From 2ceea9ae9da6da4d522518d60cd22ac239ff0b9b Mon Sep 17 00:00:00 2001 From: Arpad Borsos Date: Mon, 21 Aug 2023 15:31:59 +0200 Subject: Inline functions called from `add_coverage` This removes quite a bit of indirection and duplicated code related to getting the `FunctionCoverage`. --- .../rustc_codegen_llvm/src/coverageinfo/mod.rs | 169 ++++++--------------- 1 file changed, 46 insertions(+), 123 deletions(-) (limited to 'compiler/rustc_codegen_llvm/src') diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs index 621fd36b2a3..c70cb670e96 100644 --- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs @@ -16,7 +16,7 @@ use rustc_hir as hir; use rustc_hir::def_id::DefId; use rustc_llvm::RustString; use rustc_middle::bug; -use rustc_middle::mir::coverage::{CodeRegion, CounterId, CoverageKind, ExpressionId, Op, Operand}; +use rustc_middle::mir::coverage::{CounterId, CoverageKind}; use rustc_middle::mir::Coverage; use rustc_middle::ty; use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt}; @@ -104,144 +104,67 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> { fn add_coverage(&mut self, instance: Instance<'tcx>, coverage: &Coverage) { let bx = self; + let Some(coverage_context) = bx.coverage_context() else { return }; + let mut coverage_map = coverage_context.function_coverage_map.borrow_mut(); + let func_coverage = coverage_map + .entry(instance) + .or_insert_with(|| FunctionCoverage::new(bx.tcx(), instance)); + let Coverage { kind, code_region } = coverage.clone(); match kind { CoverageKind::Counter { function_source_hash, id } => { - if bx.set_function_source_hash(instance, function_source_hash) { - // If `set_function_source_hash()` returned true, the coverage map is enabled, - // so continue adding the counter. - if let Some(code_region) = code_region { - // Note: Some counters do not have code regions, but may still be referenced - // from expressions. In that case, don't add the counter to the coverage map, - // but do inject the counter intrinsic. - bx.add_coverage_counter(instance, id, code_region); - } - - let coverageinfo = bx.tcx().coverageinfo(instance.def); - - let fn_name = bx.get_pgo_func_name_var(instance); - let hash = bx.const_u64(function_source_hash); - let num_counters = bx.const_u32(coverageinfo.num_counters); - let index = bx.const_u32(id.as_u32()); + debug!( + "ensuring function source hash is set for instance={:?}; function_source_hash={}", + instance, function_source_hash, + ); + func_coverage.set_function_source_hash(function_source_hash); + + if let Some(code_region) = code_region { + // Note: Some counters do not have code regions, but may still be referenced + // from expressions. In that case, don't add the counter to the coverage map, + // but do inject the counter intrinsic. debug!( - "codegen intrinsic instrprof.increment(fn_name={:?}, hash={:?}, num_counters={:?}, index={:?})", - fn_name, hash, num_counters, index, + "adding counter to coverage_map: instance={:?}, id={:?}, region={:?}", + instance, id, code_region, ); - bx.instrprof_increment(fn_name, hash, num_counters, index); + func_coverage.add_counter(id, code_region); } + // We need to explicitly drop the `RefMut` before calling into `instrprof_increment`, + // as that needs an exclusive borrow. + drop(coverage_map); + + let coverageinfo = bx.tcx().coverageinfo(instance.def); + + let fn_name = bx.get_pgo_func_name_var(instance); + let hash = bx.const_u64(function_source_hash); + let num_counters = bx.const_u32(coverageinfo.num_counters); + let index = bx.const_u32(id.as_u32()); + debug!( + "codegen intrinsic instrprof.increment(fn_name={:?}, hash={:?}, num_counters={:?}, index={:?})", + fn_name, hash, num_counters, index, + ); + bx.instrprof_increment(fn_name, hash, num_counters, index); } CoverageKind::Expression { id, lhs, op, rhs } => { - bx.add_coverage_counter_expression(instance, id, lhs, op, rhs, code_region); + debug!