[sancov] Leave llvm.localescape in the entry block

Summary: Similar to the change we applied to ASan. The same test case works.

Reviewers: samsonov

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D11961

llvm-svn: 245067

1 files changed, 36 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/Instrumentation.cpp b/llvm/lib/Transforms/Instrumentation/Instrumentation.cpp
index 2750585..68aee22 100644
--- a/llvm/lib/Transforms/Instrumentation/Instrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/Instrumentation.cpp
@@ -12,12 +12,47 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/InitializePasses.h"
+#include "llvm/Transforms/Instrumentation.h"
 #include "llvm-c/Initialization.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/InitializePasses.h"
 #include "llvm/PassRegistry.h"
 
 using namespace llvm;
 
+/// Moves I before IP. Returns new insert point.
+static BasicBlock::iterator moveBeforeInsertPoint(BasicBlock::iterator I, BasicBlock::iterator IP) {
+  // If I is IP, move the insert point down.
+  if (I == IP)
+    return ++IP;
+  // Otherwise, move I before IP and return IP.
+  I->moveBefore(IP);
+  return IP;
+}
+
+/// Instrumentation passes often insert conditional checks into entry blocks.
+/// Call this function before splitting the entry block to move instructions
+/// that must remain in the entry block up before the split point. Static
+/// allocas and llvm.localescape calls, for example, must remain in the entry
+/// block.
+BasicBlock::iterator llvm::PrepareToSplitEntryBlock(BasicBlock &BB,
+                                                    BasicBlock::iterator IP) {
+  assert(&BB.getParent()->getEntryBlock() == &BB);
+  for (auto I = IP, E = BB.end(); I != E; ++I) {
+    bool KeepInEntry = false;
+    if (auto *AI = dyn_cast<AllocaInst>(I)) {
+      if (AI->isStaticAlloca())
+        KeepInEntry = true;
+    } else if (auto *II = dyn_cast<IntrinsicInst>(I)) {
+      if (II->getIntrinsicID() == llvm::Intrinsic::localescape)
+        KeepInEntry = true;
+    }
+    if (KeepInEntry)
+      IP = moveBeforeInsertPoint(I, IP);
+  }
+  return IP;
+}
+
 /// initializeInstrumentation - Initialize all passes in the TransformUtils
 /// library.
 void llvm::initializeInstrumentation(PassRegistry &Registry) {