From 4e4092f8ccb4b7f8b3c4a5cdcbfcdfafa8f5f1e1 Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Wed, 19 Oct 2022 10:34:45 +1100 Subject: [PATCH 1/5] rustc_codegen_ssa: use more consistent naming. Ensure: - builders always have a `bx` suffix; - backend basic blocks always have an `llbb` suffix, - paired builders and basic blocks have consistent prefixes. --- compiler/rustc_codegen_ssa/src/mir/block.rs | 41 +++++++++++---------- compiler/rustc_codegen_ssa/src/mir/mod.rs | 20 +++++----- 2 files changed, 31 insertions(+), 30 deletions(-) diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs index bd4f0cac7eb46..e7abae665e357 100644 --- a/compiler/rustc_codegen_ssa/src/mir/block.rs +++ b/compiler/rustc_codegen_ssa/src/mir/block.rs @@ -95,10 +95,10 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> { debug!("llblock: creating cleanup trampoline for {:?}", target); let name = &format!("{:?}_cleanup_trampoline_{:?}", self.bb, target); - let trampoline = Bx::append_block(fx.cx, fx.llfn, name); - let mut trampoline_bx = Bx::build(fx.cx, trampoline); + let trampoline_llbb = Bx::append_block(fx.cx, fx.llfn, name); + let mut trampoline_bx = Bx::build(fx.cx, trampoline_llbb); trampoline_bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget)); - trampoline + trampoline_llbb } else { lltarget } @@ -1459,20 +1459,20 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { // bar(); // } Some(&mir::TerminatorKind::Abort) => { - let cs_bb = + let cs_llbb = Bx::append_block(self.cx, self.llfn, &format!("cs_funclet{:?}", bb)); - let cp_bb = + let cp_llbb = Bx::append_block(self.cx, self.llfn, &format!("cp_funclet{:?}", bb)); - ret_llbb = cs_bb; + ret_llbb = cs_llbb; - let mut cs_bx = Bx::build(self.cx, cs_bb); - let cs = cs_bx.catch_switch(None, None, &[cp_bb]); + let mut cs_bx = Bx::build(self.cx, cs_llbb); + let cs = cs_bx.catch_switch(None, None, &[cp_llbb]); // The "null" here is actually a RTTI type descriptor for the // C++ personality function, but `catch (...)` has no type so // it's null. The 64 here is actually a bitfield which // represents that this is a catch-all block. - let mut cp_bx = Bx::build(self.cx, cp_bb); + let mut cp_bx = Bx::build(self.cx, cp_llbb); let null = cp_bx.const_null( cp_bx.type_i8p_ext(cp_bx.cx().data_layout().instruction_address_space), ); @@ -1481,10 +1481,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { cp_bx.br(llbb); } _ => { - let cleanup_bb = + let cleanup_llbb = Bx::append_block(self.cx, self.llfn, &format!("funclet_{:?}", bb)); - ret_llbb = cleanup_bb; - let mut cleanup_bx = Bx::build(self.cx, cleanup_bb); + ret_llbb = cleanup_llbb; + let mut cleanup_bx = Bx::build(self.cx, cleanup_llbb); funclet = cleanup_bx.cleanup_pad(None, &[]); cleanup_bx.br(llbb); } @@ -1492,19 +1492,20 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { self.funclets[bb] = Some(funclet); ret_llbb } else { - let bb = Bx::append_block(self.cx, self.llfn, "cleanup"); - let mut bx = Bx::build(self.cx, bb); + let cleanup_llbb = Bx::append_block(self.cx, self.llfn, "cleanup"); + let mut cleanup_bx = Bx::build(self.cx, cleanup_llbb); let llpersonality = self.cx.eh_personality(); let llretty = self.landing_pad_type(); - let lp = bx.cleanup_landing_pad(llretty, llpersonality); + let lp = cleanup_bx.cleanup_landing_pad(llretty, llpersonality); - let slot = self.get_personality_slot(&mut bx); - slot.storage_live(&mut bx); - Pair(bx.extract_value(lp, 