[llvm] [PGO] Add ProfileInjector and ProfileVerifier passes (PR #147388)

[Snehasish Kumar via llvm-commits]

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@@ -0,0 +1,116 @@
+//===- ProfileVerify.cpp - Verify profile info for testing ----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/ProfileVerify.h"
+#include "llvm/ADT/DynamicAPInt.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Analysis/BranchProbabilityInfo.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/Analysis.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/MDBuilder.h"
+#include "llvm/IR/ProfDataUtils.h"
+#include "llvm/Support/BranchProbability.h"
+
+using namespace llvm;
+namespace {
+class ProfileInjector {
+  Function &F;
+  FunctionAnalysisManager &FAM;
+
+public:
+  static const Instruction *
+  getTerminatorBenefitingFromMDProf(const BasicBlock &BB) {
+    if (succ_size(&BB) < 2)
+      return nullptr;
+    auto *Term = BB.getTerminator();
+    return (isa<BranchInst>(Term) || isa<SwitchInst>(Term) ||
+            isa<IndirectBrInst>(Term) || isa<SelectInst>(Term) ||
+            isa<CallBrInst>(Term))
+               ? Term
+               : nullptr;
+  }
+  static Instruction *getTerminatorBenefitingFromMDProf(BasicBlock &BB) {
+    return const_cast<Instruction *>(
+        getTerminatorBenefitingFromMDProf(const_cast<const BasicBlock &>(BB)));
+  }
+
+  ProfileInjector(Function &F, FunctionAnalysisManager &FAM) : F(F), FAM(FAM) {}
+  bool inject();
+};
+} // namespace
+
+bool ProfileInjector::inject() {
+  auto &BPI = FAM.getResult<BranchProbabilityAnalysis>(F);
+
+  bool Changed = false;
+  for (auto &BB : F) {
+    auto *Term = getTerminatorBenefitingFromMDProf(BB);
+    if (!Term)
+      continue;
+    if (Term->getMetadata(LLVMContext::MD_prof))
+      continue;
+    SmallVector<BranchProbability> Probs;
+    Probs.reserve(Term->getNumSuccessors());
+    for (auto I = 0U, E = Term->getNumSuccessors(); I < E; ++I)
+      Probs.emplace_back(BPI.getEdgeProbability(&BB, Term->getSuccessor(I)));
+
+    const auto *FirstZeroDenominator =
+        find_if(Probs, [](const BranchProbability &P) {
+          return P.getDenominator() == 0;
+        });
+    (void)FirstZeroDenominator;
+    assert(FirstZeroDenominator == Probs.end());
+    const auto *FirstNonzeroNumerator =
+        find_if(Probs, [](const BranchProbability &P) {
+          return P.getNumerator() != 0;
+        });
+    assert(FirstNonzeroNumerator != Probs.end());
+    DynamicAPInt LCM(Probs[0].getDenominator());
+    DynamicAPInt GCD(FirstNonzeroNumerator->getNumerator());
+    for (const auto &Prob : drop_begin(Probs)) {
+      if (!Prob.getNumerator())
+        continue;
+      LCM = llvm::lcm(LCM, DynamicAPInt(Prob.getDenominator()));
+      GCD = llvm::lcm(GCD, DynamicAPInt(Prob.getNumerator()));
+    }
+    SmallVector<uint32_t> Weights;
+    Weights.reserve(Term->getNumSuccessors());
+    for (const auto &Prob : Probs) {
+      auto W = Prob.getNumerator() * LCM / GCD;
+      Weights.emplace_back(static_cast<int32_t>((int64_t)W));
+    }
+    setBranchWeights(*Term, Weights, false);
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snehasish wrote:

Document the false param name?

https://github.com/llvm/llvm-project/pull/147388