Use zero based indexing for pass_count

Author: oli-obk

compiler/rustc_middle/src/mir/mod.rs

@@ -335,7 +335,7 @@ impl<'tcx> Body<'tcx> {
 
         let mut body = Body {
             phase: MirPhase::Built,
-            pass_count: 1,
+            pass_count: 0,
             source,
             basic_blocks: BasicBlocks::new(basic_blocks),
             source_scopes,
@@ -370,7 +370,7 @@ impl<'tcx> Body<'tcx> {
     pub fn new_cfg_only(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>) -> Self {
         let mut body = Body {
             phase: MirPhase::Built,
-            pass_count: 1,
+            pass_count: 0,
             source: MirSource::item(CRATE_DEF_ID.to_def_id()),
             basic_blocks: BasicBlocks::new(basic_blocks),
             source_scopes: IndexVec::new(),

compiler/rustc_mir_build/src/build/custom/mod.rs

@@ -57,7 +57,7 @@ pub(super) fn build_custom_mir<'tcx>(
         is_polymorphic: false,
         tainted_by_errors: None,
         injection_phase: None,
-        pass_count: 1,
+        pass_count: 0,
     };
 
     body.local_decls.push(LocalDecl::new(return_ty, return_ty_span));

compiler/rustc_mir_transform/src/pass_manager.rs

@@ -140,6 +140,7 @@ fn run_passes_inner<'tcx>(
         }
 
         body.phase = new_phase;
+        body.pass_count = 0;
 
         dump_mir_for_phase_change(tcx, body);
         if validate || new_phase == MirPhase::Runtime(RuntimePhase::Optimized) {
@@ -171,5 +172,6 @@ pub fn dump_mir_for_pass<'tcx>(
 }
 
 pub fn dump_mir_for_phase_change<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) {
+    assert_eq!(body.pass_count, 0);
     mir::dump_mir(tcx, true, body.phase.name(), &"after", body, |_, _| Ok(()))
 }