diff --git a/src/abi/mod.rs b/src/abi/mod.rs
index cde362e18347..b8bf2cf831a1 100644
--- a/src/abi/mod.rs
+++ b/src/abi/mod.rs
@@ -398,7 +398,7 @@ pub fn codegen_fn_prelude(fx: &mut FunctionCx<'_, '_, impl Backend>, start_ebb:
 
     fx.bcx
         .ins()
-        .jump(*fx.ebb_map.get(&START_BLOCK).unwrap(), &[]);
+        .jump(*fx.ebb_map.get(START_BLOCK).unwrap(), &[]);
 }
 
 pub fn codegen_terminator_call<'tcx>(
diff --git a/src/base.rs b/src/base.rs
index 81ca47fe6458..ac18ff6228a5 100644
--- a/src/base.rs
+++ b/src/base.rs
@@ -1,4 +1,5 @@
 use rustc::ty::adjustment::PointerCast;
+use rustc_index::vec::IndexVec;
 
 use crate::prelude::*;
 
@@ -27,10 +28,7 @@ pub fn trans_fn<'clif, 'tcx, B: Backend + 'static>(
 
     // Predefine ebb's
     let start_ebb = bcx.create_ebb();
-    let mut ebb_map: HashMap<BasicBlock, Ebb> = HashMap::new();
-    for (bb, _bb_data) in mir.basic_blocks().iter_enumerated() {
-        ebb_map.insert(bb, bcx.create_ebb());
-    }
+    let ebb_map: IndexVec<BasicBlock, Ebb> = (0..mir.basic_blocks().len()).map(|_| bcx.create_ebb()).collect();
 
     // Make FunctionCx
     let pointer_type = cx.module.target_config().pointer_type();
diff --git a/src/common.rs b/src/common.rs
index b14e8af79a8d..e5b932947ccc 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -1,5 +1,6 @@
 use rustc::ty::layout::{Integer, Primitive};
 use rustc_target::spec::{HasTargetSpec, Target};
+use rustc_index::vec::IndexVec;
 
 use cranelift_codegen::ir::{InstructionData, Opcode, ValueDef};
 
@@ -263,7 +264,7 @@ pub struct FunctionCx<'clif, 'tcx, B: Backend + 'static> {
     pub mir: &'tcx Body<'tcx>,
 
     pub bcx: FunctionBuilder<'clif>,
-    pub ebb_map: HashMap<BasicBlock, Ebb>,
+    pub ebb_map: IndexVec<BasicBlock, Ebb>,
     pub local_map: HashMap<Local, CPlace<'tcx>>,
 
     pub clif_comments: crate::pretty_clif::CommentWriter,
@@ -341,7 +342,7 @@ impl<'tcx, B: Backend + 'static> FunctionCx<'_, 'tcx, B> {
     }
 
     pub fn get_ebb(&self, bb: BasicBlock) -> Ebb {
-        *self.ebb_map.get(&bb).unwrap()
+        *self.ebb_map.get(bb).unwrap()
     }
 
     pub fn get_local_place(&mut self, local: Local) -> CPlace<'tcx> {