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Properly preserve and restore CFA state in FDE (#1373)

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* Properly preserve and restore CFA state in FDE
This commit is contained in:
Yury Delendik
2020-02-03 16:08:40 -06:00
committed by GitHub
parent 3502cd3cd1
commit 169dbef784
2 changed files with 99 additions and 25 deletions
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39
cranelift/codegen/src/isa/x86/abi.rs
View File

@@ -835,25 +835,7 @@ fn insert_common_epilogues(
pos.goto_last_inst(ebb);
if let Some(inst) = pos.current_inst() {
if pos.func.dfg[inst].opcode().is_return() {
if let (Some(ref mut frame_layout), ref func_layout) =
(pos.func.frame_layout.as_mut(), &pos.func.layout)
{
// Figure out if we need to insert end-of-function-aware frame layout information.
let following_inst = func_layout
.next_ebb(ebb)
.and_then(|next_ebb| func_layout.first_inst(next_ebb));
if let Some(following_inst) = following_inst {
frame_layout
.instructions
.insert(inst, vec![FrameLayoutChange::Preserve].into_boxed_slice());
frame_layout.instructions.insert(
following_inst,
vec![FrameLayoutChange::Restore].into_boxed_slice(),
);
}
}
let is_last = pos.func.layout.last_ebb() == Some(ebb);
insert_common_epilogue(
inst,
stack_size,
@@ -861,6 +843,7 @@ fn insert_common_epilogues(
reg_type,
csrs,
isa,
is_last,
cfa_state.clone(),
);
}
@@ -877,6 +860,7 @@ fn insert_common_epilogue(
reg_type: ir::types::Type,
csrs: &RegisterSet,
isa: &dyn TargetIsa,
is_last: bool,
mut cfa_state: Option<CFAState>,
) {
let word_size = isa.pointer_bytes() as isize;
@@ -931,10 +915,16 @@ fn insert_common_epilogue(
assert_eq!(cfa_state.current_depth, -word_size);
assert_eq!(cfa_state.cf_ptr_offset, word_size);
// Inserting preserve CFA state operation after FP pop instructions.
let new_cfa = FrameLayoutChange::CallFrameAddressAt {
reg: cfa_state.cf_ptr_reg,
offset: cfa_state.cf_ptr_offset,
};
let new_cfa = if is_last {
vec![new_cfa]
} else {
vec![FrameLayoutChange::Preserve, new_cfa]
};
frame_layout
.instructions
@@ -943,10 +933,17 @@ fn insert_common_epilogue(
*insts = insts
.iter()
.cloned()
.chain(std::iter::once(new_cfa))
.chain(new_cfa.clone().into_iter())
.collect::<Box<[_]>>();
})
.or_insert_with(|| Box::new([new_cfa]));
.or_insert_with(|| new_cfa.into_boxed_slice());
if !is_last {
// Inserting restore CFA state operation after each return.
frame_layout
.instructions
.insert(inst, vec![FrameLayoutChange::Restore].into_boxed_slice());
}
}
}

85
cranelift/codegen/src/isa/x86/fde.rs
View File

@@ -163,9 +163,8 @@ fn to_cfi(
let cfa_offset = *cfa_offset as i32;
CallFrameInstruction::Offset(X86_64::RA, cfa_offset)
}
_ => {
return None;
}
FrameLayoutChange::Preserve => CallFrameInstruction::RememberState,
FrameLayoutChange::Restore => CallFrameInstruction::RestoreState,
})
}
@@ -265,7 +264,10 @@ mod tests {
use super::*;
use crate::binemit::{FrameUnwindOffset, Reloc};
use crate::cursor::{Cursor, FuncCursor};
use crate::ir::{ExternalName, InstBuilder, Signature, StackSlotData, StackSlotKind};
use crate::ir::{
types, AbiParam, ExternalName, InstBuilder, Signature, StackSlotData, StackSlotKind,
TrapCode,
};
use crate::isa::{lookup, CallConv};
use crate::settings::{builder, Flags};
use crate::Context;
@@ -352,4 +354,79 @@ mod tests {
func
}
#[test]
fn test_multi_return_func() {
let isa = lookup(triple!("x86_64"))
.expect("expect x86 ISA")
.finish(Flags::new(builder()));
let mut context = Context::for_function(create_multi_return_function(CallConv::SystemV));
context.func.collect_frame_layout_info();
context.compile(&*isa).expect("expected compilation");
let mut sink = SimpleUnwindSink(Vec::new(), 0, Vec::new());
emit_fde(&context.func, &*isa, &mut sink);
assert_eq!(
sink.0,
vec![
20, 0, 0, 0, // CIE len
0, 0, 0, 0, // CIE marker
1, // version
0, // augmentation string
1, // code aligment = 1
120, // data alignment = -8
16, // RA = r16
0x0c, 0x07, 0x08, // DW_CFA_def_cfa r7, 8
0x90, 0x01, // DW_CFA_offset r16, -8 * 1
0, 0, 0, 0, 0, 0, // padding
36, 0, 0, 0, // FDE len
28, 0, 0, 0, // CIE offset
0, 0, 0, 0, 0, 0, 0, 0, // addr reloc
15, 0, 0, 0, 0, 0, 0, 0, // function length
0x42, // DW_CFA_advance_loc 2
0x0e, 0x10, // DW_CFA_def_cfa_offset 16
0x86, 0x02, // DW_CFA_offset r6, -8 * 2
0x43, // DW_CFA_advance_loc 3
0x0d, 0x06, // DW_CFA_def_cfa_register
0x47, // DW_CFA_advance_loc 10
0x0a, // DW_CFA_preserve_state
0x0c, 0x07, 0x08, // DW_CFA_def_cfa r7, 8
0x41, // DW_CFA_advance_loc 1
0x0b, // DW_CFA_restore_state
// NOTE: no additional CFA directives -- DW_CFA_restore_state
// is done before trap and it is last instruction in the function.
0, // padding
0, 0, 0, 0, // End of FDEs
]
);
assert_eq!(sink.1, 24);
assert_eq!(sink.2.len(), 1);
}
fn create_multi_return_function(call_conv: CallConv) -> Function {
let mut sig = Signature::new(call_conv);
sig.params.push(AbiParam::new(types::I32));
let mut func = Function::with_name_signature(ExternalName::user(0, 0), sig);
let ebb0 = func.dfg.make_ebb();
let v0 = func.dfg.append_ebb_param(ebb0, types::I32);
let ebb1 = func.dfg.make_ebb();
let ebb2 = func.dfg.make_ebb();
let mut pos = FuncCursor::new(&mut func);
pos.insert_ebb(ebb0);
pos.ins().brnz(v0, ebb2, &[]);
pos.ins().jump(ebb1, &[]);
pos.insert_ebb(ebb1);
pos.ins().return_(&[]);
pos.insert_ebb(ebb2);
pos.ins().trap(TrapCode::User(0));
func
}
}