moved crates in lib/ to src/, renamed crates, modified some files' text (#660)
moved crates in lib/ to src/, renamed crates, modified some files' text (#660)
This commit is contained in:
lazypassion
579
cranelift/codegen/src/isa/x86/abi.rs
Normal file
579
cranelift/codegen/src/isa/x86/abi.rs
Normal file
@@ -0,0 +1,579 @@
|
||||
//! x86 ABI implementation.
|
||||
|
||||
use super::registers::{FPR, GPR, RU};
|
||||
use crate::abi::{legalize_args, ArgAction, ArgAssigner, ValueConversion};
|
||||
use crate::cursor::{Cursor, CursorPosition, EncCursor};
|
||||
use crate::ir;
|
||||
use crate::ir::immediates::Imm64;
|
||||
use crate::ir::stackslot::{StackOffset, StackSize};
|
||||
use crate::ir::{
|
||||
get_probestack_funcref, AbiParam, ArgumentExtension, ArgumentLoc, ArgumentPurpose, InstBuilder,
|
||||
ValueLoc,
|
||||
};
|
||||
use crate::isa::{CallConv, RegClass, RegUnit, TargetIsa};
|
||||
use crate::regalloc::RegisterSet;
|
||||
use crate::result::CodegenResult;
|
||||
use crate::stack_layout::layout_stack;
|
||||
use core::i32;
|
||||
use target_lexicon::{PointerWidth, Triple};
|
||||
|
||||
/// Argument registers for x86-64
|
||||
static ARG_GPRS: [RU; 6] = [RU::rdi, RU::rsi, RU::rdx, RU::rcx, RU::r8, RU::r9];
|
||||
|
||||
/// Return value registers.
|
||||
static RET_GPRS: [RU; 3] = [RU::rax, RU::rdx, RU::rcx];
|
||||
|
||||
/// Argument registers for x86-64, when using windows fastcall
|
||||
static ARG_GPRS_WIN_FASTCALL_X64: [RU; 4] = [RU::rcx, RU::rdx, RU::r8, RU::r9];
|
||||
|
||||
/// Return value registers for x86-64, when using windows fastcall
|
||||
static RET_GPRS_WIN_FASTCALL_X64: [RU; 1] = [RU::rax];
|
||||
|
||||
struct Args {
|
||||
pointer_bytes: u8,
|
||||
pointer_bits: u8,
|
||||
pointer_type: ir::Type,
|
||||
gpr: &'static [RU],
|
||||
gpr_used: usize,
|
||||
fpr_limit: usize,
|
||||
fpr_used: usize,
|
||||
offset: u32,
|
||||
call_conv: CallConv,
|
||||
}
|
||||
|
||||
impl Args {
|
||||
fn new(bits: u8, gpr: &'static [RU], fpr_limit: usize, call_conv: CallConv) -> Self {
|
||||
let offset = if let CallConv::WindowsFastcall = call_conv {
|
||||
// [1] "The caller is responsible for allocating space for parameters to the callee,
|
||||
// and must always allocate sufficient space to store four register parameters"
|
||||
32
|
||||
} else {
|
||||
0
|
||||
};
|
||||
|
||||
Self {
|
||||
pointer_bytes: bits / 8,
|
||||
pointer_bits: bits,
|
||||
pointer_type: ir::Type::int(u16::from(bits)).unwrap(),
|
||||
gpr,
|
||||
gpr_used: 0,
|
||||
fpr_limit,
|
||||
fpr_used: 0,
|
||||
offset,
|
||||
call_conv,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
impl ArgAssigner for Args {
|
||||
fn assign(&mut self, arg: &AbiParam) -> ArgAction {
|
||||
let ty = arg.value_type;
|
||||
|
||||
// Check for a legal type.
|
||||
// We don't support SIMD yet, so break all vectors down.
|
||||
if ty.is_vector() {
|
||||
return ValueConversion::VectorSplit.into();
|
||||
}
|
||||
|
||||
// Large integers and booleans are broken down to fit in a register.
