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cranelift: refactor unwind logic to accommodate multiple backends (#2357)

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*    Make cranelift_codegen::isa::unwind::input public
*    Move UnwindCode's common offset field out of the structure
*    Make MachCompileResult::unwind_info more generic
*    Record initial stack pointer offset
This commit is contained in:
Yury Delendik
2020-11-05 16:57:40 -06:00
committed by GitHub
parent df59ffb1b6
commit f60c0f3ec3
15 changed files with 396 additions and 351 deletions
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137
cranelift/codegen/src/isa/x64/inst/unwind.rs
View File

@@ -1,36 +1,125 @@
use super::Inst;
use crate::isa::unwind::UnwindInfo;
use crate::machinst::{UnwindInfoContext, UnwindInfoGenerator, UnwindInfoKind};
use crate::isa::unwind::input::UnwindInfo;
use crate::isa::x64::inst::{
args::{AluRmiROpcode, Amode, RegMemImm, SyntheticAmode},
regs, Inst,
};
use crate::machinst::{UnwindInfoContext, UnwindInfoGenerator};
use crate::result::CodegenResult;
use alloc::vec::Vec;
use regalloc::Reg;
#[cfg(feature = "unwind")]
pub use self::systemv::create_cie;
#[cfg(feature = "unwind")]
mod systemv;
pub(crate) mod systemv;
pub struct X64UnwindInfo;
impl UnwindInfoGenerator<Inst> for X64UnwindInfo {
#[allow(unused_variables)]
fn create_unwind_info(
context: UnwindInfoContext<Inst>,
kind: UnwindInfoKind,
) -> CodegenResult<Option<UnwindInfo>> {
// Assumption: RBP is being used as the frame pointer for both calling conventions
// In the future, we should be omitting frame pointer as an optimization, so this will change
Ok(match kind {
#[cfg(feature = "unwind")]
UnwindInfoKind::SystemV => {
const WORD_SIZE: u8 = 8;
systemv::create_unwind_info(context, WORD_SIZE)?.map(UnwindInfo::SystemV)
) -> CodegenResult<Option<UnwindInfo<Reg>>> {
use crate::isa::unwind::input::{self, UnwindCode};
let mut codes = Vec::new();
const WORD_SIZE: u8 = 8;
for i in context.prologue.clone() {
let i = i as usize;
let inst = &context.insts[i];
let offset = context.insts_layout[i];
match inst {
Inst::Push64 {
src: RegMemImm::Reg { reg },
} => {
codes.push((
offset,
UnwindCode::StackAlloc {
size: WORD_SIZE.into(),
},
));
codes.push((
offset,
UnwindCode::SaveRegister {
reg: *reg,
stack_offset: 0,
},
));
}
Inst::MovRR { src, dst, .. } => {
if *src == regs::rsp() {
codes.push((offset, UnwindCode::SetFramePointer { reg: dst.to_reg() }));
}
}
Inst::AluRmiR {
is_64: true,
op: AluRmiROpcode::Sub,
src: RegMemImm::Imm { simm32 },
dst,
..
} if dst.to_reg() == regs::rsp() => {
let imm = *simm32;
codes.push((offset, UnwindCode::StackAlloc { size: imm }));
}
Inst::MovRM {
src,
dst: SyntheticAmode::Real(Amode::ImmReg { simm32, base }),
..
} if *base == regs::rsp() => {
// `mov reg, imm(rsp)`
let imm = *simm32;
codes.push((
offset,
UnwindCode::SaveRegister {
reg: *src,
stack_offset: imm,
},
));
}
Inst::AluRmiR {
is_64: true,
op: AluRmiROpcode::Add,
src: RegMemImm::Imm { simm32 },
dst,
..
} if dst.to_reg() == regs::rsp() => {
let imm = *simm32;
codes.push((offset, UnwindCode::StackDealloc { size: imm }));
}
_ => {}
}
#[cfg(feature = "unwind")]
UnwindInfoKind::Windows => {
//TODO winx64::create_unwind_info(context)?.map(|u| UnwindInfo::WindowsX64(u))
panic!();
}
UnwindInfoKind::None => None,
})
}
let last_epilogue_end = context.len;
let epilogues_unwind_codes = context
.epilogues
.iter()
.map(|epilogue| {
// TODO add logic to process epilogue instruction instead of
// returning empty array.
let end = epilogue.end as usize - 1;
let end_offset = context.insts_layout[end];
if end_offset == last_epilogue_end {
// Do not remember/restore for very last epilogue.
return vec![];
}
let start = epilogue.start as usize;
let offset = context.insts_layout[start];
vec![
(offset, UnwindCode::RememberState),
// TODO epilogue instructions
(end_offset, UnwindCode::RestoreState),
]
})
.collect();
let prologue_size = context.insts_layout[context.prologue.end as usize];
Ok(Some(input::UnwindInfo {
prologue_size,
prologue_unwind_codes: codes,
epilogues_unwind_codes,
function_size: context.len,
word_size: WORD_SIZE,
initial_sp_offset: WORD_SIZE,
}))
}
}

