include/llvm/Transforms/Utils/MisExpect.h

   1 //===--- MisExpect.h - Check the use of llvm.expect with PGO data ---------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This contains code to emit warnings for potentially incorrect usage of the
  10 // llvm.expect intrinsic. This utility extracts the threshold values from
  11 // metadata associated with the instrumented Branch or Switch instruction. The
  12 // threshold values are then used to determine if a warning should be emmited.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "llvm/ADT/SmallVector.h"
  17 #include "llvm/IR/Function.h"
  18 #include "llvm/IR/Instructions.h"
  19 #include "llvm/IR/LLVMContext.h"
  20
  21 namespace llvm {
  22 namespace misexpect {
  23
  24 /// verifyMisExpect - compares PGO counters to the thresholds used for
  25 /// llvm.expect and warns if the PGO counters are outside of the expected
  26 /// range.
  27 /// \param I The Instruction being checked
  28 /// \param Weights A vector of profile weights for each target block
  29 /// \param Ctx The current LLVM context
  30 void verifyMisExpect(llvm::Instruction *I,
  31                      const llvm::SmallVector<uint32_t, 4> &Weights,
  32                      llvm::LLVMContext &Ctx);
  33
  34 /// checkClangInstrumentation - verify if llvm.expect matches PGO profile
  35 /// This function checks the frontend instrumentation in the backend when
  36 /// lowering llvm.expect intrinsics. It checks for existing metadata, and
  37 /// then validates the use of llvm.expect against the assigned branch weights.
  38 //
  39 /// \param I the Instruction being checked
  40 void checkFrontendInstrumentation(Instruction &I);
  41
  42 } // namespace misexpect
  43 } // namespace llvm