TargetOptions.h

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//===-- llvm/Target/TargetOptions.h - Target Options ------------*- C++ -*-===//
//
// 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 file defines command line option flags that are shared across various
// targets.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_TARGET_TARGETOPTIONS_H
#define LLVM_TARGET_TARGETOPTIONS_H
 
#include "llvm/ADT/FloatingPointMode.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/Compiler.h"
 
#include <memory>
 
namespace llvm {
struct fltSemantics;
class MachineFunction;
class MemoryBuffer;
 
namespace FPOpFusion {
enum FPOpFusionMode {
  Fast,     // Enable fusion of FP ops wherever it's profitable.
  Standard, // Only allow fusion of 'blessed' ops (currently just fmuladd).
  Strict    // Never fuse FP-ops.
};
}
 
namespace JumpTable {
enum JumpTableType {
  Single,     // Use a single table for all indirect jumptable calls.
  Arity,      // Use one table per number of function parameters.
  Simplified, // Use one table per function type, with types projected
              // into 4 types: pointer to non-function, struct,
              // primitive, and function pointer.
  Full        // Use one table per unique function type
};
}
 
namespace ThreadModel {
enum Model {
  POSIX, // POSIX Threads
  Single // Single Threaded Environment
};
}
 
enum class BasicBlockSection {
  All,    // Use Basic Block Sections for all basic blocks.  A section
          // for every basic block can significantly bloat object file sizes.
  List,   // Get list of functions & BBs from a file. Selectively enables
          // basic block sections for a subset of basic blocks which can be
          // used to control object size bloats from creating sections.
  Preset, // Similar to list but the blocks are identified by passes which
          // seek to use Basic Block Sections, e.g. MachineFunctionSplitter.
          // This option cannot be set via the command line.
  None    // Do not use Basic Block Sections.
};
 
/// Identify a debugger for "tuning" the debug info.
///
/// The "debugger tuning" concept allows us to present a more intuitive
/// interface that unpacks into different sets of defaults for the various
/// individual feature-flag settings, that suit the preferences of the
/// various debuggers.  However, it's worth remembering that debuggers are
/// not the only consumers of debug info, and some variations in DWARF might
/// better be treated as target/platform issues. Fundamentally,
/// o if the feature is useful (or not) to a particular debugger, regardless
///   of the target, that's a tuning decision;
/// o if the feature is useful (or not) on a particular platform, regardless
///   of the debugger, that's a target decision.
/// It's not impossible to see both factors in some specific case.
enum class DebuggerKind {
  Default, ///< No specific tuning requested.
  GDB,     ///< Tune debug info for gdb.
  LLDB,    ///< Tune debug info for lldb.
  SCE,     ///< Tune debug info for SCE targets (e.g. PS4).
  DBX      ///< Tune debug info for dbx.
};
 
/// Enable abort calls when global instruction selection fails to lower/select
/// an instruction.
enum class GlobalISelAbortMode {
  Disable,        // Disable the abort.
  Enable,         // Enable the abort.
  DisableWithDiag // Disable the abort but emit a diagnostic on failure.
};
 
/// Indicates when and how the Swift async frame pointer bit should be set.
enum class SwiftAsyncFramePointerMode {
  /// Determine whether to set the bit statically or dynamically based
  /// on the deployment target.
  DeploymentBased,
  /// Always set the bit.
  Always,
  /// Never set the bit.
  Never,
};
 
/// \brief Enumeration value for AMDGPU code object version, which is the
/// code object version times 100.
enum CodeObjectVersionKind {
  COV_None,
  COV_2 = 200, // Unsupported.
  COV_3 = 300, // Unsupported.
  COV_4 = 400,
  COV_5 = 500,
  COV_6 = 600,
};
 
