New upstream version 1.41.1+dfsg1

[rustc.git] / src / librustc_mir / transform / add_call_guards.rs

diff --git a/src/librustc_mir/transform/add_call_guards.rs b/src/librustc_mir/transform/add_call_guards.rs
index 80b17c6a008f5902334915c89c4677e99d6c0f82..d1832ebf962a486a255e950338a0fd809129fd74 100644 (file)
--- a/src/librustc_mir/transform/add_call_guards.rs
+++ b/src/librustc_mir/transform/add_call_guards.rs
@@ -1,19 +1,14 @@
-// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
 use rustc::ty::TyCtxt;
 use rustc::mir::*;
-use rustc::mir::transform::{MirPass, MirSource, Pass};
-use rustc_data_structures::indexed_vec::{Idx, IndexVec};
+use rustc_index::vec::{Idx, IndexVec};
+use crate::transform::{MirPass, MirSource};
 
-pub struct AddCallGuards;
+#[derive(PartialEq)]
+pub enum AddCallGuards {
+    AllCallEdges,
+    CriticalCallEdges,
+}
+pub use self::AddCallGuards::*;
 
 /**
  * Breaks outgoing critical edges for call terminators in the MIR.
@@ -25,7 +20,7 @@ pub struct AddCallGuards;
  * do at the end of the predecessor block, or at the start of the
  * successor block. Critical edges have to be broken in order to prevent
  * "edge actions" from affecting other edges. We need this for calls that are
- * translated to LLVM invoke instructions, because invoke is a block terminator
+ * codegened to LLVM invoke instructions, because invoke is a block terminator
  * in LLVM so we can't insert any code to handle the call's result into the
  * block that performs the call.
  *
@@ -36,51 +31,54 @@ pub struct AddCallGuards;
  */
 
 impl<'tcx> MirPass<'tcx> for AddCallGuards {
-    fn run_pass<'a>(&mut self, _tcx: TyCtxt<'a, 'tcx, 'tcx>, _src: MirSource, mir: &mut Mir<'tcx>) {
-        add_call_guards(mir);
+    fn run_pass(
+        &self, _tcx: TyCtxt<'tcx>, _src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>
+    ) {
+        self.add_call_guards(body);
     }
 }
 
-pub fn add_call_guards(mir: &mut Mir) {
-    let pred_count: IndexVec<_, _> =
-        mir.predecessors().iter().map(|ps| ps.len()).collect();
+impl AddCallGuards {
+    pub fn add_call_guards(&self, body: &mut BodyAndCache<'_>) {
+        let pred_count: IndexVec<_, _> = body.predecessors().iter().map(|ps| ps.len()).collect();
 
-    // We need a place to store the new blocks generated
-    let mut new_blocks = Vec::new();
+        // We need a place to store the new blocks generated
+        let mut new_blocks = Vec::new();
 
-    let cur_len = mir.basic_blocks().len();
+        let cur_len = body.basic_blocks().len();
 
-    for block in mir.basic_blocks_mut() {
-        match block.terminator {
-            Some(Terminator {
-                kind: TerminatorKind::Call {
-                    destination: Some((_, ref mut destination)),
-                    cleanup: Some(_),
-                    ..
-                }, source_info
-            }) if pred_count[*destination] > 1 => {
-                // It's a critical edge, break it
-                let call_guard = BasicBlockData {
-                    statements: vec![],
-                    is_cleanup: block.is_cleanup,
-                    terminator: Some(Terminator {
-                        source_info: source_info,
-                        kind: TerminatorKind::Goto { target: *destination }
-                    })
-                };
+        for block in body.basic_blocks_mut() {
+            match block.terminator {
+                Some(Terminator {
+                    kind: TerminatorKind::Call {
+                        destination: Some((_, ref mut destination)),
+                        cleanup,
+                        ..
+                    }, source_info
+                }) if pred_count[*destination] > 1 &&
+                      (cleanup.is_some() || self == &AllCallEdges) =>
+                {
+                    // It's a critical edge, break it
+                    let call_guard = BasicBlockData {
+                        statements: vec![],
+                        is_cleanup: block.is_cleanup,
+                        terminator: Some(Terminator {
+                            source_info,
+                            kind: TerminatorKind::Goto { target: *destination }
+                        })
+                    };
 
-                // Get the index it will be when inserted into the MIR
-                let idx = cur_len + new_blocks.len();
-                new_blocks.push(call_guard);
-                *destination = BasicBlock::new(idx);
+                    // Get the index it will be when inserted into the MIR
+                    let idx = cur_len + new_blocks.len();
+                    new_blocks.push(call_guard);
+                    *destination = BasicBlock::new(idx);
+                }
+                _ => {}
             }
-            _ => {}
         }
-    }
 
-    debug!("Broke {} N edges", new_blocks.len());
+        debug!("Broke {} N edges", new_blocks.len());
 
-    mir.basic_blocks_mut().extend(new_blocks);
+        body.basic_blocks_mut().extend(new_blocks);
+    }
 }
-
-impl Pass for AddCallGuards {}