( + "adding counter expression to coverage_map: instance={:?}, id={:?}, {:?} {:?} {:?}; region: {:?}", + instance, id, lhs, op, rhs, code_region, + ); + func_coverage.add_counter_expression(id, lhs, op, rhs, code_region); } CoverageKind::Unreachable => { - bx.add_coverage_unreachable( - instance, - code_region.expect("unreachable regions always have code regions"), + let code_region = + code_region.expect("unreachable regions always have code regions"); + debug!( + "adding unreachable code to coverage_map: instance={:?}, at {:?}", + instance, code_region, ); + func_coverage.add_unreachable_region(code_region); } } } } -// These methods used to be part of trait `CoverageInfoBuilderMethods`, but -// after moving most coverage code out of SSA they are now just ordinary methods. -impl<'tcx> Builder<'_, '_, 'tcx> { - /// Returns true if the function source hash was added to the coverage map (even if it had - /// already been added, for this instance). Returns false *only* if `-C instrument-coverage` is - /// not enabled (a coverage map is not being generated). - fn set_function_source_hash( - &mut self, - instance: Instance<'tcx>, - function_source_hash: u64, - ) -> bool { - if let Some(coverage_context) = self.coverage_context() { - debug!( - "ensuring function source hash is set for instance={:?}; function_source_hash={}", - instance, function_source_hash, - ); - let mut coverage_map = coverage_context.function_coverage_map.borrow_mut(); - coverage_map - .entry(instance) - .or_insert_with(|| FunctionCoverage::new(self.tcx, instance)) - .set_function_source_hash(function_source_hash); - true - } else { - false - } - } - - /// Returns true if the counter was added to the coverage map; false if `-C instrument-coverage` - /// is not enabled (a coverage map is not being generated). - fn add_coverage_counter( - &mut self, - instance: Instance<'tcx>, - id: CounterId, - region: CodeRegion, - ) -> bool { - if let Some(coverage_context) = self.coverage_context() { - debug!( - "adding counter to coverage_map: instance={:?}, id={:?}, region={:?}", - instance, id, region, - ); - let mut coverage_map = coverage_context.function_coverage_map.borrow_mut(); - coverage_map - .entry(instance) - .or_insert_with(|| FunctionCoverage::new(self.tcx, instance)) - .add_counter(id, region); - true - } else { - false - } - } - - /// Returns true if the expression was added to the coverage map; false if - /// `-C instrument-coverage` is not enabled (a coverage map is not being generated). - fn add_coverage_counter_expression( - &mut self, - instance: Instance<'tcx>, - id: ExpressionId, - lhs: Operand, - op: Op, - rhs: Operand, - region: Option, - ) -> bool { - if let Some(coverage_context) = self.coverage_context() { - debug!( - "adding counter expression to coverage_map: instance={:?}, id={:?}, {:?} {:?} {:?}; \ - region: {:?}", - instance, id, lhs, op, rhs, region, - ); - let mut coverage_map = coverage_context.function_coverage_map.borrow_mut(); - coverage_map - .entry(instance) - .or_insert_with(|| FunctionCoverage::new(self.tcx, instance)) - .add_counter_expression(id, lhs, op, rhs, region); - true - } else { - false - } - } - - /// Returns true if the region was added to the coverage map; false if `-C instrument-coverage` - /// is not enabled (a coverage map is not being generated). - fn add_coverage_unreachable(&mut self, instance: Instance<'tcx>, region: CodeRegion) -> bool { - if let Some(coverage_context) = self.coverage_context() { - debug!( - "adding unreachable code to coverage_map: instance={:?}, at {:?