|
||||
if !ty.is_float() && ty.bits() > u16::from(self.pointer_bits) {
|
||||
return ValueConversion::IntSplit.into();
|
||||
}
|
||||
|
||||
// Small integers are extended to the size of a pointer register.
|
||||
if ty.is_int() && ty.bits() < u16::from(self.pointer_bits) {
|
||||
match arg.extension {
|
||||
ArgumentExtension::None => {}
|
||||
ArgumentExtension::Uext => return ValueConversion::Uext(self.pointer_type).into(),
|
||||
ArgumentExtension::Sext => return ValueConversion::Sext(self.pointer_type).into(),
|
||||
}
|
||||
}
|
||||
|
||||
// Handle special-purpose arguments.
|
||||
if ty.is_int() && self.call_conv == CallConv::Baldrdash {
|
||||
match arg.purpose {
|
||||
// This is SpiderMonkey's `WasmTlsReg`.
|
||||
ArgumentPurpose::VMContext => {
|
||||
return ArgumentLoc::Reg(if self.pointer_bits == 64 {
|
||||
RU::r14
|
||||
} else {
|
||||
RU::rsi
|
||||
} as RegUnit)
|
||||
.into();
|
||||
}
|
||||
// This is SpiderMonkey's `WasmTableCallSigReg`.
|
||||
ArgumentPurpose::SignatureId => return ArgumentLoc::Reg(RU::r10 as RegUnit).into(),
|
||||
_ => {}
|
||||
}
|
||||
}
|
||||
|
||||
// Try to use a GPR.
|
||||
if !ty.is_float() && self.gpr_used < self.gpr.len() {
|
||||
let reg = self.gpr[self.gpr_used] as RegUnit;
|
||||
self.gpr_used += 1;
|
||||
return ArgumentLoc::Reg(reg).into();
|
||||
}
|
||||
|
||||
// Try to use an FPR.
|
||||
if ty.is_float() && self.fpr_used < self.fpr_limit {
|
||||
let reg = FPR.unit(self.fpr_used);
|
||||
self.fpr_used += 1;
|
||||
return ArgumentLoc::Reg(reg).into();
|
||||
}
|
||||
|
||||
// Assign a stack location.
|
||||
let loc = ArgumentLoc::Stack(self.offset as i32);
|
||||
self.offset += u32::from(self.pointer_bytes);
|
||||
debug_assert!(self.offset <= i32::MAX as u32);
|
||||
loc.into()
|
||||
}
|
||||
}
|
||||
|
||||
/// Legalize `sig`.
|
||||
pub fn legalize_signature(sig: &mut ir::Signature, triple: &Triple, _current: bool) {
|
||||
let bits;
|
||||
let mut args;
|
||||
|
||||
match triple.pointer_width().unwrap() {
|
||||
PointerWidth::U16 => panic!(),
|
||||
PointerWidth::U32 => {
|
||||
bits = 32;
|
||||
args = Args::new(bits, &[], 0, sig.call_conv);
|
||||
}
|
||||
PointerWidth::U64 => {
|
||||
bits = 64;
|
||||
args = if sig.call_conv == CallConv::WindowsFastcall {
|
||||
Args::new(bits, &ARG_GPRS_WIN_FASTCALL_X64[..], 4, sig.call_conv)
|
||||
} else {
|
||||
Args::new(bits, &ARG_GPRS[..], 8, sig.call_conv)
|
||||
};
|
||||
}
|
||||
}
|
||||
|
||||
legalize_args(&mut sig.params, &mut args);
|
||||
|
||||
let regs = if sig.call_conv == CallConv::WindowsFastcall {
|
||||
&RET_GPRS_WIN_FASTCALL_X64[..]
|
||||
} else {
|
||||
&RET_GPRS[..]
|
||||
};
|
||||
|
||||
let mut rets = Args::new(bits, regs, 2, sig.call_conv);
|
||||
legalize_args(&mut sig.returns, &mut rets);
|
||||
}
|
||||
|
||||
/// Get register class for a type appearing in a legalized signature.
