1 files changed, 71 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/LazyBlockFrequencyInfo.cpp b/llvm/lib/Analysis/LazyBlockFrequencyInfo.cpp
new file mode 100644
index 000000000000..439758560284
--- /dev/null
+++ b/llvm/lib/Analysis/LazyBlockFrequencyInfo.cpp
@@ -0,0 +1,71 @@
+//===- LazyBlockFrequencyInfo.cpp - Lazy Block Frequency Analysis ---------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This is an alternative analysis pass to BlockFrequencyInfoWrapperPass.  The
+// difference is that with this pass the block frequencies are not computed when
+// the analysis pass is executed but rather when the BFI result is explicitly
+// requested by the analysis client.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/LazyBlockFrequencyInfo.h"
+#include "llvm/Analysis/LazyBranchProbabilityInfo.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/Dominators.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "lazy-block-freq"
+
+INITIALIZE_PASS_BEGIN(LazyBlockFrequencyInfoPass, DEBUG_TYPE,
+                      "Lazy Block Frequency Analysis", true, true)
+INITIALIZE_PASS_DEPENDENCY(LazyBPIPass)
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
+INITIALIZE_PASS_END(LazyBlockFrequencyInfoPass, DEBUG_TYPE,
+                    "Lazy Block Frequency Analysis", true, true)
+
+char LazyBlockFrequencyInfoPass::ID = 0;
+
+LazyBlockFrequencyInfoPass::LazyBlockFrequencyInfoPass() : FunctionPass(ID) {
+  initializeLazyBlockFrequencyInfoPassPass(*PassRegistry::getPassRegistry());
+}
+
+void LazyBlockFrequencyInfoPass::print(raw_ostream &OS, const Module *) const {
+  LBFI.getCalculated().print(OS);
+}
+
+void LazyBlockFrequencyInfoPass::getAnalysisUsage(AnalysisUsage &AU) const {
+  LazyBranchProbabilityInfoPass::getLazyBPIAnalysisUsage(AU);
+  // We require DT so it's available when LI is available. The LI updating code
+  // asserts that DT is also present so if we don't make sure that we have DT
+  // here, that assert will trigger.
+  AU.addRequired<DominatorTreeWrapperPass>();
+  AU.addRequired<LoopInfoWrapperPass>();
+  AU.setPreservesAll();
+}
+
+void LazyBlockFrequencyInfoPass::releaseMemory() { LBFI.releaseMemory(); }
+
+bool LazyBlockFrequencyInfoPass::runOnFunction(Function &F) {
+  auto &BPIPass = getAnalysis<LazyBranchProbabilityInfoPass>();
+  LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+  LBFI.setAnalysis(&F, &BPIPass, &LI);
+  return false;
+}
+
+void LazyBlockFrequencyInfoPass::getLazyBFIAnalysisUsage(AnalysisUsage &AU) {
+  LazyBranchProbabilityInfoPass::getLazyBPIAnalysisUsage(AU);
+  AU.addRequired<LazyBlockFrequencyInfoPass>();
+  AU.addRequired<LoopInfoWrapperPass>();
+}
+
+void llvm::initializeLazyBFIPassPass(PassRegistry &Registry) {
+  initializeLazyBPIPassPass(Registry);
+  INITIALIZE_PASS_DEPENDENCY(LazyBlockFrequencyInfoPass);
+  INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass);
+}