, entry);
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}
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}
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/// Legalize the entry block parameters after `func`'s signature has been legalized.
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///
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/// The legalized signature may contain more parameters than the original signature, and the
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/// parameter types have been changed. This function goes through the parameters of the entry EBB
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/// and replaces them with parameters of the right type for the ABI.
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///
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/// The original entry EBB parameters are computed from the new ABI parameters by code inserted at
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/// the top of the entry block.
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fn legalize_entry_params(func: &mut Function, entry: Ebb) {
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let mut has_sret = false;
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let mut has_link = false;
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let mut has_vmctx = false;
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let mut has_sigid = false;
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// Insert position for argument conversion code.
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// We want to insert instructions before the first instruction in the entry block.
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// If the entry block is empty, append instructions to it instead.
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let mut pos = FuncCursor::new(func).at_first_inst(entry);
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// Keep track of the argument types in the ABI-legalized signature.
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let mut abi_arg = 0;
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// Process the EBB parameters one at a time, possibly replacing one argument with multiple new
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// ones. We do this by detaching the entry EBB parameters first.
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let ebb_params = pos.func.dfg.detach_ebb_params(entry);
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let mut old_arg = 0;
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while let Some(arg) = ebb_params.get(old_arg, &pos.func.dfg.value_lists) {
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old_arg += 1;
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let abi_type = pos.func.signature.params[abi_arg];
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let arg_type = pos.func.dfg.value_type(arg);
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if arg_type == abi_type.value_type {
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// No value translation is necessary, this argument matches the ABI type.
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// Just use the original EBB argument value. This is the most common case.
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pos.func.dfg.attach_ebb_param(entry, arg);
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match abi_type.purpose {
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ArgumentPurpose::Normal => {}
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ArgumentPurpose::FramePointer => {}
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ArgumentPurpose::CalleeSaved => {}
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ArgumentPurpose::StructReturn => {
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debug_assert!(!has_sret, "Multiple sret arguments found");
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has_sret = true;
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}
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ArgumentPurpose::VMContext => {
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debug_assert!(!has_vmctx, "Multiple vmctx arguments found");
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has_vmctx = true;
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}
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ArgumentPurpose::SignatureId => {
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debug_assert!(!has_sigid, "Multiple sigid arguments found");
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has_sigid = true;
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}
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_ => panic!("Unexpected special-purpose arg {}", abi_type),
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}
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abi_arg += 1;
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} else {
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// Compute the value we want for `arg` from the legalized ABI parameters.
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let mut get_arg = |func: &mut Function, ty| {
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let abi_type = func.signature.params[abi_arg];
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debug_assert_eq!(
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abi_type.purpose,
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ArgumentPurpose::Normal,
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"Can't legalize special-purpose argument"
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);
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if ty == abi_type.value_type {
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abi_arg += 1;
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Ok(func.dfg.append_ebb_param(entry, ty))
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} else {
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Err(abi_type)
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}
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};
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let converted = convert_from_abi(&mut pos, arg_type, Some(arg), &mut get_arg);
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// The old `arg` is no longer an attached EBB argument, but there are probably still
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// uses of the value.
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debug_assert_eq!(pos.func.dfg.resolve_aliases(arg), converted);
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}
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}
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// The legalized signature may contain additional parameters representing special-purpose
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// registers.
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for &arg in &pos.func.signature.params[abi_arg..] {
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match arg.purpose {
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// Any normal parameters should have been processed above.
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ArgumentPurpose::Normal => {
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panic!("Leftover arg: {}", arg);
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}
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// The callee-save parameters should not appear until after register allocation is
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// done.
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ArgumentPurpose::FramePointer |
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ArgumentPurpose::CalleeSaved => {
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panic!("Premature callee-saved arg {}", arg);
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}
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// These can be meaningfully added by `legalize_signature()`.