|
||||
pub fn regclass_for_abi_type(ty: ir::Type) -> RegClass {
|
||||
if ty.is_int() || ty.is_bool() {
|
||||
GPR
|
||||
} else {
|
||||
FPR
|
||||
}
|
||||
}
|
||||
|
||||
/// Get the set of allocatable registers for `func`.
|
||||
pub fn allocatable_registers(_func: &ir::Function, triple: &Triple) -> RegisterSet {
|
||||
let mut regs = RegisterSet::new();
|
||||
regs.take(GPR, RU::rsp as RegUnit);
|
||||
regs.take(GPR, RU::rbp as RegUnit);
|
||||
|
||||
// 32-bit arch only has 8 registers.
|
||||
if triple.pointer_width().unwrap() != PointerWidth::U64 {
|
||||
for i in 8..16 {
|
||||
regs.take(GPR, GPR.unit(i));
|
||||
regs.take(FPR, FPR.unit(i));
|
||||
}
|
||||
}
|
||||
|
||||
regs
|
||||
}
|
||||
|
||||
/// Get the set of callee-saved registers.
|
||||
fn callee_saved_gprs(isa: &TargetIsa, call_conv: CallConv) -> &'static [RU] {
|
||||
match isa.triple().pointer_width().unwrap() {
|
||||
PointerWidth::U16 => panic!(),
|
||||
PointerWidth::U32 => &[RU::rbx, RU::rsi, RU::rdi],
|
||||
PointerWidth::U64 => {
|
||||
if call_conv == CallConv::WindowsFastcall {
|
||||
// "registers RBX, RBP, RDI, RSI, RSP, R12, R13, R14, R15 are considered nonvolatile
|
||||
// and must be saved and restored by a function that uses them."
|
||||
// as per https://msdn.microsoft.com/en-us/library/6t169e9c.aspx
|
||||
// RSP & RSB are not listed below, since they are restored automatically during
|
||||
// a function call. If that wasn't the case, function calls (RET) would not work.
|
||||
&[
|
||||
RU::rbx,
|
||||
RU::rdi,
|
||||
RU::rsi,
|
||||
RU::r12,
|
||||
RU::r13,
|
||||
RU::r14,
|
||||
RU::r15,
|
||||
]
|
||||
} else {
|
||||
&[RU::rbx, RU::r12, RU::r13, RU::r14, RU::r15]
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Get the set of callee-saved registers that are used.
|
||||
fn callee_saved_gprs_used(isa: &TargetIsa, func: &ir::Function) -> RegisterSet {
|
||||
let mut all_callee_saved = RegisterSet::empty();
|
||||
for reg in callee_saved_gprs(isa, func.signature.call_conv) {
|
||||
all_callee_saved.free(GPR, *reg as RegUnit);
|
||||
}
|
||||
|
||||
let mut used = RegisterSet::empty();
|
||||
for value_loc in func.locations.values() {
|
||||
// Note that `value_loc` here contains only a single unit of a potentially multi-unit
|
||||
// register. We don't use registers that overlap each other in the x86 ISA, but in others
|
||||
// we do. So this should not be blindly reused.
|
||||
if let ValueLoc::Reg(ru) = *value_loc {
|
||||
if !used.is_avail(GPR, ru) {
|
||||
used.free(GPR, ru);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// regmove and regfill instructions may temporarily divert values into other registers,
|
||||
// and these are not reflected in `func.locations`. Scan the function for such instructions
|
||||
// and note which callee-saved registers they use.
|
||||
//
|
||||
// TODO: Consider re-evaluating how regmove/regfill/regspill work and whether it's possible
|
||||
// to avoid this step.
|
||||
for ebb in &func.layout {
|
||||
for inst in func.layout.ebb_insts(ebb) {
|
||||
match func.dfg[inst] {
|
||||
ir::instructions::InstructionData::RegMove { dst, .. }
|
||||
| ir::instructions::InstructionData::RegFill { dst, .. } => {
|
||||
if !used.is_avail(GPR, dst) {
|
||||
used.free(GPR, dst);
|
||||
}
|
||||
}
|
||||
_ => (),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
used.intersect(&all_callee_saved);
|
||||
used
|
||||
}
|
||||
|
||||
pub fn prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> CodegenResult<()> {
|
||||
match func.signature.call_conv {
|
||||
// For now, just translate fast and cold as system_v.
