[CSSPGO] IR intrinsic for pseudo-probe block instrumentation

This change introduces a new IR intrinsic named `llvm.pseudoprobe` for pseudo-probe block instrumentation. Please refer to https://reviews.llvm.org/D86193 for the whole story.

A pseudo probe is used to collect the execution count of the block where the probe is instrumented. This requires a pseudo probe to be persisting. The LLVM PGO instrumentation also instruments in similar places by placing a counter in the form of atomic read/write operations or runtime helper calls. While these operations are very persisting or optimization-resilient, in theory we can borrow the atomic read/write implementation from PGO counters and cut it off at the end of compilation with all the atomics converted into binary data. This was our initial design and we’ve seen promising sample correlation quality with it. However, the atomics approach has a couple issues:

1. IR Optimizations are blocked unexpectedly. Those atomic instructions are not going to be physically present in the binary code, but since they are on the IR till very end of compilation, they can still prevent certain IR optimizations and result in lower code quality.
2. The counter atomics may not be fully cleaned up from the code stream eventually.
3. Extra work is needed for re-targeting.

We choose to implement pseudo probes based on a special LLVM intrinsic, which is expected to have most of the semantics that comes with an atomic operation but does not block desired optimizations as much as possible. More specifically the semantics associated with the new intrinsic enforces a pseudo probe to be virtually executed exactly the same number of times before and after an IR optimization. The intrinsic also comes with certain flags that are carefully chosen so that the places they are probing are not going to be messed up by the optimizer while most of the IR optimizations still work. The core flags given to the special intrinsic is `IntrInaccessibleMemOnly`, which means the intrinsic accesses memory and does have a side effect so that it is not removable, but is does not access memory locations that are accessible by any original instructions. This way the intrinsic does not alias with any original instruction and thus it does not block optimizations as much as an atomic operation does. We also assign a function GUID and a block index to an intrinsic so that they are uniquely identified and not merged in order to achieve good correlation quality.

Let's now look at an example. Given the following LLVM IR:

```
define internal void @foo2(i32 %x, void (i32)* %f) !dbg !4 {
bb0:
  %cmp = icmp eq i32 %x, 0
   br i1 %cmp, label %bb1, label %bb2
bb1:
   br label %bb3
bb2:
   br label %bb3
bb3:
   ret void
}
```

The instrumented IR will look like below. Note that each `llvm.pseudoprobe` intrinsic call represents a pseudo probe at a block, of which the first parameter is the GUID of the probe’s owner function and the second parameter is the probe’s ID.

```
define internal void @foo2(i32 %x, void (i32)* %f) !dbg !4 {
bb0:
   %cmp = icmp eq i32 %x, 0
   call void @llvm.pseudoprobe(i64 837061429793323041, i64 1)
   br i1 %cmp, label %bb1, label %bb2
bb1:
   call void @llvm.pseudoprobe(i64 837061429793323041, i64 2)
   br label %bb3
bb2:
   call void @llvm.pseudoprobe(i64 837061429793323041, i64 3)
   br label %bb3
bb3:
   call void @llvm.pseudoprobe(i64 837061429793323041, i64 4)
   ret void
}

```

Reviewed By: wmi

Differential Revision: https://reviews.llvm.org/D86490

diff --git a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
index ed99740..b484784 100644 (file)
--- a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -526,6 +526,7 @@ public:
     case Intrinsic::annotation:
     case Intrinsic::assume:
     case Intrinsic::sideeffect:
+    case Intrinsic::pseudoprobe:
     case Intrinsic::dbg_declare:
     case Intrinsic::dbg_value:
     case Intrinsic::dbg_label:

diff --git a/llvm/include/llvm/CodeGen/BasicTTIImpl.h b/llvm/include/llvm/CodeGen/BasicTTIImpl.h
index e6f837e..91c426f 100644 (file)
--- a/llvm/include/llvm/CodeGen/BasicTTIImpl.h
+++ b/llvm/include/llvm/CodeGen/BasicTTIImpl.h
@@ -1436,6 +1436,7 @@ public:
     case Intrinsic::lifetime_start:
     case Intrinsic::lifetime_end:
     case Intrinsic::sideeffect:
+    case Intrinsic::pseudoprobe:
       return 0;
     case Intrinsic::masked_store: {
       Type *Ty = Tys[0];

diff --git a/llvm/include/llvm/IR/BasicBlock.h b/llvm/include/llvm/IR/BasicBlock.h
index 24d568a..26cfdd9 100644 (file)
--- a/llvm/include/llvm/IR/BasicBlock.h
+++ b/llvm/include/llvm/IR/BasicBlock.h
@@ -165,19 +165,24 @@ public:
   }
 
