From 157585887eb4e1cafe9c79505da336d2c08b2033 Mon Sep 17 00:00:00 2001
From: MerryMage <MerryMage@users.noreply.github.com>
Date: Sun, 19 Feb 2017 11:04:31 +0000
Subject: [PATCH] ir_opt: Simplify dead-code elimination pass

---
 src/ir_opt/dead_code_elimination_pass.cpp | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/src/ir_opt/dead_code_elimination_pass.cpp b/src/ir_opt/dead_code_elimination_pass.cpp
index 7a65bdc3..c64eb7bb 100644
--- a/src/ir_opt/dead_code_elimination_pass.cpp
+++ b/src/ir_opt/dead_code_elimination_pass.cpp
@@ -4,6 +4,7 @@
  * General Public License version 2 or any later version.
  */
 
+#include "common/iterator_util.h"
 #include "frontend/ir/basic_block.h"
 #include "ir_opt/passes.h"
 
@@ -13,19 +14,11 @@ namespace Optimization {
 void DeadCodeElimination(IR::Block& block) {
     // We iterate over the instructions in reverse order.
     // This is because removing an instruction reduces the number of uses for earlier instructions.
-
-    if (block.empty()) {
-        return;
-    }
-
-    auto iter = block.end();
-    do {
-        --iter;
-        if (!iter->HasUses() && !iter->MayHaveSideEffects()) {
-            iter->Invalidate();
-            iter = block.Instructions().erase(iter);
+    for (auto& inst : Common::Reverse(block)) {
+        if (!inst.HasUses() && !inst.MayHaveSideEffects()) {
+            inst.Invalidate();
         }
-    } while (iter != block.begin());
+    }
 }
 
 } // namespace Optimization