[OPT] Use IndexVec instead of HashMap in ssa analysis

Author: bjorn3

src/abi/mod.rs

@@ -347,7 +347,7 @@ pub fn codegen_fn_prelude(fx: &mut FunctionCx<'_, '_, impl Backend>, start_ebb:
     for (local, arg_kind, ty) in func_params {
         let layout = fx.layout_of(ty);
 
-        let is_ssa = *ssa_analyzed.get(&local).unwrap() == crate::analyze::SsaKind::Ssa;
+        let is_ssa = ssa_analyzed[local] == crate::analyze::SsaKind::Ssa;
 
         match arg_kind {
             ArgKind::Normal(Some(val)) => {
@@ -401,7 +401,7 @@ pub fn codegen_fn_prelude(fx: &mut FunctionCx<'_, '_, impl Backend>, start_ebb:
         let ty = fx.monomorphize(&fx.mir.local_decls[local].ty);
         let layout = fx.layout_of(ty);
 
-        let is_ssa = *ssa_analyzed.get(&local).unwrap() == crate::analyze::SsaKind::Ssa;
+        let is_ssa = ssa_analyzed[local] == crate::analyze::SsaKind::Ssa;
 
         local_place(fx, local, layout, is_ssa);
     }

src/abi/returning.rs

@@ -3,7 +3,7 @@ use crate::prelude::*;
 
 pub fn codegen_return_param(
     fx: &mut FunctionCx<impl Backend>,
-    ssa_analyzed: &HashMap<Local, crate::analyze::SsaKind>,
+    ssa_analyzed: &rustc_index::vec::IndexVec<Local, crate::analyze::SsaKind>,
     start_ebb: Ebb,
 ) {
     let ret_layout = fx.return_layout();
@@ -16,8 +16,7 @@ pub fn codegen_return_param(
             Empty
         }
         PassMode::ByVal(_) | PassMode::ByValPair(_, _) => {
-            let is_ssa =
-                *ssa_analyzed.get(&RETURN_PLACE).unwrap() == crate::analyze::SsaKind::Ssa;
+            let is_ssa = ssa_analyzed[RETURN_PLACE] == crate::analyze::SsaKind::Ssa;
 
             super::local_place(fx, RETURN_PLACE, ret_layout, is_ssa);
 

src/analyze.rs

@@ -1,23 +1,22 @@
 use crate::prelude::*;
 
 use rustc::mir::StatementKind::*;
+use rustc_index::vec::IndexVec;
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub enum SsaKind {
     NotSsa,
     Ssa,
 }
 
-pub fn analyze(fx: &FunctionCx<'_, '_, impl Backend>) -> HashMap<Local, SsaKind> {
-    let mut flag_map = HashMap::new();
-
-    for (local, local_decl) in fx.mir.local_decls.iter_enumerated() {
+pub fn analyze(fx: &FunctionCx<'_, '_, impl Backend>) -> IndexVec<Local, SsaKind> {
+    let mut flag_map = fx.mir.local_decls.iter().map(|local_decl| {
         if fx.clif_type(local_decl.ty).is_some() {
-            flag_map.insert(local, SsaKind::Ssa);
+            SsaKind::Ssa
         } else {
-            flag_map.insert(local, SsaKind::NotSsa);
+            SsaKind::NotSsa
         }
-    }
+    }).collect::<IndexVec<Local, SsaKind>>();
 
     for bb in fx.mir.basic_blocks().iter() {
         for stmt in bb.statements.iter() {
@@ -44,13 +43,13 @@ pub fn analyze(fx: &FunctionCx<'_, '_, impl Backend>) -> HashMap<Local, SsaKind>
     flag_map
 }
 
-fn analyze_non_ssa_place(flag_map: &mut HashMap<Local, SsaKind>, place: &Place) {
+fn analyze_non_ssa_place(flag_map: &mut IndexVec<Local, SsaKind>, place: &Place) {
     match place.base {
         PlaceBase::Local(local) => not_ssa(flag_map, local),
         _ => {}
     }
 }
 
-fn not_ssa<L: ::std::borrow::Borrow<Local>>(flag_map: &mut HashMap<Local, SsaKind>, local: L) {
-    *flag_map.get_mut(local.borrow()).unwrap() = SsaKind::NotSsa;
+fn not_ssa(flag_map: &mut IndexVec<Local, SsaKind>, local: Local) {
+    flag_map[local] = SsaKind::NotSsa;
 }