   /// Returns a pointer to the first instruction in this block that is not a
-  /// PHINode or a debug intrinsic.
-  const Instruction* getFirstNonPHIOrDbg() const;
-  Instruction* getFirstNonPHIOrDbg() {
+  /// PHINode or a debug intrinsic, or any pseudo operation if \c SkipPseudoOp
+  /// is true.
+  const Instruction *getFirstNonPHIOrDbg(bool SkipPseudoOp = false) const;
+  Instruction *getFirstNonPHIOrDbg(bool SkipPseudoOp = false) {
     return const_cast<Instruction *>(
-                  static_cast<const BasicBlock *>(this)->getFirstNonPHIOrDbg());
+        static_cast<const BasicBlock *>(this)->getFirstNonPHIOrDbg(
+            SkipPseudoOp));
   }
 
   /// Returns a pointer to the first instruction in this block that is not a
-  /// PHINode, a debug intrinsic, or a lifetime intrinsic.
-  const Instruction* getFirstNonPHIOrDbgOrLifetime() const;
-  Instruction* getFirstNonPHIOrDbgOrLifetime() {
+  /// PHINode, a debug intrinsic, or a lifetime intrinsic, or any pseudo
+  /// operation if \c SkipPseudoOp is true.
+  const Instruction *
+  getFirstNonPHIOrDbgOrLifetime(bool SkipPseudoOp = false) const;
+  Instruction *getFirstNonPHIOrDbgOrLifetime(bool SkipPseudoOp = false) {
     return const_cast<Instruction *>(
-        static_cast<const BasicBlock *>(this)->getFirstNonPHIOrDbgOrLifetime());
+        static_cast<const BasicBlock *>(this)->getFirstNonPHIOrDbgOrLifetime(
+            SkipPseudoOp));
   }
 
   /// Returns an iterator to the first instruction in this block that is
@@ -191,16 +196,18 @@ public:
   }
 
   /// Return a const iterator range over the instructions in the block, skipping
-  /// any debug instructions.
+  /// any debug instructions. Skip any pseudo operations as well if \c
+  /// SkipPseudoOp is true.
   iterator_range<filter_iterator<BasicBlock::const_iterator,
                                  std::function<bool(const Instruction &)>>>
-  instructionsWithoutDebug() const;
+  instructionsWithoutDebug(bool SkipPseudoOp = false) const;
 
   /// Return an iterator range over the instructions in the block, skipping any
-  /// debug instructions.
-  iterator_range<filter_iterator<BasicBlock::iterator,
-                                 std::function<bool(Instruction &)>>>
-  instructionsWithoutDebug();
+  /// debug instructions. Skip and any pseudo operations as well if \c
+  /// SkipPseudoOp is true.
+  iterator_range<
+      filter_iterator<BasicBlock::iterator, std::function<bool(Instruction &)>>>
+  instructionsWithoutDebug(bool SkipPseudoOp = false);
 
   /// Return the size of the basic block ignoring debug instructions
   filter_iterator<BasicBlock::const_iterator,

diff --git a/llvm/include/llvm/IR/Instruction.h b/llvm/include/llvm/IR/Instruction.h
index ef83a25..d2a55f8 100644 (file)
--- a/llvm/include/llvm/IR/Instruction.h
+++ b/llvm/include/llvm/IR/Instruction.h
@@ -651,19 +651,25 @@ public:
   bool isLifetimeStartOrEnd() const;
 
