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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 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.
#include "llvm/MC/MCTargetOptions.h"
namespace llvm {
class MachineFunction;
class Module;
namespace FloatABI {
enum ABIType {
Default, // Target-specific (either soft or hard depending on triple, etc).
Soft, // Soft float.
Hard // Hard float.
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
namespace FPDenormal {
enum DenormalMode {
IEEE, // IEEE 754 denormal numbers
PreserveSign, // the sign of a flushed-to-zero number is preserved in
// the sign of 0
PositiveZero // denormals are flushed to positive zero
enum class EABI {
Default, // Default means not specified
EABI4, // Target-specific (either 4, 5 or gnu depending on triple).
/// 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.
/// The "tuning" should be used to set defaults for individual feature flags
/// in DwarfDebug; if a given feature has a more specific command-line option,
/// that option should take precedence over the tuning.
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).
/// 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.
class TargetOptions {
: PrintMachineCode(false), UnsafeFPMath(false), NoInfsFPMath(false),
NoNaNsFPMath(false), NoTrappingFPMath(true),
HonorSignDependentRoundingFPMathOption(false), NoZerosInBSS(false),
GuaranteedTailCallOpt(false), StackSymbolOrdering(true),
EnableFastISel(false), EnableGlobalISel(false), UseInitArray(false),
DisableIntegratedAS(false), RelaxELFRelocations(false),
FunctionSections(false), DataSections(false),
UniqueSectionNames(true), TrapUnreachable(false),
NoTrapAfterNoreturn(false), TLSSize(0), EmulatedTLS(false),
ExplicitEmulatedTLS(false), EnableIPRA(false),
EmitStackSizeSection(false), EnableMachineOutliner(false),
SupportsDefaultOutlining(false), EmitAddrsig(false),
EnableDebugEntryValues(false), ForceDwarfFrameSection(false) {}
/// PrintMachineCode - This flag is enabled when the -print-machineinstrs
/// option is specified on the command line, and should enable debugging
/// output from the code generator.
unsigned PrintMachineCode : 1;
/// DisableFramePointerElim - This returns true if frame pointer elimination
/// optimization should be disabled for the given machine function.
bool DisableFramePointerElim(const MachineFunction &MF) const;
/// UnsafeFPMath - This flag is enabled when the
/// -enable-unsafe-fp-math flag is specified on the command line. When
/// this flag is off (the default), the code generator is not allowed to
/// produce results that are "less precise" than IEEE allows. This includes
/// use of X86 instructions like FSIN and FCOS instead of libcalls.
unsigned UnsafeFPMath : 1;
/// 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;
/// 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;
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;
/// StackAlignmentOverride - Override default stack alignment for target.
unsigned StackAlignmentOverride = 0;
/// 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;
/// UseInitArray - Use .init_array instead of .ctors for static
/// constructors.
unsigned UseInitArray : 1;
/// Disable the integrated assembler.
unsigned DisableIntegratedAS : 1;
/// Compress DWARF debug sections.
DebugCompressionType CompressDebugSections = DebugCompressionType::None;
unsigned RelaxELFRelocations : 1;
/// Emit functions into separate sections.
unsigned FunctionSections : 1;
/// Emit data into separate sections.
unsigned DataSections : 1;
unsigned UniqueSectionNames : 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;
/// Whether -emulated-tls or -no-emulated-tls is set.
unsigned ExplicitEmulatedTLS : 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;
/// Set if the target supports default outlining behaviour.
unsigned SupportsDefaultOutlining : 1;
/// Emit address-significance table.
unsigned EmitAddrsig : 1;
/// Emit debug info about parameter's entry values.
unsigned EnableDebugEntryValues : 1;
/// Emit DWARF debug frame section.
unsigned ForceDwarfFrameSection : 1;
/// 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 -fuse-fp-ops=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;
/// FPDenormalMode - This flags specificies which denormal numbers the code
/// is permitted to require.
FPDenormal::DenormalMode FPDenormalMode = FPDenormal::IEEE;
/// What exception model to use
ExceptionHandling ExceptionModel = ExceptionHandling::None;
/// Machine level options.
MCTargetOptions MCOptions;
} // End llvm namespace