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ArgumentPurpose::Link => {
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debug_assert!(!has_link, "Multiple link parameters found");
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has_link = true;
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}
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ArgumentPurpose::StructReturn => {
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debug_assert!(!has_sret, "Multiple sret parameters found");
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has_sret = true;
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}
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ArgumentPurpose::VMContext => {
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debug_assert!(!has_vmctx, "Multiple vmctx parameters found");
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has_vmctx = true;
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}
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ArgumentPurpose::SignatureId => {
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debug_assert!(!has_sigid, "Multiple sigid parameters found");
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has_sigid = true;
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}
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}
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// Just create entry block values to match here. We will use them in `handle_return_abi()`
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// below.
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pos.func.dfg.append_ebb_param(entry, arg.value_type);
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}
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}
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/// Legalize the results returned from a call instruction to match the ABI signature.
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///
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/// The cursor `pos` points to a call instruction with at least one return value. The cursor will
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/// be left pointing after the instructions inserted to convert the return values.
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///
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/// This function is very similar to the `legalize_entry_params` function above.
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///
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/// Returns the possibly new instruction representing the call.
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fn legalize_inst_results<ResType>(pos: &mut FuncCursor, mut get_abi_type: ResType) -> Inst
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where
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ResType: FnMut(&Function, usize) -> AbiParam,
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{
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let call = pos.current_inst().expect(
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"Cursor must point to a call instruction",
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);
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// We theoretically allow for call instructions that return a number of fixed results before
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// the call return values. In practice, it doesn't happen.
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let fixed_results = pos.func.dfg[call].opcode().constraints().fixed_results();
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debug_assert_eq!(fixed_results, 0, "Fixed results on calls not supported");
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let results = pos.func.dfg.detach_results(call);
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let mut next_res = 0;
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let mut abi_res = 0;
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// Point immediately after the call.
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pos.next_inst();
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while let Some(res) = results.get(next_res, &pos.func.dfg.value_lists) {
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next_res += 1;
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let res_type = pos.func.dfg.value_type(res);
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if res_type == get_abi_type(pos.func, abi_res).value_type {
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// No value translation is necessary, this result matches the ABI type.
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pos.func.dfg.attach_result(call, res);
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abi_res += 1;
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} else {
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let mut get_res = |func: &mut Function, ty| {
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let abi_type = get_abi_type(func, abi_res);
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if ty == abi_type.value_type {
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let last_res = func.dfg.append_result(call, ty);
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abi_res += 1;
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Ok(last_res)
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} else {
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Err(abi_type)
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}
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};
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let v = convert_from_abi(pos, res_type, Some(res), &mut get_res);
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debug_assert_eq!(pos.func.dfg.resolve_aliases(res), v);
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}
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}
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call
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}
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/// Compute original value of type `ty` from the legalized ABI arguments.
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///
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/// The conversion is recursive, controlled by the `get_arg` closure which is called to retrieve an
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/// ABI argument. It returns:
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///
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/// - `Ok(arg)` if the requested type matches the next ABI argument.
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/// - `Err(arg_type)` if further conversions are needed from the ABI argument `arg_type`.
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///
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/// If the `into_result` value is provided, the converted result will be written into that value.
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fn convert_from_abi<GetArg>(
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pos: &mut FuncCursor,
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ty: Type,
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into_result: Option<Value>,
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get_arg: &mut GetArg,
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) -> Value
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where
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GetArg: FnMut(&mut Function, Type) -> Result<Value, AbiParam>,
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{
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// Terminate the recursion when we get the desired type.
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let arg_type = match get_arg(pos.func, ty) {
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Ok(v) => {
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debug_assert_eq!(pos.func.dfg.value_type(v), ty);
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debug_assert_eq!(into_result, None);
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return v;
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}
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Err(t) => t,
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};
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// Reconstruct how `ty` was legalized into the `arg_type` argument.
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let conversion = legalize_abi_value(ty, &arg_type);
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dbg!("convert_from_abi({}): {:?}", ty, conversion);
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// The conversion describes value to ABI argument. We implement the reverse conversion here.
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match conversion {
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// Construct a `ty` by concatenating two ABI integers.