   /// Return a pointer to the next non-debug instruction in the same basic
-  /// block as 'this', or nullptr if no such instruction exists.
-  const Instruction *getNextNonDebugInstruction() const;
-  Instruction *getNextNonDebugInstruction() {
+  /// block as 'this', or nullptr if no such instruction exists. Skip any pseudo
+  /// operations if \c SkipPseudoOp is true.
+  const Instruction *
+  getNextNonDebugInstruction(bool SkipPseudoOp = false) const;
+  Instruction *getNextNonDebugInstruction(bool SkipPseudoOp = false) {
     return const_cast<Instruction *>(
-        static_cast<const Instruction *>(this)->getNextNonDebugInstruction());
+        static_cast<const Instruction *>(this)->getNextNonDebugInstruction(
+            SkipPseudoOp));
   }
 
   /// Return a pointer to the previous non-debug instruction in the same basic
-  /// block as 'this', or nullptr if no such instruction exists.
-  const Instruction *getPrevNonDebugInstruction() const;
-  Instruction *getPrevNonDebugInstruction() {
+  /// block as 'this', or nullptr if no such instruction exists. Skip any pseudo
+  /// operations if \c SkipPseudoOp is true.
+  const Instruction *
+  getPrevNonDebugInstruction(bool SkipPseudoOp = false) const;
+  Instruction *getPrevNonDebugInstruction(bool SkipPseudoOp = false) {
     return const_cast<Instruction *>(
-        static_cast<const Instruction *>(this)->getPrevNonDebugInstruction());
+        static_cast<const Instruction *>(this)->getPrevNonDebugInstruction(
+            SkipPseudoOp));
   }
 
   /// Create a copy of 'this' instruction that is identical in all ways except

diff --git a/llvm/include/llvm/IR/IntrinsicInst.h b/llvm/include/llvm/IR/IntrinsicInst.h
index 9ba9ea6..5250458 100644 (file)
--- a/llvm/include/llvm/IR/IntrinsicInst.h
+++ b/llvm/include/llvm/IR/IntrinsicInst.h
@@ -967,6 +967,28 @@ public:
   }
 };
 
+class PseudoProbeInst : public IntrinsicInst {
+public:
+  static bool classof(const IntrinsicInst *I) {
+    return I->getIntrinsicID() == Intrinsic::pseudoprobe;
+  }
+
+  static bool classof(const Value *V) {
+    return isa<IntrinsicInst>(V) && classof(cast<IntrinsicInst>(V));
+  }
+
+  ConstantInt *getFuncGuid() const {
+    return cast<ConstantInt>(const_cast<Value *>(getArgOperand(0)));
+  }
+
+  ConstantInt *getAttributes() const {
+    return cast<ConstantInt>(const_cast<Value *>(getArgOperand(2)));
+  }
+
+  ConstantInt *getIndex() const {
+    return cast<ConstantInt>(const_cast<Value *>(getArgOperand(1)));
+  }
+};
 } // end namespace llvm
 
 #endif // LLVM_IR_INTRINSICINST_H

diff --git a/llvm/include/llvm/IR/Intrinsics.td b/llvm/include/llvm/IR/Intrinsics.td
index 0ea46c5..6f73178 100644 (file)
--- a/llvm/include/llvm/IR/Intrinsics.td
+++ b/llvm/include/llvm/IR/Intrinsics.td
@@ -1277,6 +1277,13 @@ def int_donothing : DefaultAttrsIntrinsic<[], [], [IntrNoMem, IntrWillReturn]>;
 // which specify that infinite loops must be preserved.
 def int_sideeffect : DefaultAttrsIntrinsic<[], [], [IntrInaccessibleMemOnly, IntrWillReturn]>;
 
+// The pseudoprobe intrinsic works as a place holder to the block it probes.
+// Like the sideeffect intrinsic defined above, this intrinsic is treated by the 
+// optimizer as having opaque side effects so that it won't be get rid of or moved 
+// out of the block it probes.
+def int_pseudoprobe : Intrinsic<[], [llvm_i64_ty, llvm_i64_ty, llvm_i32_ty],
+                                    [IntrInaccessibleMemOnly, IntrWillReturn]>;
+
 // Intrinsics to support half precision floating point format
 let IntrProperties = [IntrNoMem, IntrWillReturn] in {
 def int_convert_to_fp16   : DefaultAttrsIntrinsic<[llvm_i16_ty], [llvm_anyfloat_ty]>;