0), bx.extract_value(lp, 1)).store(&mut bx, slot); + let slot = self.get_personality_slot(&mut cleanup_bx); + slot.storage_live(&mut cleanup_bx); + Pair(cleanup_bx.extract_value(lp, 0), cleanup_bx.extract_value(lp, 1)) + .store(&mut cleanup_bx, slot); - bx.br(llbb); - bx.llbb() + cleanup_bx.br(llbb); + cleanup_llbb } } diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs index 2b931bfc91d63..da9aaf00ecf6e 100644 --- a/compiler/rustc_codegen_ssa/src/mir/mod.rs +++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs @@ -148,10 +148,10 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( let debug_context = cx.create_function_debug_context(instance, &fn_abi, llfn, &mir); let start_llbb = Bx::append_block(cx, llfn, "start"); - let mut bx = Bx::build(cx, start_llbb); + let mut start_bx = Bx::build(cx, start_llbb); if mir.basic_blocks.iter().any(|bb| bb.is_cleanup) { - bx.set_personality_fn(cx.eh_personality()); + start_bx.set_personality_fn(cx.eh_personality()); } let cleanup_kinds = analyze::cleanup_kinds(&mir); @@ -180,7 +180,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( caller_location: None, }; - fx.per_local_var_debug_info = fx.compute_per_local_var_debug_info(&mut bx); + fx.per_local_var_debug_info = fx.compute_per_local_var_debug_info(&mut start_bx); // Evaluate all required consts; codegen later assumes that CTFE will never fail. let mut all_consts_ok = true; @@ -206,29 +206,29 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( // Allocate variable and temp allocas fx.locals = { - let args = arg_local_refs(&mut bx, &mut fx, &memory_locals); + let args = arg_local_refs(&mut start_bx, &mut fx, &memory_locals); let mut allocate_local = |local| { let decl = &mir.local_decls[local]; - let layout = bx.layout_of(fx.monomorphize(decl.ty)); + let layout = start_bx.layout_of(fx.monomorphize(decl.ty)); assert!(!layout.ty.has_erasable_regions()); if local == mir::RETURN_PLACE && fx.fn_abi.ret.is_indirect() { debug!("alloc: {:?} (return place) -> place", local); - let llretptr = bx.get_param(0); + let llretptr = start_bx.get_param(0); return LocalRef::Place(PlaceRef::new_sized(llretptr, layout)); } if memory_locals.contains(local) { debug!("alloc: {:?} -> place", local); if layout.is_unsized() { - LocalRef::UnsizedPlace(PlaceRef::alloca_unsized_indirect(&mut bx, layout)) + LocalRef::UnsizedPlace(PlaceRef::alloca_unsized_indirect(&mut start_bx, layout)) } else { - LocalRef::Place(PlaceRef::alloca(&mut bx, layout)) + LocalRef::Place(PlaceRef::alloca(&mut start_bx, layout)) } } else { debug!("alloc: {:?} -> operand", local); - LocalRef::new_operand(&mut bx, layout) + LocalRef::new_operand(&mut start_bx, layout) } }; @@ -240,7 +240,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( }; // Apply debuginfo to the newly allocated locals. - fx.debug_introduce_locals(&mut bx); + fx.debug_introduce_locals(&mut start_bx); // Codegen the body of each block using reverse postorder for (bb, _) in traversal::reverse_postorder(&mir) { From a5bd5da59479e1581b9cb76d3d05a9b85c9b02fc Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Wed, 19 Oct 2022 10:53:38 +1100 Subject: [PATCH 2/5] Rename two `TerminatorCodegenHelper` methods. `TerminatorCodegenHelper` has three methods `llblock`, `llbb`, and `lltarget`. They're all similar, but the names given no indication of the differences. This commit renames `lltarget` as `llbb_with_landing_pad`, and `llblock` as `llbb_with_cleanup`. These