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ValueConversion::IntSplit => {
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let abi_ty = ty.half_width().expect("Invalid type for conversion");
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let lo = convert_from_abi(pos, abi_ty, None, get_arg);
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let hi = convert_from_abi(pos, abi_ty, None, get_arg);
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dbg!(
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"intsplit {}: {}, {}: {}",
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lo,
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pos.func.dfg.value_type(lo),
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hi,
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pos.func.dfg.value_type(hi)
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);
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pos.ins().with_results([into_result]).iconcat(lo, hi)
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}
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// Construct a `ty` by concatenating two halves of a vector.
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ValueConversion::VectorSplit => {
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let abi_ty = ty.half_vector().expect("Invalid type for conversion");
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let lo = convert_from_abi(pos, abi_ty, None, get_arg);
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let hi = convert_from_abi(pos, abi_ty, None, get_arg);
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pos.ins().with_results([into_result]).vconcat(lo, hi)
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}
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// Construct a `ty` by bit-casting from an integer type.
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ValueConversion::IntBits => {
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debug_assert!(!ty.is_int());
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let abi_ty = Type::int(ty.bits()).expect("Invalid type for conversion");
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let arg = convert_from_abi(pos, abi_ty, None, get_arg);
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pos.ins().with_results([into_result]).bitcast(ty, arg)
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}
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// ABI argument is a sign-extended version of the value we want.
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ValueConversion::Sext(abi_ty) => {
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let arg = convert_from_abi(pos, abi_ty, None, get_arg);
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// TODO: Currently, we don't take advantage of the ABI argument being sign-extended.
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// We could insert an `assert_sreduce` which would fold with a following `sextend` of
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// this value.
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pos.ins().with_results([into_result]).ireduce(ty, arg)
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}
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ValueConversion::Uext(abi_ty) => {
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let arg = convert_from_abi(pos, abi_ty, None, get_arg);
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// TODO: Currently, we don't take advantage of the ABI argument being sign-extended.
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// We could insert an `assert_ureduce` which would fold with a following `uextend` of
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// this value.
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pos.ins().with_results([into_result]).ireduce(ty, arg)
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}
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}
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}
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/// Convert `value` to match an ABI signature by inserting instructions at `pos`.
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///
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/// This may require expanding the value to multiple ABI arguments. The conversion process is
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/// recursive and controlled by the `put_arg` closure. When a candidate argument value is presented
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/// to the closure, it will perform one of two actions:
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///
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/// 1. If the suggested argument has an acceptable value type, consume it by adding it to the list
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/// of arguments and return `Ok(())`.
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/// 2. If the suggested argument doesn't have the right value type, don't change anything, but
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/// return the `Err(AbiParam)` that is needed.
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///
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fn convert_to_abi<PutArg>(
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pos: &mut FuncCursor,
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cfg: &ControlFlowGraph,
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value: Value,
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put_arg: &mut PutArg,
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) where
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PutArg: FnMut(&mut Function, Value) -> Result<(), AbiParam>,
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{
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// Start by invoking the closure to either terminate the recursion or get the argument type
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// we're trying to match.
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let arg_type = match put_arg(pos.func, value) {
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Ok(_) => return,
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Err(t) => t,
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};
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let ty = pos.func.dfg.value_type(value);
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match legalize_abi_value(ty, &arg_type) {
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ValueConversion::IntSplit => {
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let curpos = pos.position();
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let srcloc = pos.srcloc();
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let (lo, hi) = isplit(&mut pos.func, cfg, curpos, srcloc, value);
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convert_to_abi(pos, cfg, lo, put_arg);
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convert_to_abi(pos, cfg, hi, put_arg);
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}
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ValueConversion::VectorSplit => {
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let curpos = pos.position();
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let srcloc = pos.srcloc();
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let (lo, hi) = vsplit(&mut pos.func, cfg, curpos, srcloc, value);
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convert_to_abi(pos, cfg, lo, put_arg);
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convert_to_abi(pos, cfg, hi, put_arg);
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}
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ValueConversion::IntBits => {
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debug_assert!(!ty.is_int());
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let abi_ty = Type::int(ty.bits()).expect("Invalid type for conversion");
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let arg = pos.ins().bitcast(abi_ty, value);
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convert_to_abi(pos, cfg, arg, put_arg);
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}
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ValueConversion::Sext(abi_ty) => {
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let arg = pos.ins().sextend(abi_ty, value);
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convert_to_abi(pos, cfg, arg, put_arg);
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}
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ValueConversion::Uext(abi_ty) => {
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let arg = pos.ins().uextend(abi_ty, value);
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convert_to_abi(pos, cfg, arg, put_arg);
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}
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}
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}
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/// Check if a sequence of arguments match a desired sequence of argument types.
