From c0981da47d5696fe36474fcf86b4ce03ae3ff818 Mon Sep 17 00:00:00 2001
From: Dimitry Andric <dim@FreeBSD.org>
Date: Fri, 19 Nov 2021 21:06:13 +0100
Subject: Vendor import of llvm-project main
 llvmorg-14-init-10186-gff7f2cfa959b.

---
 llvm/lib/Transforms/Utils/BasicBlockUtils.cpp | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

(limited to 'llvm/lib/Transforms/Utils/BasicBlockUtils.cpp')

diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index ee933b638a23..6469c899feea 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -39,6 +39,7 @@
 #include "llvm/IR/Value.h"
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Utils/Local.h"
@@ -52,6 +53,12 @@ using namespace llvm;
 
 #define DEBUG_TYPE "basicblock-utils"
 
+static cl::opt<unsigned> MaxDeoptOrUnreachableSuccessorCheckDepth(
+    "max-deopt-or-unreachable-succ-check-depth", cl::init(8), cl::Hidden,
+    cl::desc("Set the maximum path length when checking whether a basic block "
+             "is followed by a block that either has a terminating "
+             "deoptimizing call or is terminated with an unreachable"));
+
 void llvm::DetatchDeadBlocks(
     ArrayRef<BasicBlock *> BBs,
     SmallVectorImpl<DominatorTree::UpdateType> *Updates,
@@ -230,7 +237,7 @@ bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, DomTreeUpdater *DTU,
   if (DTU) {
     SmallPtrSet<BasicBlock *, 2> SuccsOfBB(succ_begin(BB), succ_end(BB));
     SmallPtrSet<BasicBlock *, 2> SuccsOfPredBB(succ_begin(PredBB),
-                                               succ_begin(PredBB));
+                                               succ_end(PredBB));
     Updates.reserve(Updates.size() + 2 * SuccsOfBB.size() + 1);
     // Add insert edges first. Experimentally, for the particular case of two
     // blocks that can be merged, with a single successor and single predecessor
@@ -485,6 +492,20 @@ void llvm::ReplaceInstWithInst(BasicBlock::InstListType &BIL,
   BI = New;
 }
 
+bool llvm::IsBlockFollowedByDeoptOrUnreachable(const BasicBlock *BB) {
+  // Remember visited blocks to avoid infinite loop
+  SmallPtrSet<const BasicBlock *, 8> VisitedBlocks;
+  unsigned Depth = 0;
+  while (BB && Depth++ < MaxDeoptOrUnreachableSuccessorCheckDepth &&
+         VisitedBlocks.insert(BB).second) {
+    if (BB->getTerminatingDeoptimizeCall() ||
+        isa<UnreachableInst>(BB->getTerminator()))
+      return true;
+    BB = BB->getUniqueSuccessor();
+  }
+  return false;
+}
+
 void llvm::ReplaceInstWithInst(Instruction *From, Instruction *To) {
   BasicBlock::iterator BI(From);
   ReplaceInstWithInst(From->getParent()->getInstList(), BI, To);
-- 
cgit v1.2.3