|
||||
CallConv::Fast | CallConv::Cold | CallConv::SystemV => {
|
||||
system_v_prologue_epilogue(func, isa)
|
||||
}
|
||||
CallConv::WindowsFastcall => fastcall_prologue_epilogue(func, isa),
|
||||
CallConv::Baldrdash => baldrdash_prologue_epilogue(func, isa),
|
||||
CallConv::Probestack => unimplemented!("probestack calling convention"),
|
||||
}
|
||||
}
|
||||
|
||||
fn baldrdash_prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> CodegenResult<()> {
|
||||
debug_assert!(
|
||||
!isa.flags().probestack_enabled(),
|
||||
"baldrdash does not expect cranelift to emit stack probes"
|
||||
);
|
||||
|
||||
// Baldrdash on 32-bit x86 always aligns its stack pointer to 16 bytes.
|
||||
let stack_align = 16;
|
||||
let word_size = StackSize::from(isa.pointer_bytes());
|
||||
let bytes = StackSize::from(isa.flags().baldrdash_prologue_words()) * word_size;
|
||||
|
||||
let mut ss = ir::StackSlotData::new(ir::StackSlotKind::IncomingArg, bytes);
|
||||
ss.offset = Some(-(bytes as StackOffset));
|
||||
func.stack_slots.push(ss);
|
||||
|
||||
layout_stack(&mut func.stack_slots, stack_align)?;
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Implementation of the fastcall-based Win64 calling convention described at [1]
|
||||
/// [1] https://msdn.microsoft.com/en-us/library/ms235286.aspx
|
||||
fn fastcall_prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> CodegenResult<()> {
|
||||
if isa.triple().pointer_width().unwrap() != PointerWidth::U64 {
|
||||
panic!("TODO: windows-fastcall: x86-32 not implemented yet");
|
||||
}
|
||||
|
||||
// [1] "The primary exceptions are the stack pointer and malloc or alloca memory,
|
||||
// which are aligned to 16 bytes in order to aid performance"
|
||||
let stack_align = 16;
|
||||
|
||||
let word_size = isa.pointer_bytes() as usize;
|
||||
let reg_type = isa.pointer_type();
|
||||
|
||||
let csrs = callee_saved_gprs_used(isa, func);
|
||||
|
||||
// [1] "Space is allocated on the call stack as a shadow store for callees to save"
|
||||
// This shadow store contains the parameters which are passed through registers (ARG_GPRS)
|
||||
// and is eventually used by the callee to save & restore the values of the arguments.
|
||||
//
|
||||
// [2] https://blogs.msdn.microsoft.com/oldnewthing/20110302-00/?p=11333
|
||||
// "Although the x64 calling convention reserves spill space for parameters,
|
||||
// you don’t have to use them as such"
|
||||
//
|
||||
// The reserved stack area is composed of:
|
||||
// return address + frame pointer + all callee-saved registers + shadow space
|
||||
//
|
||||
// Pushing the return address is an implicit function of the `call`
|
||||
// instruction. Each of the others we will then push explicitly. Then we
|
||||
// will adjust the stack pointer to make room for the rest of the required
|
||||
// space for this frame.
