From 33e73091f8d4299e7f281a7d5da5184bf055c895 Mon Sep 17 00:00:00 2001
From: bjorn3 <bjorn3@users.noreply.github.com>
Date: Sat, 1 Feb 2020 16:47:35 +0100
Subject: [PATCH] Don't mark unwind ebbs as cold

This fixes the code_layout optimization, as it would previously try to
move non-existing ebbs.

Fixes #877
---
 src/base.rs                 | 18 ++++++++----------
 src/optimize/code_layout.rs |  2 --
 2 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/src/base.rs b/src/base.rs
index 6af9ddd8894..5860e3121b4 100644
--- a/src/base.rs
+++ b/src/base.rs
@@ -32,12 +32,6 @@ pub fn trans_fn<'clif, 'tcx, B: Backend + 'static>(
     // Predefine ebb's
     let start_ebb = bcx.create_ebb();
     let ebb_map: IndexVec<BasicBlock, Ebb> = (0..mir.basic_blocks().len()).map(|_| bcx.create_ebb()).collect();
-    let mut cold_ebbs = EntitySet::new();
-    for (bb, &ebb) in ebb_map.iter_enumerated() {
-        if mir.basic_blocks()[bb].is_cleanup {
-            cold_ebbs.insert(ebb);
-        }
-    }
 
     // Make FunctionCx
     let pointer_type = cx.module.target_config().pointer_type();
@@ -55,7 +49,7 @@ pub fn trans_fn<'clif, 'tcx, B: Backend + 'static>(
         ebb_map,
         local_map: HashMap::new(),
         caller_location: None, // set by `codegen_fn_prelude`
-        cold_ebbs,
+        cold_ebbs: EntitySet::new(),
 
         clif_comments,
         constants_cx: &mut cx.constants_cx,
@@ -148,13 +142,17 @@ pub fn verify_func(tcx: TyCtxt, writer: &crate::pretty_clif::CommentWriter, func
 
 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
+        let ebb = fx.get_ebb(bb);
+        fx.bcx.switch_to_block(ebb);
+
         if bb_data.is_cleanup {
             // Unwinding after panicking is not supported
             continue;
-        }
 
-        let ebb = fx.get_ebb(bb);
-        fx.bcx.switch_to_block(ebb);
+            // FIXME once unwinding is supported uncomment next lines
+            // // Unwinding is unlikely to happen, so mark cleanup ebb's as cold.
+            // fx.cold_ebbs.insert(ebb);
+        }
 
         fx.bcx.ins().nop();
         for stmt in &bb_data.statements {
diff --git a/src/optimize/code_layout.rs b/src/optimize/code_layout.rs
index 9ceca814150..4d2301c6f6c 100644
--- a/src/optimize/code_layout.rs
+++ b/src/optimize/code_layout.rs
@@ -11,8 +11,6 @@
 use crate::prelude::*;
 
 pub(super) fn optimize_function(ctx: &mut Context, cold_ebbs: &EntitySet<Ebb>) {
-    return; // FIXME add ebb arguments back
-
     // FIXME Move the ebb in place instead of remove and append once
     // bytecodealliance/cranelift#1339 is implemented.