Cranelift: refactoring of unwind info (#2289)
* factor common code * move fde/unwind emit to more abstract level * code_len -> function_size * speedup block scanning * better function_size calciulation * Rename UnwindCode enums
This commit is contained in:
Yury Delendik
@@ -1,14 +1,9 @@
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//! Unwind information for Windows x64 ABI.
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use crate::ir::{Function, InstructionData, Opcode, ValueLoc};
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use crate::isa::x86::registers::{FPR, GPR, RU};
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use crate::isa::{
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unwind::winx64::{UnwindCode, UnwindInfo},
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CallConv, RegUnit, TargetIsa,
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};
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use crate::result::{CodegenError, CodegenResult};
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use alloc::vec::Vec;
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use log::warn;
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use crate::ir::Function;
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use crate::isa::x86::registers::{FPR, GPR};
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use crate::isa::{unwind::winx64::UnwindInfo, CallConv, RegUnit, TargetIsa};
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use crate::result::CodegenResult;
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pub(crate) fn create_unwind_info(
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func: &Function,
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@@ -19,115 +14,29 @@ pub(crate) fn create_unwind_info(
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return Ok(None);
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}
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let prologue_end = func.prologue_end.unwrap();
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let entry_block = func.layout.entry_block().expect("missing entry block");
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// Stores the stack size when SP is not adjusted via an immediate value
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let mut stack_size = None;
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let mut prologue_size = 0;
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let mut unwind_codes = Vec::new();
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let mut found_end = false;
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for (offset, inst, size) in func.inst_offsets(entry_block, &isa.encoding_info()) {
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// x64 ABI prologues cannot exceed 255 bytes in length
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if (offset + size) > 255 {
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warn!("function prologues cannot exceed 255 bytes in size for Windows x64");
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return Err(CodegenError::CodeTooLarge);
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let unwind = match super::create_unwind_info(func, isa, None)? {
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Some(u) => u,
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None => {
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return Ok(None);
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}
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};
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prologue_size += size;
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Ok(Some(UnwindInfo::build::<RegisterMapper>(unwind)?))
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}
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let unwind_offset = (offset + size) as u8;
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struct RegisterMapper;
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match func.dfg[inst] {
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InstructionData::Unary { opcode, arg } => {
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match opcode {
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Opcode::X86Push => {
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unwind_codes.push(UnwindCode::PushRegister {
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offset: unwind_offset,
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reg: GPR.index_of(func.locations[arg].unwrap_reg()) as u8,
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});
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}
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Opcode::AdjustSpDown => {
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let stack_size =
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stack_size.expect("expected a previous stack size instruction");
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// This is used when calling a stack check function
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// We need to track the assignment to RAX which has the size of the stack
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unwind_codes.push(UnwindCode::StackAlloc {
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offset: unwind_offset,
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size: stack_size,
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});
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}
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_ => {}
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}
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}
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InstructionData::UnaryImm { opcode, imm } => {
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match opcode {
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Opcode::Iconst => {
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let imm: i64 = imm.into();
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assert!(imm <= core::u32::MAX as i64);
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assert!(stack_size.is_none());
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// This instruction should only appear in a prologue to pass an
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// argument of the stack size to a stack check function.
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// Record the stack size so we know what it is when we encounter the adjustment
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// instruction (which will adjust via the register assigned to this instruction).
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stack_size = Some(imm as u32);
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}
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Opcode::AdjustSpDownImm => {
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let imm: i64 = imm.into();
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assert!(imm <= core::u32::MAX as i64);
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stack_size = Some(imm as u32);
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unwind_codes.push(UnwindCode::StackAlloc {
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offset: unwind_offset,
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size: imm as u32,
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});
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}
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_ => {}
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}
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}
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InstructionData::Store {
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opcode: Opcode::Store,
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args: [arg1, arg2],
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offset,
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..
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} => {
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if let (ValueLoc::Reg(src), ValueLoc::Reg(dst)) =
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(func.locations[arg1], func.locations[arg2])
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{
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// If this is a save of an FPR, record an unwind operation
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// Note: the stack_offset here is relative to an adjusted SP
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if dst == (RU::rsp as RegUnit) && FPR.contains(src) {
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let offset: i32 = offset.into();
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unwind_codes.push(UnwindCode::SaveXmm {
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offset: unwind_offset,
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reg: src as u8,
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stack_offset: offset as u32,
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});
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}
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}
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}
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_ => {}
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};
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if inst == prologue_end {
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found_end = true;
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break;
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impl crate::isa::unwind::winx64::RegisterMapper for RegisterMapper {
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fn map(reg: RegUnit) -> u8 {
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if GPR.contains(reg) {
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GPR.index_of(reg) as u8
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} else if FPR.contains(reg) {
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// XMM register
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reg as u8
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} else {
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panic!()
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}
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}
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assert!(found_end);
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Ok(Some(UnwindInfo {
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flags: 0, // this assumes cranelift functions have no SEH handlers
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prologue_size: prologue_size as u8,
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frame_register: None,
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frame_register_offset: 0,
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unwind_codes,
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}))
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}
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#[cfg(test)]
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@@ -135,6 +44,8 @@ mod tests {
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use super::*;
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use crate::cursor::{Cursor, FuncCursor};
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use crate::ir::{ExternalName, InstBuilder, Signature, StackSlotData, StackSlotKind};
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use crate::isa::unwind::winx64::UnwindCode;
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use crate::isa::x86::registers::RU;
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use crate::isa::{lookup, CallConv};
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use crate::settings::{builder, Flags};
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use crate::Context;
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