class TargetOptions {
public:
  TargetOptions()
      : NoInfsFPMath(false), NoNaNsFPMath(false), NoTrappingFPMath(true),
        NoSignedZerosFPMath(false), EnableAIXExtendedAltivecABI(false),
        HonorSignDependentRoundingFPMathOption(false), NoZerosInBSS(false),
        GuaranteedTailCallOpt(false), StackSymbolOrdering(true),
        EnableFastISel(false), EnableGlobalISel(false), UseInitArray(false),
        DisableIntegratedAS(false), FunctionSections(false),
        DataSections(false), IgnoreXCOFFVisibility(false),
        XCOFFTracebackTable(true), UniqueSectionNames(true),
        UniqueBasicBlockSectionNames(false), SeparateNamedSections(false),
        TrapUnreachable(false), NoTrapAfterNoreturn(false), TLSSize(0),
        EmulatedTLS(false), EnableTLSDESC(false), EnableIPRA(false),
        EmitStackSizeSection(false), EnableMachineOutliner(false),
        EnableMachineFunctionSplitter(false),
        EnableStaticDataPartitioning(false), SupportsDefaultOutlining(false),
        EmitAddrsig(false), BBAddrMap(false), EmitCallGraphSection(false),
        EmitCallSiteInfo(false), SupportsDebugEntryValues(false),
        EnableDebugEntryValues(false), ValueTrackingVariableLocations(false),
        ForceDwarfFrameSection(false), XRayFunctionIndex(true),
        DebugStrictDwarf(false), Hotpatch(false),
        PPCGenScalarMASSEntries(false), JMCInstrument(false),
        EnableCFIFixup(false), MisExpect(false), XCOFFReadOnlyPointers(false),
        VerifyArgABICompliance(true),
        FPDenormalMode(DenormalMode::IEEE, DenormalMode::IEEE) {}
 
  /// DisableFramePointerElim - This returns true if frame pointer elimination
  /// optimization should be disabled for the given machine function.
  LLVM_ABI bool DisableFramePointerElim(const MachineFunction &MF) const;
 
  /// FramePointerIsReserved - This returns true if the frame pointer must
  /// always either point to a new frame record or be un-modified in the given
  /// function.
  LLVM_ABI bool FramePointerIsReserved(const MachineFunction &MF) const;
 
  /// If greater than 0, override the default value of
  /// MCAsmInfo::BinutilsVersion.
  std::pair<int, int> BinutilsVersion{0, 0};
 
  /// NoInfsFPMath - This flag is enabled when the
  /// -enable-no-infs-fp-math flag is specified on the command line. When
  /// this flag is off (the default), the code generator is not allowed to
  /// assume the FP arithmetic arguments and results are never +-Infs.
  unsigned NoInfsFPMath : 1;
 
  /// NoNaNsFPMath - This flag is enabled when the
  /// -enable-no-nans-fp-math flag is specified on the command line. When
  /// this flag is off (the default), the code generator is not allowed to
  /// assume the FP arithmetic arguments and results are never NaNs.
  unsigned NoNaNsFPMath : 1;
 
  /// NoTrappingFPMath - This flag is enabled when the
  /// -enable-no-trapping-fp-math is specified on the command line. This
  /// specifies that there are no trap handlers to handle exceptions.
  unsigned NoTrappingFPMath : 1;
 
  /// NoSignedZerosFPMath - This flag is enabled when the
  /// -enable-no-signed-zeros-fp-math is specified on the command line. This
  /// specifies that optimizations are allowed to treat the sign of a zero
  /// argument or result as insignificant.
  unsigned NoSignedZerosFPMath : 1;
 
  /// EnableAIXExtendedAltivecABI - This flag returns true when -vec-extabi is
  /// specified. The code generator is then able to use both volatile and
  /// nonvolitle vector registers. When false, the code generator only uses
  /// volatile vector registers which is the default setting on AIX.
  unsigned EnableAIXExtendedAltivecABI : 1;
 
  /// HonorSignDependentRoundingFPMath - This returns true when the
  /// -enable-sign-dependent-rounding-fp-math is specified.  If this returns
  /// false (the default), the code generator is allowed to assume that the
  /// rounding behavior is the default (round-to-zero for all floating point
  /// to integer conversions, and round-to-nearest for all other arithmetic
  /// truncations).  If this is enabled (set to true), the code generator must
  /// assume that the rounding mode may dynamically change.
  unsigned HonorSignDependentRoundingFPMathOption : 1;
  LLVM_ABI bool HonorSignDependentRoundingFPMath() const;
 
  /// NoZerosInBSS - By default some codegens place zero-initialized data to
  /// .bss section. This flag disables such behaviour (necessary, e.g. for
  /// crt*.o compiling).
  unsigned NoZerosInBSS : 1;
 
  /// GuaranteedTailCallOpt - This flag is enabled when -tailcallopt is
  /// specified on the commandline. When the flag is on, participating targets
  /// will perform tail call optimization on all calls which use the fastcc
  /// calling convention and which satisfy certain target-independent
  /// criteria (being at the end of a function, having the same return type
  /// as their parent function, etc.), using an alternate ABI if necessary.
  unsigned GuaranteedTailCallOpt : 1;
 
  /// StackSymbolOrdering - When true, this will allow CodeGen to order
  /// the local stack symbols (for code size, code locality, or any other
  /// heuristics). When false, the local symbols are left in whatever order
  /// they were generated. Default is true.
  unsigned StackSymbolOrdering : 1;
 