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fn check_arg_types(dfg: &DataFlowGraph, args: &[Value], types: &[AbiParam]) -> bool {
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let arg_types = args.iter().map(|&v| dfg.value_type(v));
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let sig_types = types.iter().map(|&at| at.value_type);
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arg_types.eq(sig_types)
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}
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/// Check if the arguments of the call `inst` match the signature.
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///
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/// Returns `Ok(())` if the signature matches and no changes are needed, or `Err(sig_ref)` if the
|
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/// signature doesn't match.
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fn check_call_signature(dfg: &DataFlowGraph, inst: Inst) -> Result<(), SigRef> {
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// Extract the signature and argument values.
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let (sig_ref, args) = match dfg[inst].analyze_call(&dfg.value_lists) {
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CallInfo::Direct(func, args) => (dfg.ext_funcs[func].signature, args),
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CallInfo::Indirect(sig_ref, args) => (sig_ref, args),
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CallInfo::NotACall => panic!("Expected call, got {:?}", dfg[inst]),
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};
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let sig = &dfg.signatures[sig_ref];
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if check_arg_types(dfg, args, &sig.params[..]) &&
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check_arg_types(dfg, dfg.inst_results(inst), &sig.returns[..])
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{
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// All types check out.
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Ok(())
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} else {
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// Call types need fixing.
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Err(sig_ref)
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}
|
||||
}
|
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|
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/// Check if the arguments of the return `inst` match the signature.
|
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fn check_return_signature(dfg: &DataFlowGraph, inst: Inst, sig: &Signature) -> bool {
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check_arg_types(dfg, dfg.inst_variable_args(inst), &sig.returns)
|
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}
|
||||
|
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/// Insert ABI conversion code for the arguments to the call or return instruction at `pos`.
|
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///
|
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/// - `abi_args` is the number of arguments that the ABI signature requires.
|
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/// - `get_abi_type` is a closure that can provide the desired `AbiParam` for a given ABI
|
||||
/// argument number in `0..abi_args`.
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///
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fn legalize_inst_arguments<ArgType>(
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pos: &mut FuncCursor,
|
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cfg: &ControlFlowGraph,
|
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abi_args: usize,
|
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mut get_abi_type: ArgType,
|
||||
) where
|
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ArgType: FnMut(&Function, usize) -> AbiParam,
|
||||
{
|
||||
let inst = pos.current_inst().expect(
|
||||
"Cursor must point to a call instruction",
|
||||
);
|
||||
|
||||
// Lift the value list out of the call instruction so we modify it.
|
||||
let mut vlist = pos.func.dfg[inst].take_value_list().expect(
|
||||
"Call must have a value list",
|
||||
);
|
||||
|
||||
// The value list contains all arguments to the instruction, including the callee on an
|
||||
// indirect call which isn't part of the call arguments that must match the ABI signature.
|
||||
// Figure out how many fixed values are at the front of the list. We won't touch those.
|
||||
let fixed_values = pos.func.dfg[inst]
|
||||
.opcode()
|
||||
.constraints()
|
||||
.fixed_value_arguments();
|
||||
let have_args = vlist.len(&pos.func.dfg.value_lists) - fixed_values;
|
||||
|
||||
// Grow the value list to the right size and shift all the existing arguments to the right.