diff --git a/llvm/lib/Analysis/AliasSetTracker.cpp b/llvm/lib/Analysis/AliasSetTracker.cpp
index 6f8f192..44f7d95 100644 (file)
--- a/llvm/lib/Analysis/AliasSetTracker.cpp
+++ b/llvm/lib/Analysis/AliasSetTracker.cpp
@@ -439,6 +439,7 @@ void AliasSetTracker::addUnknown(Instruction *Inst) {
       // FIXME: Add lifetime/invariant intrinsics (See: PR30807).
     case Intrinsic::assume:
     case Intrinsic::sideeffect:
+    case Intrinsic::pseudoprobe:
       return;
     }
   }

diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index 0a2de5d..8a4b779 100644 (file)
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -1911,6 +1911,10 @@ CallAnalyzer::analyzeBlock(BasicBlock *BB,
     if (isa<DbgInfoIntrinsic>(I))
       continue;
 
+    // Skip pseudo-probes.
+    if (isa<PseudoProbeInst>(I))
+      continue;
+
     // Skip ephemeral values.
     if (EphValues.count(&*I))
       continue;

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index cdd07a6..9d57616 100644 (file)
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -527,6 +527,7 @@ bool llvm::isAssumeLikeIntrinsic(const Instruction *I) {
       // FIXME: This list is repeated from NoTTI::getIntrinsicCost.
       case Intrinsic::assume:
       case Intrinsic::sideeffect:
+      case Intrinsic::pseudoprobe:
       case Intrinsic::dbg_declare:
       case Intrinsic::dbg_value:
       case Intrinsic::dbg_label:

diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp
index e865087..bd69055 100644 (file)
--- a/llvm/lib/Analysis/VectorUtils.cpp
+++ b/llvm/lib/Analysis/VectorUtils.cpp
@@ -125,7 +125,7 @@ Intrinsic::ID llvm::getVectorIntrinsicIDForCall(const CallInst *CI,
 
   if (isTriviallyVectorizable(ID) || ID == Intrinsic::lifetime_start ||
       ID == Intrinsic::lifetime_end || ID == Intrinsic::assume ||
-      ID == Intrinsic::sideeffect)
+      ID == Intrinsic::sideeffect || ID == Intrinsic::pseudoprobe)
     return ID;
   return Intrinsic::not_intrinsic;
 }

diff --git a/llvm/lib/CodeGen/Analysis.cpp b/llvm/lib/CodeGen/Analysis.cpp
index 7da28ff..45099cd 100644 (file)
--- a/llvm/lib/CodeGen/Analysis.cpp
+++ b/llvm/lib/CodeGen/Analysis.cpp
@@ -537,6 +537,9 @@ bool llvm::isInTailCallPosition(const CallBase &Call, const TargetMachine &TM) {
     // Debug info intrinsics do not get in the way of tail call optimization.
     if (isa<DbgInfoIntrinsic>(BBI))
       continue;
+    // Pseudo probe intrinsics do not block tail call optimization either.
+    if (isa<PseudoProbeInst>(BBI))
+      continue;
     // A lifetime end or assume intrinsic should not stop tail call
     // optimization.
     if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(BBI))

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index 06ed37c..825d3ee 100644 (file)
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -2241,13 +2241,12 @@ bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT
     // Skip over debug and the bitcast.
     do {
       ++BI;
-    } while (isa<DbgInfoIntrinsic>(BI) || &*BI == BCI || &*BI == EVI);
+    } while (isa<DbgInfoIntrinsic>(BI) || &*BI == BCI || &*BI == EVI ||
+             isa<PseudoProbeInst>(BI));
     if (&*BI != RetI)
       return false;
   } else {
-    BasicBlock::iterator BI = BB->begin();
-    while (isa<DbgInfoIntrinsic>(BI)) ++BI;
-    if (&*BI != RetI)
+    if (BB->getFirstNonPHIOrDbg(true) != RetI)
       return false;
   }
 