  /// EnableFastISel - This flag enables fast-path instruction selection
  /// which trades away generated code quality in favor of reducing
  /// compile time.
  unsigned EnableFastISel : 1;
 
  /// EnableGlobalISel - This flag enables global instruction selection.
  unsigned EnableGlobalISel : 1;
 
  /// EnableGlobalISelAbort - Control abort behaviour when global instruction
  /// selection fails to lower/select an instruction.
  GlobalISelAbortMode GlobalISelAbort = GlobalISelAbortMode::Enable;
 
  /// Control when and how the Swift async frame pointer bit should
  /// be set.
  SwiftAsyncFramePointerMode SwiftAsyncFramePointer =
      SwiftAsyncFramePointerMode::Always;
 
  /// UseInitArray - Use .init_array instead of .ctors for static
  /// constructors.
  unsigned UseInitArray : 1;
 
  /// Disable the integrated assembler.
  unsigned DisableIntegratedAS : 1;
 
  /// Emit functions into separate sections.
  unsigned FunctionSections : 1;
 
  /// Emit data into separate sections.
  unsigned DataSections : 1;
 
  /// Do not emit visibility attribute for xcoff.
  unsigned IgnoreXCOFFVisibility : 1;
 
  /// Emit XCOFF traceback table.
  unsigned XCOFFTracebackTable : 1;
 
  unsigned UniqueSectionNames : 1;
 
  /// Use unique names for basic block sections.
  unsigned UniqueBasicBlockSectionNames : 1;
 
  /// Emit named sections with the same name into different sections.
  unsigned SeparateNamedSections : 1;
 
  /// Emit target-specific trap instruction for 'unreachable' IR instructions.
  unsigned TrapUnreachable : 1;
 
  /// Do not emit a trap instruction for 'unreachable' IR instructions behind
  /// noreturn calls, even if TrapUnreachable is true.
  unsigned NoTrapAfterNoreturn : 1;
 
  /// Bit size of immediate TLS offsets (0 == use the default).
  unsigned TLSSize : 8;
 
  /// EmulatedTLS - This flag enables emulated TLS model, using emutls
  /// function in the runtime library..
  unsigned EmulatedTLS : 1;
 
  /// EnableTLSDESC - This flag enables TLS Descriptors.
  unsigned EnableTLSDESC : 1;
 
  /// This flag enables InterProcedural Register Allocation (IPRA).
  unsigned EnableIPRA : 1;
 
  /// Emit section containing metadata on function stack sizes.
  unsigned EmitStackSizeSection : 1;
 
  /// Enables the MachineOutliner pass.
  unsigned EnableMachineOutliner : 1;
 
  /// Enables the MachineFunctionSplitter pass.
  unsigned EnableMachineFunctionSplitter : 1;
 
  /// Enables the StaticDataSplitter pass.
  unsigned EnableStaticDataPartitioning : 1;
 
  /// Set if the target supports default outlining behaviour.
  unsigned SupportsDefaultOutlining : 1;
 
  /// Emit address-significance table.
  unsigned EmitAddrsig : 1;
 
  // Emit the SHT_LLVM_BB_ADDR_MAP section containing basic block address
  // which can be used to map virtual addresses to machine basic blocks.
  unsigned BBAddrMap : 1;
 
  /// Emit basic blocks into separate sections.
  BasicBlockSection BBSections = BasicBlockSection::None;
 
  /// Memory Buffer that contains information on sampled basic blocks and used
  /// to selectively generate basic block sections.
  std::shared_ptr<MemoryBuffer> BBSectionsFuncListBuf;
 
  /// Emit section containing call graph metadata.
  unsigned EmitCallGraphSection : 1;
 
  /// The flag enables call site info production. It is used only for debug
  /// info, and it is restricted only to optimized code. This can be used for
  /// something else, so that should be controlled in the frontend.
  unsigned EmitCallSiteInfo : 1;
  /// Set if the target supports the debug entry values by default.
  unsigned SupportsDebugEntryValues : 1;
  /// When set to true, the EnableDebugEntryValues option forces production
  /// of debug entry values even if the target does not officially support
  /// it. Useful for testing purposes only. This flag should never be checked
  /// directly, always use \ref ShouldEmitDebugEntryValues instead.
  unsigned EnableDebugEntryValues : 1;
  /// NOTE: There are targets that still do not support the debug entry values
  /// production.
  LLVM_ABI bool ShouldEmitDebugEntryValues() const;
 
  // When set to true, use experimental new debug variable location tracking,
  // which seeks to follow the values of variables rather than their location,
  // post isel.
  unsigned ValueTrackingVariableLocations : 1;
 