|
||||
// This lets us write the new argument values into the list without overwriting the old
|
||||
// arguments.
|
||||
//
|
||||
// Before:
|
||||
//
|
||||
// <--> fixed_values
|
||||
// <-----------> have_args
|
||||
// [FFFFOOOOOOOOOOOOO]
|
||||
//
|
||||
// After grow_at():
|
||||
//
|
||||
// <--> fixed_values
|
||||
// <-----------> have_args
|
||||
// <------------------> abi_args
|
||||
// [FFFF-------OOOOOOOOOOOOO]
|
||||
// ^
|
||||
// old_arg_offset
|
||||
//
|
||||
// After writing the new arguments:
|
||||
//
|
||||
// <--> fixed_values
|
||||
// <------------------> abi_args
|
||||
// [FFFFNNNNNNNNNNNNNNNNNNNN]
|
||||
//
|
||||
vlist.grow_at(
|
||||
fixed_values,
|
||||
abi_args - have_args,
|
||||
&mut pos.func.dfg.value_lists,
|
||||
);
|
||||
let old_arg_offset = fixed_values + abi_args - have_args;
|
||||
|
||||
let mut abi_arg = 0;
|
||||
for old_arg in 0..have_args {
|
||||
let old_value = vlist
|
||||
.get(old_arg_offset + old_arg, &pos.func.dfg.value_lists)
|
||||
.unwrap();
|
||||
let mut put_arg = |func: &mut Function, arg| {
|
||||
let abi_type = get_abi_type(func, abi_arg);
|
||||
if func.dfg.value_type(arg) == abi_type.value_type {
|
||||
// This is the argument type we need.
|
||||
vlist.as_mut_slice(&mut func.dfg.value_lists)[fixed_values + abi_arg] = arg;
|
||||
abi_arg += 1;
|
||||
Ok(())
|
||||
} else {
|
||||
Err(abi_type)
|
||||
}
|
||||
};
|
||||
convert_to_abi(pos, cfg, old_value, &mut put_arg);
|
||||
}
|
||||
|
||||
// Put the modified value list back.
|
||||
pos.func.dfg[inst].put_value_list(vlist);
|
||||
}
|
||||
|
||||
/// Insert ABI conversion code before and after the call instruction at `pos`.
|
||||
///
|
||||
/// Instructions inserted before the call will compute the appropriate ABI values for the
|
||||
/// callee's new ABI-legalized signature. The function call arguments are rewritten in place to
|
||||
/// match the new signature.
|
||||
///
|
||||
/// Instructions will be inserted after the call to convert returned ABI values back to the
|
||||
/// original return values. The call's result values will be adapted to match the new signature.
|
||||
///
|
||||
/// Returns `true` if any instructions were inserted.
|
||||
pub fn handle_call_abi(mut inst: Inst, func: &mut Function, cfg: &ControlFlowGraph) -> bool {
|
||||
let pos = &mut FuncCursor::new(func).at_inst(inst);
|
||||
pos.use_srcloc(inst);
|
||||
|
||||
// Start by checking if the argument types already match the signature.
|
||||
let sig_ref = match check_call_signature(&pos.func.dfg, inst) {
|
||||
Ok(_) => return spill_call_arguments(pos),
|
||||
Err(s) => s,
|
||||
};
|
||||
|
||||
// OK, we need to fix the call arguments to match the ABI signature.
|
||||
let abi_args = pos.func.dfg.signatures[sig_ref].params.len();
|
||||
legalize_inst_arguments(pos, cfg, abi_args, |func, abi_arg| {
|
||||
func.dfg.signatures[sig_ref].params[abi_arg]
|
||||
});
|
||||
|
||||
if !pos.func.dfg.signatures[sig_ref].returns.is_empty() {
|
||||
inst = legalize_inst_results(pos, |func, abi_res| {
|
||||
func.dfg.signatures[sig_ref].returns[abi_res]
|
||||
});
|
||||
}
|
||||
|
||||
debug_assert!(
|
||||
check_call_signature(&pos.func.dfg, inst).is_ok(),
|
||||
"Signature still wrong: {}, {}{}",
|
||||
pos.func.dfg.display_inst(inst, None),
|
||||
sig_ref,
|
||||
pos.func.dfg.signatures[sig_ref]
|
||||
);
|
||||
|
||||
// Go back and insert spills for any stack arguments.