}", - instance, region, - ); - let mut coverage_map = coverage_context.function_coverage_map.borrow_mut(); - coverage_map - .entry(instance) - .or_insert_with(|| FunctionCoverage::new(self.tcx, instance)) - .add_unreachable_region(region); - true - } else { - false - } - } -} - fn declare_unused_fn<'tcx>(cx: &CodegenCx<'_, 'tcx>, def_id: DefId) -> Instance<'tcx> { let tcx = cx.tcx; -- cgit 1.4.1-3-g733a5 From 56b767322b87917ea82bad6472593efa839437f9 Mon Sep 17 00:00:00 2001 From: Katherine Philip Date: Mon, 28 Aug 2023 12:40:39 -0700 Subject: Don't ICE on layout computation failure --- compiler/rustc_codegen_cranelift/src/common.rs | 2 +- compiler/rustc_codegen_gcc/src/context.rs | 3 ++- compiler/rustc_codegen_llvm/src/context.rs | 3 ++- compiler/rustc_codegen_ssa/messages.ftl | 2 ++ compiler/rustc_codegen_ssa/src/errors.rs | 10 +++++++++ compiler/rustc_middle/src/ty/layout.rs | 10 ++++++++- tests/ui/layout/layout-cycle.rs | 31 ++++++++++++++++++++++++++ tests/ui/layout/layout-cycle.stderr | 11 +++++++++ 8 files changed, 68 insertions(+), 4 deletions(-) create mode 100644 tests/ui/layout/layout-cycle.rs create mode 100644 tests/ui/layout/layout-cycle.stderr (limited to 'compiler/rustc_codegen_llvm/src') diff --git a/compiler/rustc_codegen_cranelift/src/common.rs b/compiler/rustc_codegen_cranelift/src/common.rs index 3081dcfa2b7..ec2da39398b 100644 --- a/compiler/rustc_codegen_cranelift/src/common.rs +++ b/compiler/rustc_codegen_cranelift/src/common.rs @@ -480,7 +480,7 @@ impl<'tcx> LayoutOfHelpers<'tcx> for RevealAllLayoutCx<'tcx> { if let LayoutError::SizeOverflow(_) | LayoutError::ReferencesError(_) = err { self.0.sess.span_fatal(span, err.to_string()) } else { - span_bug!(span, "failed to get layout for `{}`: {}", ty, err) + self.0.sess.span_fatal(span, format!("failed to get layout for `{}`: {}", ty, err)) } } } diff --git a/compiler/rustc_codegen_gcc/src/context.rs b/compiler/rustc_codegen_gcc/src/context.rs index 88dcafa7370..dcebd92a61c 100644 --- a/compiler/rustc_codegen_gcc/src/context.rs +++ b/compiler/rustc_codegen_gcc/src/context.rs @@ -7,6 +7,7 @@ use rustc_codegen_ssa::traits::{ BaseTypeMethods, MiscMethods, }; +use rustc_codegen_ssa::errors as ssa_errors; use rustc_data_structures::base_n; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_middle::span_bug; @@ -479,7 +480,7 @@ impl<'gcc, 'tcx> LayoutOfHelpers<'tcx> for CodegenCx<'gcc, 'tcx> { if let LayoutError::SizeOverflow(_) | LayoutError::ReferencesError(_) = err { self.sess().emit_fatal(respan(span, err.into_diagnostic())) } else { - span_bug!(span, "failed to get layout for `{}`: {}", ty, err) + self.tcx.sess.emit_fatal(ssa_errors::FailedToGetLayout { span, ty, err }) } } } diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs index 24fd5bbf8c5..8e8290279ab 100644 --- a/compiler/rustc_codegen_llvm/src/context.rs +++ b/compiler/rustc_codegen_llvm/src/context.rs @@ -10,6 +10,7 @@ use crate::value::Value; use cstr::cstr; use rustc_codegen_ssa::base::{wants_msvc_seh, wants_wasm_eh}; +use rustc_codegen_ssa::errors as ssa_errors; use rustc_codegen_ssa::traits::*; use rustc_data_structures::base_n; use rustc_data_structures::fx::FxHashMap; @@ -1000,7 +1001,7 @@ impl<'tcx> LayoutOfHelpers<'tcx> for CodegenCx<'_, 'tcx> { if let LayoutError::SizeOverflow(_) | LayoutError::ReferencesError(_) = err { self.sess().emit_fatal(Spanned { span, node: err.into_diagnostic() }) } else { - span_bug!(span, "failed to get layout for `{ty}`: {err:?}") + self.tcx.sess.emit_fatal(ssa_errors::FailedToGetLayout { span, ty, err }) } } } diff --git a/compiler/rustc_codegen_ssa/messages.ftl b/compiler/rustc_codegen_ssa/messages.ftl index b6c70c62249..3dc83f50b21 100644 --- a/compiler/rustc_codegen_ssa/messages.ftl +++ b/compiler/rustc_codegen_ssa/messages.ftl @@ -35,6 +35,8 @@ codegen_ssa_extract_bundled_libs_parse_archive = failed to parse archive '{$rlib codegen_ssa_extract_bundled_libs_read_entry = failed to read entry '{$rlib}': {$error} codegen_ssa_extract_bundled_libs_write_file = failed to write file '{$rlib}': {$error} +codegen_ssa_failed_to_get_layout = failed to get layout for {$ty}: {$err} + codegen_ssa_failed_to_write = failed to write {$path}: {$error} codegen_ssa_ignoring_emit_path = ignoring emit path because multiple .