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Refactor unwind generation in Cranelift.

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This commit makes the following changes to unwind information generation in
Cranelift:

* Remove frame layout change implementation in favor of processing the prologue
  and epilogue instructions when unwind information is requested.  This also
  means this work is no longer performed for Windows, which didn't utilize it.
  It also helps simplify the prologue and epilogue generation code.

* Remove the unwind sink implementation that required each unwind information
  to be represented in final form. For FDEs, this meant writing a
  complete frame table per function, which wastes 20 bytes or so for each
  function with duplicate CIEs.  This also enables Cranelift users to collect the
  unwind information and write it as a single frame table.

* For System V calling convention, the unwind information is no longer stored
  in code memory (it's only a requirement for Windows ABI to do so).  This allows
  for more compact code memory for modules with a lot of functions.

* Deletes some duplicate code relating to frame table generation.  Users can
  now simply use gimli to create a frame table from each function's unwind
  information.

Fixes #1181.
This commit is contained in:
Peter Huene
2020-03-30 19:48:02 -07:00
parent 7da6101732
commit f7e9f86ba9
42 changed files with 2678 additions and 3161 deletions
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57
crates/environ/src/cranelift.rs
View File

@@ -3,10 +3,8 @@
use crate::address_map::{FunctionAddressMap, InstructionAddressMap};
use crate::cache::{ModuleCacheDataTupleType, ModuleCacheEntry};
use crate::compilation::{
Compilation, CompileError, CompiledFunction, CompiledFunctionUnwindInfo, Relocation,
RelocationTarget, TrapInformation,
Compilation, CompileError, CompiledFunction, Relocation, RelocationTarget, TrapInformation,
};
use crate::frame_layout::FrameLayout;
use crate::func_environ::{get_func_name, FuncEnvironment};
use crate::{CacheConfig, FunctionBodyData, ModuleLocal, ModuleTranslation, Tunables};
use cranelift_codegen::ir::{self, ExternalName};
@@ -154,38 +152,6 @@ fn get_function_address_map<'data>(
}
}
fn get_frame_layout(
context: &Context,
isa: &dyn isa::TargetIsa,
) -> (
Box<[ir::FrameLayoutChange]>,
Box<[(usize, ir::FrameLayoutChange)]>,
) {
let func = &context.func;
assert!(func.frame_layout.is_some(), "expected func.frame_layout");
let mut blocks = func.layout.blocks().collect::<Vec<_>>();
blocks.sort_by_key(|b| func.offsets[*b]); // Ensure inst offsets always increase
let encinfo = isa.encoding_info();
let mut last_offset = 0;
let mut commands = Vec::new();
for b in blocks {
for (offset, inst, size) in func.inst_offsets(b, &encinfo) {
if let Some(cmds) = func.frame_layout.as_ref().unwrap().instructions.get(&inst) {
let address_offset = (offset + size) as usize;
assert!(last_offset < address_offset);
for cmd in cmds.iter() {
commands.push((address_offset, cmd.clone()));
}
last_offset = address_offset;
}
}
}
let initial = func.frame_layout.as_ref().unwrap().initial.clone();
(initial, commands.into_boxed_slice())
}
/// A compiler that compiles a WebAssembly module with Cranelift, translating the Wasm to Cranelift IR,
/// optimizing it and then translating to assembly.
pub struct Cranelift;
@@ -224,7 +190,6 @@ fn compile(env: CompileEnv<'_>) -> Result<ModuleCacheDataTupleType, CompileError
let mut value_ranges = PrimaryMap::with_capacity(env.function_body_inputs.len());
let mut stack_slots = PrimaryMap::with_capacity(env.function_body_inputs.len());
let mut traps = PrimaryMap::with_capacity(env.function_body_inputs.len());
let mut frame_layouts = PrimaryMap::with_capacity(env.function_body_inputs.len());
env.function_body_inputs
.into_iter()
@@ -235,7 +200,6 @@ fn compile(env: CompileEnv<'_>) -> Result<ModuleCacheDataTupleType, CompileError
let mut context = Context::new();
context.func.name = get_func_name(func_index);
context.func.signature = env.local.signatures[env.local.functions[func_index]].clone();
context.func.collect_frame_layout_info();
if env.tunables.debug_info {
context.func.collect_debug_info();
}
@@ -264,23 +228,12 @@ fn compile(env: CompileEnv<'_>) -> Result<ModuleCacheDataTupleType, CompileError
CompileError::Codegen(pretty_error(&context.func, Some(isa), error))
})?;
let unwind_info = CompiledFunctionUnwindInfo::new(isa, &context).map_err(|error| {
let unwind_info = context.create_unwind_info(isa).map_err(|error| {
CompileError::Codegen(pretty_error(&context.func, Some(isa), error))
})?;
let address_transform = get_function_address_map(&context, input, code_buf.len(), isa);
let frame_layout = if env.tunables.debug_info {
let (initial_commands, commands) = get_frame_layout(&context, isa);
Some(FrameLayout {
call_conv: context.func.signature.call_conv,
initial_commands,
commands,
})
} else {
None
};
let ranges = if env.tunables.debug_info {
let ranges = context.build_value_labels_ranges(isa).map_err(|error| {
CompileError::Codegen(pretty_error(&context.func, Some(isa), error))
@@ -295,7 +248,6 @@ fn compile(env: CompileEnv<'_>) -> Result<ModuleCacheDataTupleType, CompileError
context.func.jt_offsets,
reloc_sink.func_relocs,
address_transform,
frame_layout,
ranges,
context.func.stack_slots,
trap_sink.traps,
@@ -310,7 +262,6 @@ fn compile(env: CompileEnv<'_>) -> Result<ModuleCacheDataTupleType, CompileError
func_jt_offsets,
relocs,
address_transform,
frame_layout,
ranges,
sss,
function_traps,
@@ -326,9 +277,6 @@ fn compile(env: CompileEnv<'_>) -> Result<ModuleCacheDataTupleType, CompileError
value_ranges.push(ranges.unwrap_or_default());
stack_slots.push(sss);
traps.push(function_traps);
if let Some(frame_layout) = frame_layout {
frame_layouts.push(frame_layout);
}
},
);
@@ -341,7 +289,6 @@ fn compile(env: CompileEnv<'_>) -> Result<ModuleCacheDataTupleType, CompileError
value_ranges,
stack_slots,
traps,
frame_layouts,
))
}