aren't fantastic names, but at least it's now clear that `llbb` is the lowest-level of the three and the other two wrap it. --- compiler/rustc_codegen_ssa/src/mir/block.rs | 29 ++++++++++++--------- 1 file changed, 16 insertions(+), 13 deletions(-) diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs index e7abae665e357..63fafeeefda62 100644 --- a/compiler/rustc_codegen_ssa/src/mir/block.rs +++ b/compiler/rustc_codegen_ssa/src/mir/block.rs @@ -63,7 +63,9 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> { } } - fn lltarget>( + /// Get a basic block (creating it if necessary), possibly with a landing + /// pad next to it. + fn llbb_with_landing_pad>( &self, fx: &mut FunctionCx<'a, 'tcx, Bx>, target: mir::BasicBlock, @@ -83,17 +85,18 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> { } } - /// Create a basic block. - fn llblock>( + /// Get a basic block (creating it if necessary), possibly with cleanup + /// stuff in it or next to it. + fn llbb_with_cleanup>( &self, fx: &mut FunctionCx<'a, 'tcx, Bx>, target: mir::BasicBlock, ) -> Bx::BasicBlock { - let (lltarget, is_cleanupret) = self.lltarget(fx, target); + let (lltarget, is_cleanupret) = self.llbb_with_landing_pad(fx, target); if is_cleanupret { // MSVC cross-funclet jump - need a trampoline - debug!("llblock: creating cleanup trampoline for {:?}", target); + 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); let mut trampoline_bx = Bx::build(fx.cx, trampoline_llbb); @@ -110,7 +113,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> { bx: &mut Bx, target: mir::BasicBlock, ) { - let (lltarget, is_cleanupret) = self.lltarget(fx, target); + let (lltarget, is_cleanupret) = self.llbb_with_landing_pad(fx, target); if is_cleanupret { // micro-optimization: generate a `ret` rather than a jump // to a trampoline. @@ -138,7 +141,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> { let fn_ty = bx.fn_decl_backend_type(&fn_abi); let unwind_block = if let Some(cleanup) = cleanup.filter(|_| fn_abi.can_unwind) { - Some(self.llblock(fx, cleanup)) + Some(self.llbb_with_cleanup(fx, cleanup)) } else if fx.mir[self.bb].is_cleanup && fn_abi.can_unwind && !base::wants_msvc_seh(fx.cx.tcx().sess) @@ -231,7 +234,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> { options, line_spans, instance, - Some((ret_llbb, self.llblock(fx, cleanup), self.funclet(fx))), + Some((ret_llbb, self.llbb_with_cleanup(fx, cleanup), self.funclet(fx))), ); } else { bx.codegen_inline_asm(template, &operands, options, line_spans, instance, None); @@ -281,8 +284,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { if target_iter.len() == 1 { // If there are two targets (one conditional, one fallback), emit br instead of switch let (test_value, target) = target_iter.next().unwrap(); - let lltrue = helper.llblock(self, target); - let llfalse = helper.llblock(self, targets.otherwise()); + let lltrue = helper.llbb_with_cleanup(self, target); + let llfalse = helper.llbb_with_cleanup(self, targets.otherwise()); if switch_ty == bx.tcx().types.bool { // Don't generate trivial icmps when switching on bool match test_value { @@ -299,8 +302,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { } else { bx.switch( discr.immediate(), - helper.llblock(self, targets.otherwise()), - target_iter.map(|(value, target)| (value, helper.llblock(self, target))), + helper.llbb_with_cleanup(self, targets.otherwise()), + target_iter.map(|(value, target)| (value, helper.llbb_with_cleanup(self, target))), ); } } @@ -530,7 +533,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { let cond = bx.expect(cond, expected); // Create the failure block and the conditional branch to it. - let lltarget = helper.llblock(self, target); + let lltarget = helper.llbb_with_cleanup(self, target); let panic_block = bx.append_sibling_block("panic"); if expected { bx.cond_br(cond, lltarget, panic_block); From 03f350f5a5464e19484ab17f6a745c48d98d3415 Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Wed, 19 Oct 2022 10:59:02 +1100 Subject: [PATCH 3/5] Clarify some cleanup stuff. - Rearrange the match in `llbb_with_landing_pad` so the `(Some,Some)` cases are together. - Add assertions to indicate two MSVC-only paths. --- compiler/rustc_codegen_ssa/src/mir/block.rs | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs index 63fafeeefda62..29b7c9b0a8832 100644 --- a/compiler/rustc_codegen_ssa/src/mir/block.rs +++ b/compiler/rustc_codegen_ssa/src/mir/block.rs @@ -75,13 +75,16 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> { let target_funclet = fx.cleanup_kinds[target].funclet_bb(target); match (self.funclet_bb, target_funclet) { (None, None) => (lltarget, false), - (Some(f), Some(t_f)) if f == t_f || !base::wants_msvc_seh(fx.cx.tcx().sess) => { - (lltarget, false) - } // jump *into* cleanup - need a landing pad if GNU, cleanup pad if MSVC (None, Some(_)) => (fx.landing_pad_for(target), false), (Some(_), None) => span_bug!(span, "{:?} - jump out of cleanup?", self.terminator), - (Some(_), Some(_)) => (fx.landing_pad_for(target), true), + (Some(f), Some(t_f)) => { + if f == t_f || !base::wants_msvc_seh(fx.cx.tcx().sess) { + (lltarget, false) + } else { + (fx.landing_pad_for(target), true) + } + } } } @@ -95,7 +98,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> { let (lltarget, is_cleanupret) = self.llbb_with_landing_pad(fx, target); if is_cleanupret { // MSVC cross-funclet jump - need a trampoline - + debug_assert!(base::wants_msvc_seh(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); @@ -115,8 +118,9 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> { ) { let (lltarget, is_cleanupret) = self.llbb_with_landing_pad(fx, target); if is_cleanupret { - // micro-optimization: generate a `ret` rather than a jump + // MSVC micro-optimization: generate a `ret` rather than a jump // to a trampoline. + debug_assert!(base::wants_msvc_seh(fx.cx.tcx().sess)); bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget)); } else { bx.br(lltarget); From 8c02f4d05d8840e387a97faad577187e80d3da88 Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Tue, 25 Oct 2022 13:51:52 +1100 Subject: [PATCH 4/5] Inline and remove `cast_shift_rhs`. It has a single call site. --- compiler/rustc_codegen_ssa/src/base.rs | 9 --------- 1 file changed, 9 deletions(-) diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs index ff1eee37ad9c0..09f803ad88fc4 100644 --- a/compiler/rustc_codegen_ssa/src/base.rs +++ b/compiler/rustc_codegen_ssa/src/base.rs @@ -340,15 +340,6 @@ pub fn cast_shift_expr_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( op: hir::BinOpKind, lhs: Bx::Value, rhs: Bx::Value, -) -> Bx::Value { - cast_shift_rhs(bx, op, lhs, rhs) -} - -fn cast_shift_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( - bx: &mut Bx, - op: hir::BinOpKind, - lhs: Bx::Value, - rhs: Bx::Value, ) -> Bx::Value { // Shifts may have any size int on