|
||||
const SHADOW_STORE_SIZE: i32 = 32;
|
||||
let csr_stack_size = ((csrs.iter(GPR).len() + 2) * word_size) as i32;
|
||||
|
||||
// TODO: eventually use the 32 bytes (shadow store) as spill slot. This currently doesn't work
|
||||
// since cranelift does not support spill slots before incoming args
|
||||
|
||||
func.create_stack_slot(ir::StackSlotData {
|
||||
kind: ir::StackSlotKind::IncomingArg,
|
||||
size: csr_stack_size as u32,
|
||||
offset: Some(-(SHADOW_STORE_SIZE + csr_stack_size)),
|
||||
});
|
||||
|
||||
let total_stack_size = layout_stack(&mut func.stack_slots, stack_align)? as i32;
|
||||
let local_stack_size = i64::from(total_stack_size - csr_stack_size);
|
||||
|
||||
// Add CSRs to function signature
|
||||
let fp_arg = ir::AbiParam::special_reg(
|
||||
reg_type,
|
||||
ir::ArgumentPurpose::FramePointer,
|
||||
RU::rbp as RegUnit,
|
||||
);
|
||||
func.signature.params.push(fp_arg);
|
||||
func.signature.returns.push(fp_arg);
|
||||
|
||||
for csr in csrs.iter(GPR) {
|
||||
let csr_arg = ir::AbiParam::special_reg(reg_type, ir::ArgumentPurpose::CalleeSaved, csr);
|
||||
func.signature.params.push(csr_arg);
|
||||
func.signature.returns.push(csr_arg);
|
||||
}
|
||||
|
||||
// Set up the cursor and insert the prologue
|
||||
let entry_ebb = func.layout.entry_block().expect("missing entry block");
|
||||
let mut pos = EncCursor::new(func, isa).at_first_insertion_point(entry_ebb);
|
||||
insert_common_prologue(&mut pos, local_stack_size, reg_type, &csrs, isa);
|
||||
|
||||
// Reset the cursor and insert the epilogue
|
||||
let mut pos = pos.at_position(CursorPosition::Nowhere);
|
||||
insert_common_epilogues(&mut pos, local_stack_size, reg_type, &csrs);
|
||||
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Insert a System V-compatible prologue and epilogue.
|
||||
fn system_v_prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> CodegenResult<()> {
|
||||
// The original 32-bit x86 ELF ABI had a 4-byte aligned stack pointer, but
|
||||
// newer versions use a 16-byte aligned stack pointer.
|
||||
let stack_align = 16;
|
||||
let pointer_width = isa.triple().pointer_width().unwrap();
|
||||
let word_size = pointer_width.bytes() as usize;
|
||||
let reg_type = ir::Type::int(u16::from(pointer_width.bits())).unwrap();
|
||||
|
||||
let csrs = callee_saved_gprs_used(isa, func);
|
||||
|
||||
// The reserved stack area is composed of:
|
||||
// return address + frame pointer + all callee-saved registers
|
||||
//
|
||||
// Pushing the return address is an implicit function of the `call`
|
||||
// instruction. Each of the others we will then push explicitly. Then we
|
||||
// will adjust the stack pointer to make room for the rest of the required
|
||||
// space for this frame.
|
||||
let csr_stack_size = ((csrs.iter(GPR).len() + 2) * word_size) as i32;
|
||||
func.create_stack_slot(ir::StackSlotData {
|
||||
kind: ir::StackSlotKind::IncomingArg,
|
||||
size: csr_stack_size as u32,
|
||||
offset: Some(-csr_stack_size),
|
||||
});
|
||||
|
||||
let total_stack_size = layout_stack(&mut func.stack_slots, stack_align)? as i32;
|
||||
let local_stack_size = i64::from(total_stack_size - csr_stack_size);
|
||||
|
||||
// Add CSRs to function signature
|
||||
let fp_arg = ir::AbiParam::special_reg(
|
||||
reg_type,
|
||||
ir::ArgumentPurpose::FramePointer,
|
||||
RU::rbp as RegUnit,
|
||||
);
|
||||
func.signature.params.push(fp_arg);
|
||||
func.signature.returns.push(fp_arg);
|
||||
|
||||
for csr in csrs.iter(GPR) {
|
||||
let csr_arg = ir::AbiParam::special_reg(reg_type, ir::ArgumentPurpose::CalleeSaved, csr);
|
||||
func.signature.params.push(csr_arg);
|
||||
func.signature.returns.push(csr_arg);
|
||||
}
|
||||
|
||||
// Set up the cursor and insert the prologue
|
||||
let entry_ebb = func.layout.entry_block().expect("missing entry block");
|
||||
let mut pos = EncCursor::new(func, isa).at_first_insertion_point(entry_ebb);
|
||||
insert_common_prologue(&mut pos, local_stack_size, reg_type, &csrs, isa);
|
||||
|
||||
// Reset the cursor and insert the epilogue
|
||||
let mut pos = pos.at_position(CursorPosition::Nowhere);
|
||||
insert_common_epilogues(&mut pos, local_stack_size, reg_type, &csrs);
|
||||
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Insert the prologue for a given function.