{$extension} files were produced diff --git a/compiler/rustc_codegen_ssa/src/errors.rs b/compiler/rustc_codegen_ssa/src/errors.rs index b7d8b9b45bf..41602321ded 100644 --- a/compiler/rustc_codegen_ssa/src/errors.rs +++ b/compiler/rustc_codegen_ssa/src/errors.rs @@ -7,6 +7,7 @@ use rustc_errors::{ IntoDiagnosticArg, }; use rustc_macros::Diagnostic; +use rustc_middle::ty::layout::LayoutError; use rustc_middle::ty::Ty; use rustc_span::{Span, Symbol}; use rustc_type_ir::FloatTy; @@ -1030,6 +1031,15 @@ pub struct TargetFeatureSafeTrait { pub def: Span, } +#[derive(Diagnostic)] +#[diag(codegen_ssa_failed_to_get_layout)] +pub struct FailedToGetLayout<'tcx> { + #[primary_span] + pub span: Span, + pub ty: Ty<'tcx>, + pub err: LayoutError<'tcx>, +} + #[derive(Diagnostic)] #[diag(codegen_ssa_error_creating_remark_dir)] pub struct ErrorCreatingRemarkDir { diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs index e362b3477c9..9a0e72d7b64 100644 --- a/compiler/rustc_middle/src/ty/layout.rs +++ b/compiler/rustc_middle/src/ty/layout.rs @@ -4,7 +4,9 @@ use crate::query::TyCtxtAt; use crate::ty::normalize_erasing_regions::NormalizationError; use crate::ty::{self, ConstKind, ReprOptions, Ty, TyCtxt, TypeVisitableExt}; use rustc_error_messages::DiagnosticMessage; -use rustc_errors::{DiagnosticBuilder, Handler, IntoDiagnostic}; +use rustc_errors::{ + DiagnosticArgValue, DiagnosticBuilder, Handler, IntoDiagnostic, IntoDiagnosticArg, +}; use rustc_hir as hir; use rustc_hir::def_id::DefId; use rustc_index::IndexVec; @@ -265,6 +267,12 @@ impl<'tcx> fmt::Display for LayoutError<'tcx> { } } +impl<'tcx> IntoDiagnosticArg for LayoutError<'tcx> { + fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> { + self.to_string().into_diagnostic_arg() + } +} + #[derive(Clone, Copy)] pub struct LayoutCx<'tcx, C> { pub tcx: C, diff --git a/tests/ui/layout/layout-cycle.rs b/tests/ui/layout/layout-cycle.rs new file mode 100644 index 00000000000..85685058e49 --- /dev/null +++ b/tests/ui/layout/layout-cycle.rs @@ -0,0 +1,31 @@ +// build-fail +//~^ ERROR: a cycle occurred during layout computation +//~| ERROR: cycle detected when computing layout of + +// Issue #111176 -- ensure that we do not emit ICE on layout cycles + +use std::mem; + +pub struct S { + pub f: ::I, +} + +pub trait Tr { + type I: Tr; +} + +impl Tr for S { + type I = S>; +} + +impl Tr for () { + type I = (); +} + +fn foo() -> usize { + mem::size_of::>() +} + +fn main() { + println!("{}", foo::>()); +} diff --git a/tests/ui/layout/layout-cycle.stderr b/tests/ui/layout/layout-cycle.stderr new file mode 100644 index 00000000000..a3cdb7edcc2 --- /dev/null +++ b/tests/ui/layout/layout-cycle.stderr @@ -0,0 +1,11 @@ +error[E0391]: cycle detected when computing layout of `S>` + | + = note: ...which requires computing layout of ` as Tr>::I`... + = note: ...which again requires computing layout of `S>`, completing the cycle + = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information + +error: failed to get layout for S>: a cycle occurred during layout computation + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0391`. -- cgit 1.4.1-3-g733a5 From b2ebf1c23f93886ba7d3738878f04e275add4ead Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Sun, 27 Aug 2023 18:12:34 +0200 Subject: const_eval and codegen: audit uses of is_zst --- compiler/rustc_codegen_cranelift/src/unsize.rs | 4 +++- compiler/rustc_codegen_cranelift/src/vtable.rs | 4 ++-- .../rustc_codegen_llvm/src/debuginfo/metadata.rs | 4 ++-- compiler/rustc_codegen_ssa/src/base.rs | 8 +++++--- compiler/rustc_codegen_ssa/src/mir/block.rs | 13 +++++++------ compiler/rustc_codegen_ssa/src/mir/mod.rs | 2 +- compiler/rustc_codegen_ssa/src/mir/operand.rs | 3 ++- compiler/rustc_codegen_ssa/src/mir/place.rs | 3 ++- compiler/rustc_codegen_ssa/src/mir/rvalue.rs | 1 + compiler/rustc_const_eval/src/interpret/cast.rs | 20 ++++++++++++-------- compiler/rustc_const_eval/src/interpret/operand.rs | 1 + .../rustc_const_eval/src/interpret/terminator.rs | 8 ++++---- 12 files changed, 42 insertions(+), 29 deletions(-) (limited to 'compiler/rustc_codegen_llvm/src') diff --git a/compiler/rustc_codegen_cranelift/src/unsize.rs b/compiler/rustc_codegen_cranelift/src/unsize.rs index 6aeba13f639..c6133f2b35c 100644 --- a/compiler/rustc_codegen_cranelift/src/unsize.rs +++ b/compiler/rustc_codegen_cranelift/src/unsize.rs @@ -88,7 +88,8 @@ fn unsize_ptr<'tcx>( let src_f = src_layout.field(fx, i); assert_eq!(src_layout.fields.offset(i).bytes(), 0); assert_eq!(dst_layout.fields.offset(i).bytes(), 0); - if src_f.is_zst() { + if src_f.is_1zst() { + // We are looking for the one non-1-ZST field; this is not it. continue; } assert_eq!(src_layout.size, src_f.size); @@ -151,6 +152,7 @@ pub(crate) fn coerce_unsized_into<'tcx>( let dst_f = dst.place_field(fx, FieldIdx::new(i)); if dst_f.layout().is_zst() { + // No data here, nothing to copy/coerce. continue; } diff --git a/compiler/rustc_codegen_cranelift/src/vtable.rs b/compiler/rustc_codegen_cranelift/src/vtable.rs index b309695c190..7598c6eee03 100644 --- a/compiler/rustc_codegen_cranelift/src/vtable.rs +++ b/compiler/rustc_codegen_cranelift/src/vtable.rs @@ -51,8 +51,8 @@ pub(crate) fn get_ptr_and_method_ref<'tcx>( 'descend_newtypes: while !arg.layout().ty.is_unsafe_ptr() && !arg.layout().ty.is_ref() { for i in 0..arg.layout().fields.count() { let field = arg.value_field(fx, FieldIdx::new(i)); - if !field.layout().is_zst() { - // we found the one non-zero-sized field that is allowed + if !field.layout().is_1zst() { + // we found the one non-1-ZST field that is allowed // now find *its* non-zero-sized field, or stop if it's a // pointer arg = field; diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs index f8cbcbd5ec8..ed938761694 100644 --- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs +++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs @@ -445,9 +445,9 @@ pub fn type_di_node<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, t: Ty<'tcx>) -> &'ll D ty::RawPtr(ty::TypeAndMut { ty: pointee_type, .. }) | ty::Ref(_, pointee_type, _) => { build_pointer_or_reference_di_node(cx, t, pointee_type, unique_type_id) } - // Box may have a non-ZST allocator A. In that case, we + // Box may have a non-1-ZST allocator A. In that case, we // cannot treat Box as just an owned alias of `*mut T`. - ty::Adt(def, args) if def.is_box() && cx.layout_of(args.type_at(1)).is_zst() => { + ty::Adt(def, args) if def.is_box() && cx.layout_of(args.type_at(1)).is_1zst() => { build_pointer_or_reference_di_node(cx, t, t.boxed_ty(), unique_type_id) } ty::FnDef(..) | ty::FnPtr(_) => build_subroutine_type_di_node(cx, unique_type_id), diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs index aa003e4e898..cd19885faa0 100644 --- a/compiler/rustc_codegen_ssa/src/base.rs +++ b/compiler/rustc_codegen_ssa/src/base.rs @@ -202,7 +202,7 @@ pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( (src, unsized_info(bx, a, b, old_info)) } (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => { - assert_eq!(def_a, def_b); + assert_eq!(def_a, def_b); // implies same number of fields let src_layout = bx.cx().layout_of(src_ty); let dst_layout = bx.cx().layout_of(dst_ty); if src_ty == dst_ty { @@ -211,7 +211,8 @@ pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( let mut result = None; for i in 0..src_layout.fields.count() { let src_f = src_layout.field(bx.cx(), i); - if src_f.is_zst() { + if src_f.is_1zst() { + // We are looking for the one non-1-ZST field; this is not it. continue; } @@ -272,13 +273,14 @@ pub fn coerce_unsized_into<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( } (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => { - assert_eq!