bjoernager/rust
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wasm exception handling

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This commit is contained in:
Jan-Mirko Otter 2023-05-01 19:24:21 +00:00
parent 35cdb28c84
commit 82730b4521
5 changed files with 117 additions and 14 deletions
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14
compiler/rustc_codegen_ssa/src/base.rs
View file

@ -357,6 +357,13 @@ pub fn cast_shift_expr_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
}
}
// Returns `true` if this session's target will use native wasm
// exceptions. This means that the VM does the unwinding for
// us
pub fn wants_wasm_eh(sess: &Session) -> bool {
sess.target.is_like_wasm && sess.target.os != "emscripten"
}
/// Returns `true` if this session's target will use SEH-based unwinding.
///
/// This is only true for MSVC targets, and even then the 64-bit MSVC target
@ -366,6 +373,13 @@ pub fn wants_msvc_seh(sess: &Session) -> bool {
sess.target.is_like_msvc
}
/// Returns `true` if this session's target requires the new exception
/// handling LLVM IR instructions (catchpad / cleanuppad / ... instead
/// of landingpad)
pub fn wants_new_eh_instructions(sess: &Session) -> bool {
wants_wasm_eh(sess) || wants_msvc_seh(sess)
}
pub fn memcpy_ty<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
bx: &mut Bx,
dst: Bx::Value,

17
compiler/rustc_codegen_ssa/src/mir/block.rs
View file

@ -79,8 +79,8 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
lltarget = fx.landing_pad_for(target);
}
if is_cleanupret {
// MSVC cross-funclet jump - need a trampoline
debug_assert!(base::wants_msvc_seh(fx.cx.tcx().sess));
// Cross-funclet jump - need a trampoline
debug_assert!(base::wants_new_eh_instructions(fx.cx.tcx().sess));
debug!("llbb_with_cleanup: creating cleanup trampoline for {:?}", target);
let name = &format!("{:?}_cleanup_trampoline_{:?}", self.bb, target);
let trampoline_llbb = Bx::append_block(fx.cx, fx.llfn, name);
@ -177,9 +177,16 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
mir::UnwindAction::Continue => None,
mir::UnwindAction::Unreachable => None,
mir::UnwindAction::Terminate => {
if fx.mir[self.bb].is_cleanup && base::wants_msvc_seh(fx.cx.tcx().sess) {
// SEH will abort automatically if an exception tries to
if fx.mir[self.bb].is_cleanup && base::wants_new_eh_instructions(fx.cx.tcx().sess) {
// MSVC SEH will abort automatically if an exception tries to
// propagate out from cleanup.
// FIXME(@mirkootter): For wasm, we currently do not support terminate during
// cleanup, because this requires a few more changes: The current code
// caches the `terminate_block` for each function; funclet based code - however -
// requires a different terminate_block for each funclet
// Until this is implemented, we just do not unwind inside cleanup blocks
None
} else {
Some(fx.terminate_block())
@ -1528,7 +1535,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
// FIXME(eddyb) rename this to `eh_pad_for_uncached`.
fn landing_pad_for_uncached(&mut self, bb: mir::BasicBlock) -> Bx::BasicBlock {
let llbb = self.llbb(bb);
if base::wants_msvc_seh(self.cx.sess()) {
if base::wants_new_eh_instructions(self.cx.sess()) {
let cleanup_bb = Bx::append_block(self.cx, self.llfn, &format!("funclet_{:?}", bb));
let mut cleanup_bx = Bx::build(self.cx, cleanup_bb);
let funclet = cleanup_bx.cleanup_pad(None, &[]);

3
compiler/rustc_codegen_ssa/src/mir/mod.rs
View file

@ -169,7 +169,8 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
start_bx.set_personality_fn(cx.eh_personality());
}
let cleanup_kinds = base::wants_msvc_seh(cx.tcx().sess).then(|| analyze::cleanup_kinds(&mir));
let cleanup_kinds =
base::wants_new_eh_instructions(cx.tcx().sess).then(|| analyze::cleanup_kinds(&mir));
let cached_llbbs: IndexVec<mir::BasicBlock, CachedLlbb<Bx::BasicBlock>> =
mir.basic_blocks