|
||||
/// This is used by common calling conventions such as System V.
|
||||
fn insert_common_prologue(
|
||||
pos: &mut EncCursor,
|
||||
stack_size: i64,
|
||||
reg_type: ir::types::Type,
|
||||
csrs: &RegisterSet,
|
||||
isa: &TargetIsa,
|
||||
) {
|
||||
if stack_size > 0 {
|
||||
// Check if there is a special stack limit parameter. If so insert stack check.
|
||||
if let Some(stack_limit_arg) = pos.func.special_param(ArgumentPurpose::StackLimit) {
|
||||
// Total stack size is the size of all stack area used by the function, including
|
||||
// pushed CSRs, frame pointer.
|
||||
// Also, the size of a return address, implicitly pushed by a x86 `call` instruction,
|
||||
// also should be accounted for.
|
||||
// TODO: Check if the function body actually contains a `call` instruction.
|
||||
let word_size = isa.pointer_bytes();
|
||||
let total_stack_size = (csrs.iter(GPR).len() + 1 + 1) as i64 * word_size as i64;
|
||||
|
||||
insert_stack_check(pos, total_stack_size, stack_limit_arg);
|
||||
}
|
||||
}
|
||||
|
||||
// Append param to entry EBB
|
||||
let ebb = pos.current_ebb().expect("missing ebb under cursor");
|
||||
let fp = pos.func.dfg.append_ebb_param(ebb, reg_type);
|
||||
pos.func.locations[fp] = ir::ValueLoc::Reg(RU::rbp as RegUnit);
|
||||
|
||||
pos.ins().x86_push(fp);
|
||||
pos.ins()
|
||||
.copy_special(RU::rsp as RegUnit, RU::rbp as RegUnit);
|
||||
|
||||
for reg in csrs.iter(GPR) {
|
||||
// Append param to entry EBB
|
||||
let csr_arg = pos.func.dfg.append_ebb_param(ebb, reg_type);
|
||||
|
||||
// Assign it a location
|
||||
pos.func.locations[csr_arg] = ir::ValueLoc::Reg(reg);
|
||||
|
||||
// Remember it so we can push it momentarily
|
||||
pos.ins().x86_push(csr_arg);
|
||||
}
|
||||
|
||||
// Allocate stack frame storage.
|
||||
if stack_size > 0 {
|
||||
if isa.flags().probestack_enabled()
|
||||
&& stack_size > (1 << isa.flags().probestack_size_log2())
|
||||
{
|
||||
// Emit a stack probe.
|
||||
let rax = RU::rax as RegUnit;
|
||||
let rax_val = ir::ValueLoc::Reg(rax);
|
||||
|
||||
// The probestack function expects its input in %rax.
|
||||
let arg = pos.ins().iconst(reg_type, stack_size);
|
||||
pos.func.locations[arg] = rax_val;
|
||||
|
||||
// Call the probestack function.
|
||||
let callee = get_probestack_funcref(pos.func, reg_type, rax, isa);
|
||||
|
||||
// Make the call.
|
||||
let call = if !isa.flags().is_pic()
|
||||
&& isa.triple().pointer_width().unwrap() == PointerWidth::U64
|
||||
&& !pos.func.dfg.ext_funcs[callee].colocated
|
||||
{
|
||||
// 64-bit non-PIC non-colocated calls need to be legalized to call_indirect.
|
||||
// Use r11 as it may be clobbered under all supported calling conventions.
|
||||
let r11 = RU::r11 as RegUnit;
|
||||
let sig = pos.func.dfg.ext_funcs[callee].signature;
|
||||
let addr = pos.ins().func_addr(reg_type, callee);
|
||||
pos.func.locations[addr] = ir::ValueLoc::Reg(r11);
|
||||
pos.ins().call_indirect(sig, addr, &[arg])
|
||||
} else {
|
||||
// Otherwise just do a normal call.