@@ -2272,18 +2271,12 @@ bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT
     for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
       if (!VisitedBBs.insert(*PI).second)
         continue;
-
-      BasicBlock::InstListType &InstList = (*PI)->getInstList();
-      BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
-      BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
-      do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
-      if (RI == RE)
-        continue;
-
-      CallInst *CI = dyn_cast<CallInst>(&*RI);
-      if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&
-          attributesPermitTailCall(F, CI, RetI, *TLI))
-        TailCallBBs.push_back(*PI);
+      if (Instruction *I = (*PI)->rbegin()->getPrevNonDebugInstruction(true)) {
+        CallInst *CI = dyn_cast<CallInst>(I);
+        if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&
+            attributesPermitTailCall(F, CI, RetI, *TLI))
+          TailCallBBs.push_back(*PI);
+      }
     }
   }
 

diff --git a/llvm/lib/IR/BasicBlock.cpp b/llvm/lib/IR/BasicBlock.cpp
index b1d7960..23a1184 100644 (file)
--- a/llvm/lib/IR/BasicBlock.cpp
+++ b/llvm/lib/IR/BasicBlock.cpp
@@ -97,18 +97,20 @@ void BasicBlock::setParent(Function *parent) {
 
 iterator_range<filter_iterator<BasicBlock::const_iterator,
                                std::function<bool(const Instruction &)>>>
-BasicBlock::instructionsWithoutDebug() const {
-  std::function<bool(const Instruction &)> Fn = [](const Instruction &I) {
-    return !isa<DbgInfoIntrinsic>(I);
+BasicBlock::instructionsWithoutDebug(bool SkipPseudoOp) const {
+  std::function<bool(const Instruction &)> Fn = [=](const Instruction &I) {
+    return !isa<DbgInfoIntrinsic>(I) &&
+           !(SkipPseudoOp && isa<PseudoProbeInst>(I));
   };
   return make_filter_range(*this, Fn);
 }
 
-iterator_range<filter_iterator<BasicBlock::iterator,
-                               std::function<bool(Instruction &)>>>
-BasicBlock::instructionsWithoutDebug() {
-  std::function<bool(Instruction &)> Fn = [](Instruction &I) {
-    return !isa<DbgInfoIntrinsic>(I);
+iterator_range<
+    filter_iterator<BasicBlock::iterator, std::function<bool(Instruction &)>>>
+BasicBlock::instructionsWithoutDebug(bool SkipPseudoOp) {
+  std::function<bool(Instruction &)> Fn = [=](Instruction &I) {
+    return !isa<DbgInfoIntrinsic>(I) &&
+           !(SkipPseudoOp && isa<PseudoProbeInst>(I));
   };
   return make_filter_range(*this, Fn);
 }
@@ -218,14 +220,21 @@ const Instruction* BasicBlock::getFirstNonPHI() const {
   return nullptr;
 }
 
-const Instruction* BasicBlock::getFirstNonPHIOrDbg() const {
-  for (const Instruction &I : *this)
-    if (!isa<PHINode>(I) && !isa<DbgInfoIntrinsic>(I))
-      return &I;
+const Instruction *BasicBlock::getFirstNonPHIOrDbg(bool SkipPseudoOp) const {
+  for (const Instruction &I : *this) {
+    if (isa<PHINode>(I) || isa<DbgInfoIntrinsic>(I))
+      continue;
+
+    if (SkipPseudoOp && isa<PseudoProbeInst>(I))
+      continue;
+
+    return &I;
+  }
   return nullptr;
 }
 
-const Instruction* BasicBlock::getFirstNonPHIOrDbgOrLifetime() const {
+const Instruction *
+BasicBlock::getFirstNonPHIOrDbgOrLifetime(bool SkipPseudoOp) const {
   for (const Instruction &I : *this) {
     if (isa<PHINode>(I) || isa<DbgInfoIntrinsic>(I))
       continue;
@@ -233,6 +242,9 @@ const Instruction* BasicBlock::getFirstNonPHIOrDbgOrLifetime() const {
     if (I.isLifetimeStartOrEnd())
       continue;
 
+    if (SkipPseudoOp && isa<PseudoProbeInst>(I))
+      continue;
+
     return &I;
   }
   return nullptr;

diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
index 04bd045..1e3fcd6 100644 (file)
--- a/llvm/lib/IR/Instruction.cpp
+++ b/llvm/lib/IR/Instruction.cpp
@@ -641,16 +641,18 @@ bool Instruction::isLifetimeStartOrEnd() const {
   return ID == Intrinsic::lifetime_start || ID == Intrinsic::lifetime_end;
 }
 
