From 57eb29cd2dc30c47b613ced135422a4120bc6a78 Mon Sep 17 00:00:00 2001 From: Camelid Date: Wed, 16 Sep 2020 15:31:56 -0700 Subject: [PATCH] Update based on review suggestions --- compiler/rustc_middle/src/mir/mod.rs | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs index e6bb746f618..58b69d022d9 100644 --- a/compiler/rustc_middle/src/mir/mod.rs +++ b/compiler/rustc_middle/src/mir/mod.rs @@ -1076,20 +1076,24 @@ pub struct VarDebugInfo<'tcx> { // BasicBlock rustc_index::newtype_index! { - /// The unit of the MIR [control-flow graph][CFG]. + /// A node in the MIR [control-flow graph][CFG]. /// /// There are no branches (e.g., `if`s, function calls, etc.) within a basic block, which makes /// it easier to do [data-flow analyses] and optimizations. Instead, branches are represented /// as an edge in a graph between basic blocks. /// /// Basic blocks consist of a series of [statements][Statement], ending with a - /// [terminator][Terminator]. Basic blocks can have multiple predecessors and successors. + /// [terminator][Terminator]. Basic blocks can have multiple predecessors and successors, + /// however there is a MIR pass ([`CriticalCallEdges`]) that removes *critical edges*, which + /// are edges that go from a multi-successor node to a multi-predecessor node. This pass is + /// needed because some analyses require that there are no critical edges in the CFG. /// /// Read more about basic blocks in the [rustc-dev-guide][guide-mir]. /// /// [CFG]: https://rustc-dev-guide.rust-lang.org/appendix/background.html#cfg /// [data-flow analyses]: /// https://rustc-dev-guide.rust-lang.org/appendix/background.html#what-is-a-dataflow-analysis + /// [`CriticalCallEdges`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir/transform/add_call_guards/enum.AddCallGuards.html#variant.CriticalCallEdges /// [guide-mir]: https://rustc-dev-guide.rust-lang.org/mir/ pub struct BasicBlock { derive [HashStable]