|
||||
pos.goto_inst(inst);
|
||||
spill_call_arguments(pos);
|
||||
|
||||
// Yes, we changed stuff.
|
||||
true
|
||||
}
|
||||
|
||||
/// Insert ABI conversion code before and after the return instruction at `inst`.
|
||||
///
|
||||
/// Return `true` if any instructions were inserted.
|
||||
pub fn handle_return_abi(inst: Inst, func: &mut Function, cfg: &ControlFlowGraph) -> bool {
|
||||
// Check if the returned types already match the signature.
|
||||
if check_return_signature(&func.dfg, inst, &func.signature) {
|
||||
return false;
|
||||
}
|
||||
|
||||
// Count the special-purpose return values (`link`, `sret`, and `vmctx`) that were appended to
|
||||
// the legalized signature.
|
||||
let special_args = func.signature
|
||||
.returns
|
||||
.iter()
|
||||
.rev()
|
||||
.take_while(|&rt| {
|
||||
rt.purpose == ArgumentPurpose::Link || rt.purpose == ArgumentPurpose::StructReturn ||
|
||||
rt.purpose == ArgumentPurpose::VMContext
|
||||
})
|
||||
.count();
|
||||
let abi_args = func.signature.returns.len() - special_args;
|
||||
|
||||
let pos = &mut FuncCursor::new(func).at_inst(inst);
|
||||
pos.use_srcloc(inst);
|
||||
|
||||
legalize_inst_arguments(pos, cfg, abi_args, |func, abi_arg| {
|
||||
func.signature.returns[abi_arg]
|
||||
});
|
||||
debug_assert_eq!(pos.func.dfg.inst_variable_args(inst).len(), abi_args);
|
||||
|
||||
// Append special return arguments for any `sret`, `link`, and `vmctx` return values added to
|
||||
// the legalized signature. These values should simply be propagated from the entry block
|
||||
// arguments.
|
||||
if special_args > 0 {
|
||||
dbg!(
|
||||
"Adding {} special-purpose arguments to {}",
|
||||
special_args,
|
||||
pos.func.dfg.display_inst(inst, None)
|
||||
);
|
||||
let mut vlist = pos.func.dfg[inst].take_value_list().unwrap();
|
||||
for arg in &pos.func.signature.returns[abi_args..] {
|
||||
match arg.purpose {
|
||||
ArgumentPurpose::Link |
|
||||
ArgumentPurpose::StructReturn |
|
||||
ArgumentPurpose::VMContext => {}
|
||||
ArgumentPurpose::Normal => panic!("unexpected return value {}", arg),
|
||||
_ => panic!("Unsupported special purpose return value {}", arg),
|
||||
}
|
||||
// A `link`/`sret`/`vmctx` return value can only appear in a signature that has a
|
||||
// unique matching argument. They are appended at the end, so search the signature from
|
||||
// the end.
|
||||
let idx = pos.func
|
||||
.signature
|
||||
.params
|
||||
.iter()
|
||||
.rposition(|t| t.purpose == arg.purpose)
|
||||
.expect("No matching special purpose argument.");
|
||||
// Get the corresponding entry block value and add it to the return instruction's
|
||||
// arguments.
