DataFlowSanitizer: Remove unreachable BBs so IR continues to verify

under the args ABI.

Differential Revision: http://llvm-reviews.chandlerc.com/D1316

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188113 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Instrumentation/DataFlowSanitizer.cpp

@@ -59,6 +59,7 @@
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Transforms/Utils/SpecialCaseList.h"
 #include <iterator>
 
@@ -402,6 +403,8 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
     if ((*i)->isDeclaration())
       continue;
 
+    removeUnreachableBlocks(**i);
+
     DFSanFunction DFSF(*this, *i);
 
     // DFSanVisitor may create new basic blocks, which confuses df_iterator.

test/Instrumentation/DataFlowSanitizer/args-unreachable-bb.ll

@@ -0,0 +1,20 @@
+; RUN: opt < %s -dfsan -verify -dfsan-args-abi -S | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
+define i8 @unreachable_bb() {
+  ; CHECK: @unreachable_bb
+  ; CHECK: ret { i8, i16 } { i8 1, i16 0 }
+  ; CHECK-NOT: bb2:
+  ; CHECK-NOT: bb3:
+  ; CHECK-NOT: bb4:
+  ret i8 1
+
+bb2:
+  ret i8 2
+
+bb3:
+  br label %bb4
+
+bb4:
+  br label %bb3
+}