From 2f27339050f369baef0fc9b85d7a74854d9ea02d Mon Sep 17 00:00:00 2001
From: Edd Barrett <vext01@gmail.com>
Date: Thu, 20 Jan 2022 14:28:14 +0000
Subject: [PATCH 1/2] Check that yk_control_point() is called inside an
 interpreter loop.

We check that `yk_control_point()` is called from inside what appears to
be an interpreter loop, i.e. from within an outermost loop in a
function.
---
 llvm/lib/Transforms/Yk/ControlPoint.cpp | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Transforms/Yk/ControlPoint.cpp b/llvm/lib/Transforms/Yk/ControlPoint.cpp
index 033bc495b81238..064c3d709c2b9e 100644
--- a/llvm/lib/Transforms/Yk/ControlPoint.cpp
+++ b/llvm/lib/Transforms/Yk/ControlPoint.cpp
@@ -45,6 +45,7 @@
 // is shown as C code for easy comprehension.
 
 #include "llvm/Transforms/Yk/ControlPoint.h"
+#include "llvm/Analysis/LoopInfo.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Instructions.h"
@@ -121,8 +122,18 @@ class YkControlPoint : public ModulePass {
     // Get function containing the control point.
     Function *Caller = OldCtrlPointCall->getFunction();
 
-    // Find all live variables just before the call to the control point.
+    // Check that the control point is inside a loop.
     DominatorTree DT(*Caller);
+    const LoopInfo Loops(DT);
+    if (!std::any_of(Loops.begin(), Loops.end(), [OldCtrlPointCall](Loop *L) {
+          return L->contains(OldCtrlPointCall);
+        })) {
+      ;
+      Context.emitError("yk_control_point() must be called inside a loop.");
+      return false;
+    }
+
+    // Find all live variables just before the call to the control point.
     std::vector<Value *> LiveVals = getLiveVars(DT, OldCtrlPointCall);
     if (LiveVals.size() == 0) {
       Context.emitError(

From 1bf5b5f6d501e886304a36ba5db1f69b711eda7b Mon Sep 17 00:00:00 2001
From: Edd Barrett <vext01@gmail.com>
Date: Thu, 20 Jan 2022 14:40:42 +0000
Subject: [PATCH 2/2] Unify/sort headers in ControlPoint.cpp.

---
 llvm/lib/Transforms/Yk/ControlPoint.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Transforms/Yk/ControlPoint.cpp b/llvm/lib/Transforms/Yk/ControlPoint.cpp
index 064c3d709c2b9e..a3c8b66f18a76a 100644
--- a/llvm/lib/Transforms/Yk/ControlPoint.cpp
+++ b/llvm/lib/Transforms/Yk/ControlPoint.cpp
@@ -47,14 +47,14 @@
 #include "llvm/Transforms/Yk/ControlPoint.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Dominators.h"
 #include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Module.h"
+#include "llvm/IR/Verifier.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
-#include <llvm/IR/Dominators.h>
-#include <llvm/IR/IRBuilder.h>
-#include <llvm/IR/Verifier.h>
 
 #define DEBUG_TYPE "yk-control-point"
 #define JIT_STATE_PREFIX "jit-state: "