111
cranelift/codegen/src/isa/x64/inst/unwind/systemv.rs
View File

@@ -1,13 +1,8 @@
//! Unwind information for System V ABI (x86-64).
use crate::isa::unwind::input;
use crate::isa::unwind::systemv::{RegisterMappingError, UnwindInfo};
use crate::isa::x64::inst::{
args::{AluRmiROpcode, Amode, RegMemImm, SyntheticAmode},
regs, Inst,
};
use crate::machinst::UnwindInfoContext;
use crate::result::CodegenResult;
use alloc::vec::Vec;
use gimli::{write::CommonInformationEntry, Encoding, Format, Register, X86_64};
use regalloc::{Reg, RegClass};
@@ -88,113 +83,15 @@ pub fn map_reg(reg: Reg) -> Result<Register, RegisterMappingError> {
}
pub(crate) fn create_unwind_info(
context: UnwindInfoContext<Inst>,
word_size: u8,
unwind: input::UnwindInfo<Reg>,
) -> CodegenResult<Option<UnwindInfo>> {
use crate::isa::unwind::input::{self, UnwindCode};
let mut codes = Vec::new();
for i in context.prologue.clone() {
let i = i as usize;
let inst = &context.insts[i];
let offset = context.insts_layout[i];
match inst {
Inst::Push64 {
src: RegMemImm::Reg { reg },
} => {
codes.push(UnwindCode::StackAlloc {
offset,
size: word_size.into(),
});
codes.push(UnwindCode::SaveRegister {
offset,
reg: *reg,
stack_offset: 0,
});
}
Inst::MovRR { src, dst, .. } => {
if *src == regs::rsp() {
codes.push(UnwindCode::SetFramePointer {
offset,
reg: dst.to_reg(),
});
}
}
Inst::AluRmiR {
is_64: true,
op: AluRmiROpcode::Sub,
src: RegMemImm::Imm { simm32 },
dst,
..
} if dst.to_reg() == regs::rsp() => {
let imm = *simm32;
codes.push(UnwindCode::StackAlloc { offset, size: imm });
}
Inst::MovRM {
src,
dst: SyntheticAmode::Real(Amode::ImmReg { simm32, base }),
..
} if *base == regs::rsp() => {
// `mov reg, imm(rsp)`
let imm = *simm32;
codes.push(UnwindCode::SaveRegister {
offset,
reg: *src,
stack_offset: imm,
});
}
Inst::AluRmiR {
is_64: true,
op: AluRmiROpcode::Add,
src: RegMemImm::Imm { simm32 },
dst,
..
} if dst.to_reg() == regs::rsp() => {
let imm = *simm32;
codes.push(UnwindCode::StackDealloc { offset, size: imm });
}
_ => {}
}
}
let last_epilogue_end = context.len;
let epilogues_unwind_codes = context
.epilogues
.iter()
.map(|epilogue| {
let end = epilogue.end as usize - 1;
let end_offset = context.insts_layout[end];
if end_offset == last_epilogue_end {
// Do not remember/restore for very last epilogue.
return vec![];
}
let start = epilogue.start as usize;
let offset = context.insts_layout[start];
vec![
UnwindCode::RememberState { offset },
UnwindCode::RestoreState { offset: end_offset },
]
})
.collect();
let prologue_size = context.insts_layout[context.prologue.end as usize];
let unwind = input::UnwindInfo {
prologue_size,
prologue_unwind_codes: codes,
epilogues_unwind_codes,
function_size: context.len,
word_size,
};
struct RegisterMapper;
impl crate::isa::unwind::systemv::RegisterMapper<Reg> for RegisterMapper {
fn map(&self, reg: Reg) -> Result<u16, RegisterMappingError> {
Ok(map_reg(reg)?.0)
}
fn rsp(&self) -> u16 {
map_reg(regs::rsp()).unwrap().0
fn sp(&self) -> u16 {
X86_64::RSP.0
}
}
let map = RegisterMapper;

23
cranelift/codegen/src/isa/x64/mod.rs
View File

@@ -103,10 +103,29 @@ impl MachBackend for X64Backend {
IntCC::UnsignedGreaterThanOrEqual
}
#[cfg(feature = "unwind")]
fn emit_unwind_info(
&self,
result: &MachCompileResult,
kind: crate::machinst::UnwindInfoKind,
) -> CodegenResult<Option<crate::isa::unwind::UnwindInfo>> {
use crate::isa::unwind::UnwindInfo;
use crate::machinst::UnwindInfoKind;
Ok(match (result.unwind_info.as_ref(), kind) {
(Some(info), UnwindInfoKind::SystemV) => {
inst::unwind::systemv::create_unwind_info(info.clone())?.map(UnwindInfo::SystemV)
}
(Some(_info), UnwindInfoKind::Windows) => {
//TODO inst::unwind::winx64::create_unwind_info(info.clone())?.map(|u| UnwindInfo::WindowsX64(u))
None
}
_ => None,
})
}
#[cfg(feature = "unwind")]
fn create_systemv_cie(&self) -> Option<gimli::write::CommonInformationEntry> {
// By default, an ISA cannot create a System V CIE
Some(inst::unwind::create_cie())
Some(inst::unwind::systemv::create_cie())
}
}