the rhs if op.is_shift() { From 6cd35ac2035327339d2428ff0be695ed5d5681dc Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Tue, 25 Oct 2022 14:39:20 +1100 Subject: [PATCH 5/5] Simplify `cast_shift_expr_rhs`. It's only ever used with shift operators. --- compiler/rustc_codegen_ssa/src/base.rs | 37 ++++++++++-------------- compiler/rustc_codegen_ssa/src/common.rs | 5 ++-- 2 files changed, 18 insertions(+), 24 deletions(-) diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs index 09f803ad88fc4..84b89cd71a6d3 100644 --- a/compiler/rustc_codegen_ssa/src/base.rs +++ b/compiler/rustc_codegen_ssa/src/base.rs @@ -337,31 +337,26 @@ pub fn coerce_unsized_into<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( pub fn cast_shift_expr_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx: &mut Bx, - op: hir::BinOpKind, lhs: Bx::Value, rhs: Bx::Value, ) -> Bx::Value { // Shifts may have any size int on the rhs - if op.is_shift() { - let mut rhs_llty = bx.cx().val_ty(rhs); - let mut lhs_llty = bx.cx().val_ty(lhs); - if bx.cx().type_kind(rhs_llty) == TypeKind::Vector { - rhs_llty = bx.cx().element_type(rhs_llty) - } - if bx.cx().type_kind(lhs_llty) == TypeKind::Vector { - lhs_llty = bx.cx().element_type(lhs_llty) - } - let rhs_sz = bx.cx().int_width(rhs_llty); - let lhs_sz = bx.cx().int_width(lhs_llty); - if lhs_sz < rhs_sz { - bx.trunc(rhs, lhs_llty) - } else if lhs_sz > rhs_sz { - // FIXME (#1877: If in the future shifting by negative - // values is no longer undefined then this is wrong. - bx.zext(rhs, lhs_llty) - } else { - rhs - } + let mut rhs_llty = bx.cx().val_ty(rhs); + let mut lhs_llty = bx.cx().val_ty(lhs); + if bx.cx().type_kind(rhs_llty) == TypeKind::Vector { + rhs_llty = bx.cx().element_type(rhs_llty) + } + if bx.cx().type_kind(lhs_llty) == TypeKind::Vector { + lhs_llty = bx.cx().element_type(lhs_llty) + } + let rhs_sz = bx.cx().int_width(rhs_llty); + let lhs_sz = bx.cx().int_width(lhs_llty); + if lhs_sz < rhs_sz { + bx.trunc(rhs, lhs_llty) + } else if lhs_sz > rhs_sz { + // FIXME (#1877: If in the future shifting by negative + // values is no longer undefined then this is wrong. + bx.zext(rhs, lhs_llty) } else { rhs } diff --git a/compiler/rustc_codegen_ssa/src/common.rs b/compiler/rustc_codegen_ssa/src/common.rs index 8ca1a6084cf6f..71f9179d02cca 100644 --- a/compiler/rustc_codegen_ssa/src/common.rs +++ b/compiler/rustc_codegen_ssa/src/common.rs @@ -1,7 +1,6 @@ #![allow(non_camel_case_types)] use rustc_errors::struct_span_err; -use rustc_hir as hir; use rustc_hir::LangItem; use rustc_middle::mir::interpret::ConstValue; use rustc_middle::ty::{self, layout::TyAndLayout, Ty, TyCtxt}; @@ -140,7 +139,7 @@ pub fn build_unchecked_lshift<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( lhs: Bx::Value, rhs: Bx::Value, ) -> Bx::Value { - let rhs = base::cast_shift_expr_rhs(bx, hir::BinOpKind::Shl, lhs, rhs); + let rhs = base::cast_shift_expr_rhs(bx, lhs, rhs); // #1877, #10183: Ensure that input is always valid let rhs = shift_mask_rhs(bx, rhs); bx.shl(lhs, rhs) @@ -152,7 +151,7 @@ pub fn build_unchecked_rshift<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( lhs: Bx::Value, rhs: Bx::Value, ) -> Bx::Value { - let rhs = base::cast_shift_expr_rhs(bx, hir::BinOpKind::Shr, lhs, rhs); + let rhs = base::cast_shift_expr_rhs(bx, lhs, rhs); // #1877, #10183: Ensure that input is always valid let rhs = shift_mask_rhs(bx, rhs); let is_signed = lhs_t.is_signed();