From 24e03341af566cde6c368241ff36e91ac539a374 Mon Sep 17 00:00:00 2001
From: Wolfgang Pieb <Wolfgang.Pieb@sony.com>
Date: Thu, 21 Jul 2016 23:28:18 +0000
Subject: [PATCH] Reverting r275115 which caused PR28634. When empty
 (forwarding) basic blocks that are referenced by user labels are removed,
 incorrect code may be generated.

llvm-svn: 276361
---
 clang/lib/CodeGen/CGStmt.cpp              | 14 +--------
 clang/test/CodeGen/forwarding-blocks-if.c | 36 -----------------------
 2 files changed, 1 insertion(+), 49 deletions(-)
 delete mode 100644 clang/test/CodeGen/forwarding-blocks-if.c

diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index 31f19829d920..2adb1770ea47 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -623,14 +623,7 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
     RunCleanupsScope ThenScope(*this);
     EmitStmt(S.getThen());
   }
-  {
-    auto CurBlock = Builder.GetInsertBlock();
-    EmitBranch(ContBlock);
-    // Eliminate any empty blocks that may have been created by nested
-    // control flow statements in the 'then' clause.
-    if (CurBlock)
-      SimplifyForwardingBlocks(CurBlock); 
-  }
+  EmitBranch(ContBlock);
 
   // Emit the 'else' code if present.
   if (const Stmt *Else = S.getElse()) {
@@ -646,12 +639,7 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
     {
       // There is no need to emit line number for an unconditional branch.
       auto NL = ApplyDebugLocation::CreateEmpty(*this);
-      auto CurBlock = Builder.GetInsertBlock();
       EmitBranch(ContBlock);
-      // Eliminate any empty blocks that may have been created by nested
-      // control flow statements emitted in the 'else' clause.
-      if (CurBlock)
-        SimplifyForwardingBlocks(CurBlock); 
     }
   }
 
diff --git a/clang/test/CodeGen/forwarding-blocks-if.c b/clang/test/CodeGen/forwarding-blocks-if.c
deleted file mode 100644
index 51711bf0ef46..000000000000
--- a/clang/test/CodeGen/forwarding-blocks-if.c
+++ /dev/null
@@ -1,36 +0,0 @@
-// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s
-// Check that no empty blocks are generated for nested ifs.
-
-extern void func();
-
-int f0(int val) {
-  if (val == 0) {
-    func();
-  } else if (val == 1) {
-    func();
-  }
-  return 0;
-}
-
-// CHECK-LABEL: define {{.*}}i32 @f0
-// CHECK: call void {{.*}} @func
-// CHECK: call void {{.*}} @func
-// CHECK: br label %[[RETBLOCK1:[^ ]*]]
-// CHECK: [[RETBLOCK1]]:
-// CHECK-NOT: br label
-// CHECK: ret i32
-
-int f1(int val, int g) {
-  if (val == 0)
-    if (g == 1) {
-      func();
-    }
-  return 0;
-}
-
-// CHECK-LABEL: define {{.*}}i32 @f1
-// CHECK: call void {{.*}} @func
-// CHECK: br label %[[RETBLOCK2:[^ ]*]]
-// CHECK: [[RETBLOCK2]]:
-// CHECK-NOT: br label
-// CHECK: ret i32