|
||||
pos.ins().call(callee, &[arg])
|
||||
};
|
||||
|
||||
// If the probestack function doesn't adjust sp, do it ourselves.
|
||||
if !isa.flags().probestack_func_adjusts_sp() {
|
||||
let result = pos.func.dfg.inst_results(call)[0];
|
||||
pos.func.locations[result] = rax_val;
|
||||
pos.ins().adjust_sp_down(result);
|
||||
}
|
||||
} else {
|
||||
// Simply decrement the stack pointer.
|
||||
pos.ins().adjust_sp_down_imm(Imm64::new(stack_size));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Insert a check that generates a trap if the stack pointer goes
|
||||
/// below a value in `stack_limit_arg`.
|
||||
fn insert_stack_check(pos: &mut EncCursor, stack_size: i64, stack_limit_arg: ir::Value) {
|
||||
use crate::ir::condcodes::IntCC;
|
||||
|
||||
// Copy `stack_limit_arg` into a %rax and use it for calculating
|
||||
// a SP threshold.
|
||||
let stack_limit_copy = pos.ins().copy(stack_limit_arg);
|
||||
pos.func.locations[stack_limit_copy] = ir::ValueLoc::Reg(RU::rax as RegUnit);
|
||||
let sp_threshold = pos.ins().iadd_imm(stack_limit_copy, stack_size);
|
||||
pos.func.locations[sp_threshold] = ir::ValueLoc::Reg(RU::rax as RegUnit);
|
||||
|
||||
// If the stack pointer currently reaches the SP threshold or below it then after opening
|
||||
// the current stack frame, the current stack pointer will reach the limit.
|
||||
let cflags = pos.ins().ifcmp_sp(sp_threshold);
|
||||
pos.func.locations[cflags] = ir::ValueLoc::Reg(RU::rflags as RegUnit);
|
||||
pos.ins().trapif(
|
||||
IntCC::UnsignedGreaterThanOrEqual,
|
||||
cflags,
|
||||
ir::TrapCode::StackOverflow,
|
||||
);
|
||||
}
|
||||
|
||||
/// Find all `return` instructions and insert epilogues before them.
|
||||
fn insert_common_epilogues(
|
||||
pos: &mut EncCursor,
|
||||
stack_size: i64,
|
||||
reg_type: ir::types::Type,
|
||||
csrs: &RegisterSet,
|
||||
) {
|
||||
while let Some(ebb) = pos.next_ebb() {
|
||||
pos.goto_last_inst(ebb);
|
||||
if let Some(inst) = pos.current_inst() {
|
||||
if pos.func.dfg[inst].opcode().is_return() {
|
||||
insert_common_epilogue(inst, stack_size, pos, reg_type, csrs);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Insert an epilogue given a specific `return` instruction.
|
||||
/// This is used by common calling conventions such as System V.
|
||||
fn insert_common_epilogue(
|
||||
inst: ir::Inst,
|
||||
stack_size: i64,
|
||||
pos: &mut EncCursor,
|
||||
reg_type: ir::types::Type,
|
||||
csrs: &RegisterSet,
|
||||
) {
|
||||
if stack_size > 0 {
|
||||
pos.ins().adjust_sp_up_imm(Imm64::new(stack_size));
|
||||
}
|
||||
|
||||
// Pop all the callee-saved registers, stepping backward each time to
|
||||
// preserve the correct order.
|
||||
let fp_ret = pos.ins().x86_pop(reg_type);
|
||||
pos.prev_inst();
|
||||
|
||||
pos.func.locations[fp_ret] = ir::ValueLoc::Reg(RU::rbp as RegUnit);
|
||||
pos.func.dfg.append_inst_arg(inst, fp_ret);
|
||||
|
||||
for reg in csrs.iter(GPR) {
|
||||
let csr_ret = pos.ins().x86_pop(reg_type);
|
||||
pos.prev_inst();
|
||||
|
||||
pos.func.locations[csr_ret] = ir::ValueLoc::Reg(reg);
|
||||
pos.func.dfg.append_inst_arg(inst, csr_ret);
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user