(def_a, def_b); + assert_eq!(def_a, def_b); // implies same number of fields for i in def_a.variant(FIRST_VARIANT).fields.indices() { let src_f = src.project_field(bx, i.as_usize()); let dst_f = dst.project_field(bx, i.as_usize()); if dst_f.layout.is_zst() { + // No data here, nothing to copy/coerce. continue; } diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs index 6aef1664394..d78a0c49107 100644 --- a/compiler/rustc_codegen_ssa/src/mir/block.rs +++ b/compiler/rustc_codegen_ssa/src/mir/block.rs @@ -933,8 +933,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { { for i in 0..op.layout.fields.count() { let field = op.extract_field(bx, i); - if !field.layout.is_zst() { - // we found the one non-zero-sized field that is allowed + if !field.layout.is_1zst() { + // we found the one non-1-ZST field that is allowed // now find *its* non-zero-sized field, or stop if it's a // pointer op = field; @@ -975,10 +975,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { { for i in 0..op.layout.fields.count() { let field = op.extract_field(bx, i); - if !field.layout.is_zst() { - // we found the one non-zero-sized field that is allowed - // now find *its* non-zero-sized field, or stop if it's a - // pointer + if !field.layout.is_1zst() { + // We found the one non-1-ZST field that is allowed. (The rules + // for `DispatchFromDyn` ensure there's exactly one such field.) + // Now find *its* non-zero-sized field, or stop if it's a + // pointer. op = field; continue 'descend_newtypes; } diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs index 3d0c17e9cfb..bf937c2fc7c 100644 --- a/compiler/rustc_codegen_ssa/src/mir/mod.rs +++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs @@ -145,7 +145,7 @@ impl<'tcx, V: CodegenObject> LocalRef<'tcx, V> { if layout.is_zst() { // Zero-size temporaries aren't always initialized, which // doesn't matter because they don't contain data, but - // we need something in the operand. + // we need something sufficiently aligned in the operand. LocalRef::Operand(OperandRef::zero_sized(layout)) } else { LocalRef::PendingOperand diff --git a/compiler/rustc_codegen_ssa/src/mir/operand.rs b/compiler/rustc_codegen_ssa/src/mir/operand.rs index f90d1a0fc9c..ef66aa6ce1c 100644 --- a/compiler/rustc_codegen_ssa/src/mir/operand.rs +++ b/compiler/rustc_codegen_ssa/src/mir/operand.rs @@ -50,7 +50,8 @@ pub enum OperandValue { /// from [`ConstMethods::const_poison`]. /// /// An `OperandValue` *must* be this variant for any type for which - /// `is_zst` on its `Layout` returns `true`. + /// `is_zst` on its `Layout` returns `true`. Note however that + /// these values can still require alignment. ZeroSized, } diff --git a/compiler/rustc_codegen_ssa/src/mir/place.rs b/compiler/rustc_codegen_ssa/src/mir/place.rs index e7c3906d977..a9ecbdc5f35 100644 --- a/compiler/rustc_codegen_ssa/src/mir/place.rs +++ b/compiler/rustc_codegen_ssa/src/mir/place.rs @@ -114,7 +114,8 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> { bx.struct_gep(ty, self.llval, 1) } Abi::Scalar(_) | Abi::ScalarPair(..) | Abi::Vector { .. } if field.is_zst() => { - // ZST fields are not included in Scalar, ScalarPair, and Vector layouts, so manually offset the pointer. + // ZST fields (even some that require alignment) are not included in Scalar, + // ScalarPair, and Vector layouts, so manually offset the pointer. bx.gep(bx.cx().type_i8(), self.llval, &[bx.const_usize(offset.bytes())]) } Abi::Scalar(_) | Abi::ScalarPair(..) => { diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs index 07c61df2140..fc8d3389102 100644 --- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs +++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs @@ -1004,6 +1004,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { mir::Rvalue::Aggregate(..) => { let ty = rvalue.ty(self.mir, self.cx.tcx()); let ty = self.monomorphize(ty); + // For ZST this can be `OperandValueKind::ZeroSized`. self.cx.spanned_layout_of(ty, span).is_zst() } } diff --git a/compiler/rustc_const_eval/src/interpret/cast.rs b/compiler/rustc_const_eval/src/interpret/cast.rs index 98e853dc4d9..25c74b98611 100644 --- a/compiler/rustc_const_eval/src/interpret/cast.rs +++ b/compiler/rustc_const_eval/src/interpret/cast.rs @@ -410,21 +410,25 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { self.unsize_into_ptr(src, dest, *s, *c) } (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => { - assert_eq!(def_a, def_b); + assert_eq!(def_a, def_b); // implies same number of fields - // unsizing of generic struct with pointer fields - // Example: `Arc` -> `Arc` - // here we need to increase the size of every &T thin ptr field to a fat ptr + // Unsizing of generic struct with pointer fields, like `Arc` -> `Arc`. + // There can be extra fields as long as they don't change their type or are 1-ZST. + // There might also be no field that actually needs unsizing. + let mut found_cast_field = false; for i in 0..src.layout.fields.count() { let cast_ty_field = cast_ty.field(self, i); - if cast_ty_field.is_zst() { - continue; - } let src_field = self.project_field(src, i)?; let dst_field = self.project_field(dest, i)?; - if src_field.layout.ty == cast_ty_field.ty { + if src_field.layout.is_1zst() && cast_ty_field.is_1zst() { + // Skip 1-ZST fields. + } else if src_field.layout.ty == cast_ty_field.ty { self.copy_op(&src_field, &dst_field, /*allow_transmute*/ false)?; } else { + if found_cast_field { + span_bug!(self.cur_span(), "unsize_into: more than one field to cast"); + } + found_cast_field = true; self.unsize_into(&src_field, cast_ty_field, &dst_field)?; } } diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs index 6e57a56b445..443d3c10871 100644 --- a/compiler/rustc_const_eval/src/interpret/operand.rs +++ b/compiler/rustc_const_eval/src/interpret/operand.rs @@ -239,6 +239,7 @@ impl<'tcx, Prov: Provenance> ImmTy<'tcx, Prov> { // if the entire value is uninit, then so is the field (can happen in ConstProp) (Immediate::Uninit, _) => Immediate::Uninit, // the field contains no information, can be left uninit + // (Scalar/ScalarPair can contain even aligned ZST, not just 1-ZST) _ if layout.is_zst() => Immediate::Uninit, // some fieldless enum variants can have non-zero size but still `Aggregate` ABI... try // to detect those here and also give them no data diff --git a/compiler/rustc_const_eval/src/interpret/terminator.rs b/compiler/rustc_const_eval/src/interpret/terminator.rs index 42a2fb0330c..f3c38e363de 100644 --- a/compiler/rustc_const_eval/src/interpret/terminator.rs +++ b/compiler/rustc_const_eval/src/interpret/terminator.rs @@ -684,15 +684,15 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { } _ => { // Not there yet, search for the only non-ZST field. + // (The rules for `DispatchFromDyn` ensure there's exactly one such field.) let mut non_zst_field = None; for i in 0..receiver.layout.fields.count() { let field = self.project_field(&receiver, i)?; - let zst = - field.layout.is_zst() && field.layout.align.abi.bytes() == 1; + let zst = field.layout.is_1zst(); if !zst { assert!( non_zst_field.is_none(), - "multiple non-ZST fields in dyn receiver type {}", + "multiple non-1-ZST fields in dyn receiver type {}", receiver.layout.ty ); non_zst_field = Some(field); @@ -700,7 +700,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { } receiver = non_zst_field.unwrap_or_else(|| { panic!( - "no non-ZST fields in dyn receiver type {}", + "no non-1-ZST fields in dyn receiver type {}", receiver.layout.ty ) }); -- cgit 1.4.1-3-g733a5