From 23cd90ed41b6f1299d51da80cc6481f28a4b0f1f Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Fri, 21 Jul 2017 23:18:34 -0700
Subject: [PATCH] add -Z flag for AddValidation pass

---
 src/librustc/session/config.rs               | 2 ++
 src/librustc_mir/transform/add_validation.rs | 4 ++++
 src/librustc_mir/transform/erase_regions.rs  | 6 ++++++
 3 files changed, 12 insertions(+)

diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 8b55eb4c099a..c5ddcb597cbb 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -1025,6 +1025,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "the directory the MIR is dumped into"),
     dump_mir_exclude_pass_number: bool = (false, parse_bool, [UNTRACKED],
           "if set, exclude the pass number when dumping MIR (used in tests)"),
+    mir_emit_validate: bool = (false, parse_bool, [TRACKED],
+          "emit Validate MIR statements, interpreted e.g. by miri"),
     perf_stats: bool = (false, parse_bool, [UNTRACKED],
           "print some performance-related statistics"),
     hir_stats: bool = (false, parse_bool, [UNTRACKED],
diff --git a/src/librustc_mir/transform/add_validation.rs b/src/librustc_mir/transform/add_validation.rs
index 005d793cd8b5..e400683e8b4e 100644
--- a/src/librustc_mir/transform/add_validation.rs
+++ b/src/librustc_mir/transform/add_validation.rs
@@ -85,6 +85,10 @@ impl MirPass for AddValidation {
                           tcx: TyCtxt<'a, 'tcx, 'tcx>,
                           _: MirSource,
                           mir: &mut Mir<'tcx>) {
+        if !tcx.sess.opts.debugging_opts.mir_emit_validate {
+            return;
+        }
+
         let local_decls = mir.local_decls.clone(); // TODO: Find a way to get rid of this clone.
 
         /// Convert an lvalue to a validation operand.
diff --git a/src/librustc_mir/transform/erase_regions.rs b/src/librustc_mir/transform/erase_regions.rs
index 12b1c549ffec..05376ff3d526 100644
--- a/src/librustc_mir/transform/erase_regions.rs
+++ b/src/librustc_mir/transform/erase_regions.rs
@@ -77,6 +77,12 @@ impl<'a, 'tcx> MutVisitor<'tcx> for EraseRegionsVisitor<'a, 'tcx> {
                        block: BasicBlock,
                        statement: &mut Statement<'tcx>,
                        location: Location) {
+        if !self.tcx.sess.opts.debugging_opts.mir_emit_validate {
+            if let StatementKind::EndRegion(_) = statement.kind {
+                statement.kind = StatementKind::Nop;
+            }
+        }
+
         self.in_validation_statement = match statement.kind {
             StatementKind::Validate(..) => true,
             _ => false,