|
||||
let val = pos.func.dfg.ebb_params(
|
||||
pos.func.layout.entry_block().unwrap(),
|
||||
)
|
||||
[idx];
|
||||
debug_assert_eq!(pos.func.dfg.value_type(val), arg.value_type);
|
||||
vlist.push(val, &mut pos.func.dfg.value_lists);
|
||||
}
|
||||
pos.func.dfg[inst].put_value_list(vlist);
|
||||
}
|
||||
|
||||
debug_assert!(
|
||||
check_return_signature(&pos.func.dfg, inst, &pos.func.signature),
|
||||
"Signature still wrong: {} / signature {}",
|
||||
pos.func.dfg.display_inst(inst, None),
|
||||
pos.func.signature
|
||||
);
|
||||
|
||||
// Yes, we changed stuff.
|
||||
true
|
||||
}
|
||||
|
||||
/// Assign stack slots to incoming function parameters on the stack.
|
||||
///
|
||||
/// Values that are passed into the function on the stack must be assigned to an `IncomingArg`
|
||||
/// stack slot already during legalization.
|
||||
fn spill_entry_params(func: &mut Function, entry: Ebb) {
|
||||
for (abi, &arg) in func.signature.params.iter().zip(func.dfg.ebb_params(entry)) {
|
||||
if let ArgumentLoc::Stack(offset) = abi.location {
|
||||
let ss = func.stack_slots.make_incoming_arg(abi.value_type, offset);
|
||||
func.locations[arg] = ValueLoc::Stack(ss);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Assign stack slots to outgoing function arguments on the stack.
|
||||
///
|
||||
/// Values that are passed to a called function on the stack must be assigned to a matching
|
||||
/// `OutgoingArg` stack slot. The assignment must happen immediately before the call.
|
||||
///
|
||||
/// TODO: The outgoing stack slots can be written a bit earlier, as long as there are no branches
|
||||
/// or calls between writing the stack slots and the call instruction. Writing the slots earlier
|
||||
/// could help reduce register pressure before the call.
|
||||
fn spill_call_arguments(pos: &mut FuncCursor) -> bool {
|
||||
let inst = pos.current_inst().expect(
|
||||
"Cursor must point to a call instruction",
|
||||
);
|
||||
let sig_ref = pos.func.dfg.call_signature(inst).expect(
|
||||
"Call instruction expected.",
|
||||
);
|
||||
|
||||
// Start by building a list of stack slots and arguments to be replaced.
|
||||
// This requires borrowing `pos.func.dfg`, so we can't change anything.
|
||||
let arglist = {
|
||||
let locations = &pos.func.locations;
|
||||
let stack_slots = &mut pos.func.stack_slots;
|
||||
pos.func
|
||||
.dfg
|
||||
.inst_variable_args(inst)
|
||||
.iter()
|
||||
.zip(&pos.func.dfg.signatures[sig_ref].params)
|
||||
.enumerate()
|
||||
.filter_map(|(idx, (&arg, abi))| {
|
||||
match abi.location {
|
||||
ArgumentLoc::Stack(offset) => {
|
||||
// Assign `arg` to a new stack slot, unless it's already in the correct
|
||||
// slot. The legalization needs to be idempotent, so we should see a
|
||||
// correct outgoing slot on the second pass.
|
||||
let ss = stack_slots.get_outgoing_arg(abi.value_type, offset);
|
||||
if locations[arg] != ValueLoc::Stack(ss) {
|
||||
Some((idx, arg, ss))
|
||||
} else {
|
||||
None
|
||||
}
|
||||
}
|
||||
_ => None,
|
||||
}
|
||||
})
|
||||
.collect::<Vec<_>>()
|
||||
};
|
||||
|
||||
if arglist.is_empty() {
|
||||
return false;
|
||||
}
|
||||
|
||||
// Insert the spill instructions and rewrite call arguments.
|
||||
for (idx, arg, ss) in arglist {
|
||||
let stack_val = pos.ins().spill(arg);
|
||||
pos.func.locations[stack_val] = ValueLoc::Stack(ss);
|
||||
pos.func.dfg.inst_variable_args_mut(inst)[idx] = stack_val;
|
||||
}
|
||||
|
||||
// We changed stuff.
|
||||
true
|
||||
}
|
||||
Reference in New Issue
Block a user