lib/CodeGen/TargetOptionsImpl.cpp

   1 //===-- TargetOptionsImpl.cpp - Options that apply to all targets ----------==//
   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 file implements the methods in the TargetOptions.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/CodeGen/MachineFrameInfo.h"
  14 #include "llvm/CodeGen/MachineFunction.h"
  15 #include "llvm/CodeGen/TargetFrameLowering.h"
  16 #include "llvm/CodeGen/TargetSubtargetInfo.h"
  17 #include "llvm/IR/Function.h"
  18 #include "llvm/IR/Module.h"
  19 #include "llvm/Target/TargetOptions.h"
  20 using namespace llvm;
  21
  22 /// DisableFramePointerElim - This returns true if frame pointer elimination
  23 /// optimization should be disabled for the given machine function.
  24 bool TargetOptions::DisableFramePointerElim(const MachineFunction &MF) const {
  25   // Check to see if the target want to forcably keep frame pointer.
  26   if (MF.getSubtarget().getFrameLowering()->keepFramePointer(MF))
  27     return true;
  28
  29   const Function &F = MF.getFunction();
  30
  31   // TODO: Remove support for old `fp elim` function attributes after fully
  32   //       migrate to use "frame-pointer"
  33   if (!F.hasFnAttribute("frame-pointer")) {
  34     // Check to see if we should eliminate all frame pointers.
  35     if (F.getFnAttribute("no-frame-pointer-elim").getValueAsString() == "true")
  36       return true;
  37
  38     // Check to see if we should eliminate non-leaf frame pointers.
  39     if (F.hasFnAttribute("no-frame-pointer-elim-non-leaf"))
  40       return MF.getFrameInfo().hasCalls();
  41
  42     return false;
  43   }
  44
  45   StringRef FP = F.getFnAttribute("frame-pointer").getValueAsString();
  46   if (FP == "all")
  47     return true;
  48   if (FP == "non-leaf")
  49     return MF.getFrameInfo().hasCalls();
  50   if (FP == "none")
  51     return false;
  52   llvm_unreachable("unknown frame pointer flag");
  53 }
  54
  55 /// HonorSignDependentRoundingFPMath - Return true if the codegen must assume
  56 /// that the rounding mode of the FPU can change from its default.
  57 bool TargetOptions::HonorSignDependentRoundingFPMath() const {
  58   return !UnsafeFPMath && HonorSignDependentRoundingFPMathOption;
  59 }