  /// Emit DWARF debug frame section.
  unsigned ForceDwarfFrameSection : 1;
 
  /// Emit XRay Function Index section
  unsigned XRayFunctionIndex : 1;
 
  /// When set to true, don't use DWARF extensions in later DWARF versions.
  /// By default, it is set to false.
  unsigned DebugStrictDwarf : 1;
 
  /// Emit the hotpatch flag in CodeView debug.
  unsigned Hotpatch : 1;
 
  /// Enables scalar MASS conversions
  unsigned PPCGenScalarMASSEntries : 1;
 
  /// Enable JustMyCode instrumentation.
  unsigned JMCInstrument : 1;
 
  /// Enable the CFIFixup pass.
  unsigned EnableCFIFixup : 1;
 
  /// When set to true, enable MisExpect Diagnostics
  /// By default, it is set to false
  unsigned MisExpect : 1;
 
  /// When set to true, const objects with relocatable address values are put
  /// into the RO data section.
  unsigned XCOFFReadOnlyPointers : 1;
 
  /// When set to true, call/return argument extensions of narrow integers
  /// are verified in the target backend if it cares about them. This is
  /// not done with internal tools like llc that run many tests that ignore
  /// (lack) these extensions.
  unsigned VerifyArgABICompliance : 1;
 
  /// Name of the stack usage file (i.e., .su file) if user passes
  /// -fstack-usage. If empty, it can be implied that -fstack-usage is not
  /// passed on the command line.
  std::string StackUsageOutput;
 
  /// If greater than 0, override TargetLoweringBase::PrefLoopAlignment.
  unsigned LoopAlignment = 0;
 
  /// FloatABIType - This setting is set by -float-abi=xxx option is specfied
  /// on the command line. This setting may either be Default, Soft, or Hard.
  /// Default selects the target's default behavior. Soft selects the ABI for
  /// software floating point, but does not indicate that FP hardware may not
  /// be used. Such a combination is unfortunately popular (e.g.
  /// arm-apple-darwin). Hard presumes that the normal FP ABI is used.
  FloatABI::ABIType FloatABIType = FloatABI::Default;
 
  /// AllowFPOpFusion - This flag is set by the -fp-contract=xxx option.
  /// This controls the creation of fused FP ops that store intermediate
  /// results in higher precision than IEEE allows (E.g. FMAs).
  ///
  /// Fast mode - allows formation of fused FP ops whenever they're
  /// profitable.
  /// Standard mode - allow fusion only for 'blessed' FP ops. At present the
  /// only blessed op is the fmuladd intrinsic. In the future more blessed ops
  /// may be added.
  /// Strict mode - allow fusion only if/when it can be proven that the excess
  /// precision won't effect the result.
  ///
  /// Note: This option only controls formation of fused ops by the
  /// optimizers.  Fused operations that are explicitly specified (e.g. FMA
  /// via the llvm.fma.* intrinsic) will always be honored, regardless of
  /// the value of this option.
  FPOpFusion::FPOpFusionMode AllowFPOpFusion = FPOpFusion::Standard;
 
  /// ThreadModel - This flag specifies the type of threading model to assume
  /// for things like atomics
  ThreadModel::Model ThreadModel = ThreadModel::POSIX;
 
  /// EABIVersion - This flag specifies the EABI version
  EABI EABIVersion = EABI::Default;
 
  /// Which debugger to tune for.
  DebuggerKind DebuggerTuning = DebuggerKind::Default;
 
private:
  /// Flushing mode to assume in default FP environment.
  DenormalMode FPDenormalMode;
 
  /// Flushing mode to assume in default FP environment, for float/vector of
  /// float.
  DenormalMode FP32DenormalMode;
 
public:
  void setFPDenormalMode(DenormalMode Mode) { FPDenormalMode = Mode; }
 
  void setFP32DenormalMode(DenormalMode Mode) { FP32DenormalMode = Mode; }
 
  DenormalMode getRawFPDenormalMode() const { return FPDenormalMode; }
 
  DenormalMode getRawFP32DenormalMode() const { return FP32DenormalMode; }
 
  LLVM_ABI DenormalMode getDenormalMode(const fltSemantics &FPType) const;
 
  /// What exception model to use
  ExceptionHandling ExceptionModel = ExceptionHandling::None;
 
  /// Machine level options.
  MCTargetOptions MCOptions;
 
  /// Stores the filename/path of the final .o/.obj file, to be written in the
  /// debug information. This is used for emitting the CodeView S_OBJNAME
  /// record.
  std::string ObjectFilenameForDebug;
};
 
} // namespace llvm
 
#endif