diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src/large_enums.rs')
| -rw-r--r-- | compiler/rustc_mir_transform/src/large_enums.rs | 42 |
1 files changed, 27 insertions, 15 deletions
diff --git a/compiler/rustc_mir_transform/src/large_enums.rs b/compiler/rustc_mir_transform/src/large_enums.rs index 1919720de49..3f8662ad697 100644 --- a/compiler/rustc_mir_transform/src/large_enums.rs +++ b/compiler/rustc_mir_transform/src/large_enums.rs @@ -1,6 +1,6 @@ use crate::rustc_middle::ty::util::IntTypeExt; use crate::MirPass; -use rustc_data_structures::stable_map::FxHashMap; +use rustc_data_structures::fx::FxHashMap; use rustc_middle::mir::interpret::AllocId; use rustc_middle::mir::*; use rustc_middle::ty::{self, AdtDef, Const, ParamEnv, Ty, TyCtxt}; @@ -19,6 +19,10 @@ use rustc_target::abi::{HasDataLayout, Size, TagEncoding, Variants}; /// Instead of emitting moves of the large variant, /// Perform a memcpy instead. /// Based off of [this HackMD](https://hackmd.io/@ft4bxUsFT5CEUBmRKYHr7w/rJM8BBPzD). +/// +/// In summary, what this does is at runtime determine which enum variant is active, +/// and instead of copying all the bytes of the largest possible variant, +/// copy only the bytes for the currently active variant. pub struct EnumSizeOpt { pub(crate) discrepancy: u64, } @@ -26,7 +30,10 @@ pub struct EnumSizeOpt { impl<'tcx> MirPass<'tcx> for EnumSizeOpt { fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { let sess = tcx.sess; - if (!sess.opts.debugging_opts.unsound_mir_opts) || sess.mir_opt_level() < 3 { + // FIXME(julianknodt): one thing noticed while testing this mir-opt is that there is a + // different layout of large enums on wasm. It's not clear what is causing this layout + // difference, as it should be identical to i686 (32 bit). + if (!sess.opts.unstable_opts.unsound_mir_opts) || sess.mir_opt_level() < 3 { return; } self.optim(tcx, body); @@ -56,8 +63,8 @@ impl EnumSizeOpt { Variants::Multiple { variants, .. } if variants.len() <= 1 => return None, Variants::Multiple { variants, .. } => variants, }; - let min = variants.iter().map(|v| v.size()).min().unwrap(); - let max = variants.iter().map(|v| v.size()).max().unwrap(); + let min = variants.iter().map(|v| v.size).min().unwrap(); + let max = variants.iter().map(|v| v.size).max().unwrap(); if max.bytes() - min.bytes() < self.discrepancy { return None; } @@ -92,7 +99,7 @@ impl EnumSizeOpt { for (var_idx, layout) in variants.iter_enumerated() { let curr_idx = target_bytes * adt_def.discriminant_for_variant(tcx, var_idx).val as usize; - let sz = layout.size(); + let sz = layout.size; match ptr_sized_int { rustc_target::abi::Integer::I32 => { encode_store!(curr_idx, data_layout.endian, sz.bytes() as u32); @@ -115,8 +122,11 @@ impl EnumSizeOpt { let mut alloc_cache = FxHashMap::default(); let body_did = body.source.def_id(); let param_env = tcx.param_env(body_did); - let (bbs, local_decls) = body.basic_blocks_and_local_decls_mut(); - for bb in bbs { + + let blocks = body.basic_blocks.as_mut(); + let local_decls = &mut body.local_decls; + + for bb in blocks { bb.expand_statements(|st| { if let StatementKind::Assign(box ( lhs, @@ -175,7 +185,7 @@ impl EnumSizeOpt { kind: StatementKind::Assign(box ( discr_cast_place, Rvalue::Cast( - CastKind::Misc, + CastKind::IntToInt, Operand::Copy(discr_place), tcx.types.usize, ), @@ -217,7 +227,7 @@ impl EnumSizeOpt { source_info, kind: StatementKind::Assign(box ( dst_cast_place, - Rvalue::Cast(CastKind::Misc, Operand::Copy(dst), dst_cast_ty), + Rvalue::Cast(CastKind::PtrToPtr, Operand::Copy(dst), dst_cast_ty), )), }; @@ -240,17 +250,19 @@ impl EnumSizeOpt { source_info, kind: StatementKind::Assign(box ( src_cast_place, - Rvalue::Cast(CastKind::Misc, Operand::Copy(src), src_cast_ty), + Rvalue::Cast(CastKind::PtrToPtr, Operand::Copy(src), src_cast_ty), )), }; let copy_bytes = Statement { source_info, - kind: StatementKind::CopyNonOverlapping(box CopyNonOverlapping { - src: Operand::Copy(src_cast_place), - dst: Operand::Copy(dst_cast_place), - count: Operand::Copy(size_place), - }), + kind: StatementKind::Intrinsic( + box NonDivergingIntrinsic::CopyNonOverlapping(CopyNonOverlapping { + src: Operand::Copy(src_cast_place), + dst: Operand::Copy(dst_cast_place), + count: Operand::Copy(size_place), + }), + ), }; let store_dead = Statement { |