-const Instruction *Instruction::getNextNonDebugInstruction() const {
+const Instruction *
+Instruction::getNextNonDebugInstruction(bool SkipPseudoOp) const {
   for (const Instruction *I = getNextNode(); I; I = I->getNextNode())
-    if (!isa<DbgInfoIntrinsic>(I))
+    if (!isa<DbgInfoIntrinsic>(I) && !(SkipPseudoOp && isa<PseudoProbeInst>(I)))
       return I;
   return nullptr;
 }
 
-const Instruction *Instruction::getPrevNonDebugInstruction() const {
+const Instruction *
+Instruction::getPrevNonDebugInstruction(bool SkipPseudoOp) const {
   for (const Instruction *I = getPrevNode(); I; I = I->getPrevNode())
-    if (!isa<DbgInfoIntrinsic>(I))
+    if (!isa<DbgInfoIntrinsic>(I) && !(SkipPseudoOp && isa<PseudoProbeInst>(I)))
       return I;
   return nullptr;
 }

diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index 0c3ee85..b287a80 100644 (file)
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -543,6 +543,10 @@ static unsigned getJumpThreadDuplicationCost(BasicBlock *BB,
     // Debugger intrinsics don't incur code size.
     if (isa<DbgInfoIntrinsic>(I)) continue;
 
+    // Pseudo-probes don't incur code size.
+    if (isa<PseudoProbeInst>(I))
+      continue;
+
     // If this is a pointer->pointer bitcast, it is free.
     if (isa<BitCastInst>(I) && I->getType()->isPointerTy())
       continue;

diff --git a/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp b/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
index c5dc443..9e7cccc 100644 (file)
--- a/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
@@ -240,7 +240,11 @@ static bool markTails(Function &F, bool &AllCallsAreTailCalls,
         Escaped = ESCAPED;
 
       CallInst *CI = dyn_cast<CallInst>(&I);
-      if (!CI || CI->isTailCall() || isa<DbgInfoIntrinsic>(&I))
+      // A PseudoProbeInst has the IntrInaccessibleMemOnly tag hence it is
+      // considered accessing memory and will be marked as a tail call if we
+      // don't bail out here.
+      if (!CI || CI->isTailCall() || isa<DbgInfoIntrinsic>(&I) ||
+          isa<PseudoProbeInst>(&I))
         continue;
 
       bool IsNoTail = CI->isNoTailCall() || CI->hasOperandBundles();
@@ -752,7 +756,7 @@ bool TailRecursionEliminator::processBlock(
       return false;
 
     BasicBlock *Succ = BI->getSuccessor(0);
-    ReturnInst *Ret = dyn_cast<ReturnInst>(Succ->getFirstNonPHIOrDbg());
+    ReturnInst *Ret = dyn_cast<ReturnInst>(Succ->getFirstNonPHIOrDbg(true));
 
     if (!Ret)
       return false;

diff --git a/llvm/lib/Transforms/Utils/Evaluator.cpp b/llvm/lib/Transforms/Utils/Evaluator.cpp
index c5dfbf9..6fe2938 100644 (file)
--- a/llvm/lib/Transforms/Utils/Evaluator.cpp
+++ b/llvm/lib/Transforms/Utils/Evaluator.cpp
@@ -551,6 +551,10 @@ bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst,
           LLVM_DEBUG(dbgs() << "Skipping sideeffect intrinsic.\n");
           ++CurInst;
           continue;
+        } else if (II->getIntrinsicID() == Intrinsic::pseudoprobe) {
+          LLVM_DEBUG(dbgs() << "Skipping pseudoprobe intrinsic.\n");
+          ++CurInst;
+          continue;
         }
 
         LLVM_DEBUG(dbgs() << "Unknown intrinsic. Can not evaluate.\n");

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index a48a335..7aeeee4 100644 (file)
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1981,7 +1981,9 @@ static Value *isSafeToSpeculateStore(Instruction *I, BasicBlock *BrBB,
 
   // Look for a store to the same pointer in BrBB.
   unsigned MaxNumInstToLookAt = 9;
-  for (Instruction &CurI : reverse(BrBB->instructionsWithoutDebug())) {
+  // Skip pseudo probe intrinsic calls which are not really killing any memory
+  // accesses.
+  for (Instruction &CurI : reverse(BrBB->instructionsWithoutDebug(true))) {
     if (!MaxNumInstToLookAt)
       break;
     --MaxNumInstToLookAt;
@@ -2141,6 +2143,14 @@ bool SimplifyCFGOpt::SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *ThenBB,
       continue;
     }
 
