[PATCH] D72754: [BasicBlock] add helper getPostdominatingDeoptimizeCall

[Fedor Sergeev via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG8a4d12ae5b3e: [BasicBlock] add helper getPostdominatingDeoptimizeCall (authored by fedor.sergeev).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D72754/new/

https://reviews.llvm.org/D72754

Files:
  llvm/include/llvm/IR/BasicBlock.h
  llvm/lib/IR/BasicBlock.cpp
  llvm/lib/Transforms/Scalar/LoopPredication.cpp


Index: llvm/lib/Transforms/Scalar/LoopPredication.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopPredication.cpp
+++ llvm/lib/Transforms/Scalar/LoopPredication.cpp
@@ -1020,17 +1020,6 @@
   return SE.getUMinFromMismatchedTypes(ExitCounts);
 }
 
-/// Return true if we can be fairly sure that executing block BB will probably
-/// lead to executing an __llvm_deoptimize.  This is a profitability heuristic,
-/// not a legality constraint.
-static bool isVeryLikelyToDeopt(BasicBlock *BB) {
-  while (BB->getUniqueSuccessor())
-    // Will skip side effects, that's okay
-    BB = BB->getUniqueSuccessor();
-
-  return BB->getTerminatingDeoptimizeCall();
-}
-
 /// This implements an analogous, but entirely distinct transform from the main
 /// loop predication transform.  This one is phrased in terms of using a
 /// widenable branch *outside* the loop to allow us to simplify loop exits in a
@@ -1150,10 +1139,13 @@
 
     const bool ExitIfTrue = !L->contains(*succ_begin(ExitingBB));
     BasicBlock *ExitBB = BI->getSuccessor(ExitIfTrue ? 0 : 1);
-    if (!isVeryLikelyToDeopt(ExitBB))
-      // Profitability: indicator of rarely/never taken exit
+    if (!ExitBB->getPostdominatingDeoptimizeCall())
       continue;
 
+    /// Here we can be fairly sure that executing this exit will most likely
+    /// lead to executing llvm.experimental.deoptimize.
+    /// This is a profitability heuristic, not a legality constraint.
+
     // If we found a widenable exit condition, do two things:
     // 1) fold the widened exit test into the widenable condition
     // 2) fold the branch to untaken - avoids infinite looping
Index: llvm/lib/IR/BasicBlock.cpp
===================================================================
--- llvm/lib/IR/BasicBlock.cpp
+++ llvm/lib/IR/BasicBlock.cpp
@@ -193,6 +193,13 @@
   return nullptr;
 }
 
+const CallInst *BasicBlock::getPostdominatingDeoptimizeCall() const {
+  const BasicBlock* BB = this;
+  while (BB->getUniqueSuccessor())
+    BB = BB->getUniqueSuccessor();
+  return BB->getTerminatingDeoptimizeCall();
+}
+
 const Instruction* BasicBlock::getFirstNonPHI() const {
   for (const Instruction &I : *this)
     if (!isa<PHINode>(I))
Index: llvm/include/llvm/IR/BasicBlock.h
===================================================================
--- llvm/include/llvm/IR/BasicBlock.h
+++ llvm/include/llvm/IR/BasicBlock.h
@@ -133,6 +133,15 @@
          static_cast<const BasicBlock *>(this)->getTerminatingDeoptimizeCall());
   }
 
+  /// Returns the call instruction calling \@llvm.experimental.deoptimize
+  /// that is present either in current basic block or in block that is a unique
+  /// successor to current block, if such call is present. Otherwise, returns null.
+  const CallInst *getPostdominatingDeoptimizeCall() const;
+  CallInst *getPostdominatingDeoptimizeCall() {
+    return const_cast<CallInst *>(
+         static_cast<const BasicBlock *>(this)->getPostdominatingDeoptimizeCall());
+  }
+
   /// Returns the call instruction marked 'musttail' prior to the terminating
   /// return instruction of this basic block, if such a call is present.
   /// Otherwise, returns null.


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