+    // Skip pseudo probes. The consequence is we lose track of the branch
+    // probability for ThenBB, which is fine since the optimization here takes
+    // place regardless of the branch probability.
+    if (isa<PseudoProbeInst>(I)) {
+      SpeculatedDbgIntrinsics.push_back(I);
+      continue;
+    }
+
     // Only speculatively execute a single instruction (not counting the
     // terminator) for now.
     ++SpeculatedInstructions;
@@ -2495,7 +2505,8 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI,
   } else {
     DomBlock = *pred_begin(IfBlock1);
     for (BasicBlock::iterator I = IfBlock1->begin(); !I->isTerminator(); ++I)
-      if (!AggressiveInsts.count(&*I) && !isa<DbgInfoIntrinsic>(I)) {
+      if (!AggressiveInsts.count(&*I) && !isa<DbgInfoIntrinsic>(I) &&
+          !isa<PseudoProbeInst>(I)) {
         // This is not an aggressive instruction that we can promote.
         // Because of this, we won't be able to get rid of the control flow, so
         // the xform is not worth it.
@@ -2508,7 +2519,8 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI,
   } else {
     DomBlock = *pred_begin(IfBlock2);
     for (BasicBlock::iterator I = IfBlock2->begin(); !I->isTerminator(); ++I)
-      if (!AggressiveInsts.count(&*I) && !isa<DbgInfoIntrinsic>(I)) {
+      if (!AggressiveInsts.count(&*I) && !isa<DbgInfoIntrinsic>(I) &&
+          !isa<PseudoProbeInst>(I)) {
         // This is not an aggressive instruction that we can promote.
         // Because of this, we won't be able to get rid of the control flow, so
         // the xform is not worth it.

diff --git a/llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp b/llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
index 770e6e3..6ec5590 100644 (file)
--- a/llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
@@ -666,6 +666,10 @@ Vectorizer::getVectorizablePrefix(ArrayRef<Instruction *> Chain) {
                cast<IntrinsicInst>(&I)->getIntrinsicID() ==
                    Intrinsic::sideeffect) {
       // Ignore llvm.sideeffect calls.
+    } else if (isa<IntrinsicInst>(&I) &&
+               cast<IntrinsicInst>(&I)->getIntrinsicID() ==
+                   Intrinsic::pseudoprobe) {
+      // Ignore llvm.pseudoprobe calls.
     } else if (IsLoadChain && (I.mayWriteToMemory() || I.mayThrow())) {
       LLVM_DEBUG(dbgs() << "LSV: Found may-write/throw operation: " << I
                         << '\n');

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 7404c92..a6cdcd7 100644 (file)
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7407,7 +7407,8 @@ VPWidenCallRecipe *VPRecipeBuilder::tryToWidenCall(CallInst *CI, VFRange &Range,
 
   Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
   if (ID && (ID == Intrinsic::assume || ID == Intrinsic::lifetime_end ||
-             ID == Intrinsic::lifetime_start || ID == Intrinsic::sideeffect))
+             ID == Intrinsic::lifetime_start || ID == Intrinsic::sideeffect ||
+             ID == Intrinsic::pseudoprobe))
     return nullptr;
 
   auto willWiden = [&](ElementCount VF) -> bool {

diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 2da3de2..ca71aea 100644 (file)
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -5261,7 +5261,9 @@ void BoUpSLP::BlockScheduling::initScheduleData(Instruction *FromI,
 
     if (I->mayReadOrWriteMemory() &&
         (!isa<IntrinsicInst>(I) ||
-         cast<IntrinsicInst>(I)->getIntrinsicID() != Intrinsic::sideeffect)) {
+         (cast<IntrinsicInst>(I)->getIntrinsicID() != Intrinsic::sideeffect &&
+          cast<IntrinsicInst>(I)->getIntrinsicID() !=
+              Intrinsic::pseudoprobe))) {
       // Update the linked list of memory accessing instructions.
       if (CurrentLoadStore) {
         CurrentLoadStore->NextLoadStore = SD;