; Options for the IA-32 and AMD64 ports of the compiler. ; Copyright (C) 2005-2014 Free Software Foundation, Inc. ; ; This file is part of GCC. ; ; GCC is free software; you can redistribute it and/or modify it under ; the terms of the GNU General Public License as published by the Free ; Software Foundation; either version 3, or (at your option) any later ; version. ; ; GCC is distributed in the hope that it will be useful, but WITHOUT ANY ; WARRANTY; without even the implied warranty of MERCHANTABILITY or ; FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License ; for more details. ; ; You should have received a copy of the GNU General Public License ; along with GCC; see the file COPYING3. If not see ; . HeaderInclude config/i386/i386-opts.h ; Bit flags that specify the ISA we are compiling for. Variable HOST_WIDE_INT ix86_isa_flags = TARGET_64BIT_DEFAULT | TARGET_SUBTARGET_ISA_DEFAULT ; A mask of ix86_isa_flags that includes bit X if X was set or cleared ; on the command line. Variable HOST_WIDE_INT ix86_isa_flags_explicit TargetVariable int recip_mask = RECIP_MASK_DEFAULT Variable int recip_mask_explicit TargetSave int x_recip_mask_explicit ;; Definitions to add to the cl_target_option structure ;; -march= processor TargetSave unsigned char arch ;; -mtune= processor TargetSave unsigned char tune ;; -march= processor-string TargetSave const char *x_ix86_arch_string ;; -mtune= processor-string TargetSave const char *x_ix86_tune_string ;; CPU schedule model TargetSave unsigned char schedule ;; branch cost TargetSave unsigned char branch_cost ;; which flags were passed by the user TargetSave HOST_WIDE_INT x_ix86_isa_flags_explicit ;; which flags were passed by the user Variable int ix86_target_flags_explicit ;; which flags were passed by the user TargetSave HOST_WIDE_INT x_ix86_target_flags_explicit ;; whether -mtune was not specified TargetSave unsigned char tune_defaulted ;; whether -march was specified TargetSave unsigned char arch_specified ;; -mcmodel= model TargetSave enum cmodel x_ix86_cmodel ;; -mabi= TargetSave enum calling_abi x_ix86_abi ;; -masm= TargetSave enum asm_dialect x_ix86_asm_dialect ;; -mbranch-cost= TargetSave int x_ix86_branch_cost ;; -mdump-tune-features= TargetSave int x_ix86_dump_tunes ;; -mstackrealign= TargetSave int x_ix86_force_align_arg_pointer ;; -mforce-drap= TargetSave int x_ix86_force_drap ;; -mincoming-stack-boundary= TargetSave int x_ix86_incoming_stack_boundary_arg ;; -maddress-mode= TargetSave enum pmode x_ix86_pmode ;; -mpreferred-stack-boundary= TargetSave int x_ix86_preferred_stack_boundary_arg ;; -mrecip= TargetSave const char *x_ix86_recip_name ;; -mregparm= TargetSave int x_ix86_regparm ;; -mlarge-data-threshold= TargetSave int x_ix86_section_threshold ;; -msse2avx= TargetSave int x_ix86_sse2avx ;; -mstack-protector-guard= TargetSave enum stack_protector_guard x_ix86_stack_protector_guard ;; -mstringop-strategy= TargetSave enum stringop_alg x_ix86_stringop_alg ;; -mtls-dialect= TargetSave enum tls_dialect x_ix86_tls_dialect ;; -mtune-ctrl= TargetSave const char *x_ix86_tune_ctrl_string ;; -mmemcpy-strategy= TargetSave const char *x_ix86_tune_memcpy_strategy ;; -mmemset-strategy= TargetSave const char *x_ix86_tune_memset_strategy ;; -mno-default= TargetSave int x_ix86_tune_no_default ;; -mveclibabi= TargetSave enum ix86_veclibabi x_ix86_veclibabi_type ;; x86 options m128bit-long-double Target RejectNegative Report Mask(128BIT_LONG_DOUBLE) Save sizeof(long double) is 16 m80387 Target Report Mask(80387) Save Use hardware fp m96bit-long-double Target RejectNegative Report InverseMask(128BIT_LONG_DOUBLE) Save sizeof(long double) is 12 mlong-double-80 Target Report RejectNegative Negative(mlong-double-64) InverseMask(LONG_DOUBLE_64) Save Use 80-bit long double mlong-double-64 Target Report RejectNegative Negative(mlong-double-128) Mask(LONG_DOUBLE_64) InverseMask(LONG_DOUBLE_128) Save Use 64-bit long double mlong-double-128 Target Report RejectNegative Negative(mlong-double-80) Mask(LONG_DOUBLE_128) InverseMask(LONG_DOUBLE_64) Save Use 128-bit long double maccumulate-outgoing-args Target Report Mask(ACCUMULATE_OUTGOING_ARGS) Save Reserve space for outgoing arguments in the function prologue malign-double Target Report Mask(ALIGN_DOUBLE) Save Align some doubles on dword boundary malign-functions= Target RejectNegative Joined UInteger Function starts are aligned to this power of 2 malign-jumps= Target RejectNegative Joined UInteger Jump targets are aligned to this power of 2 malign-loops= Target RejectNegative Joined UInteger Loop code aligned to this power of 2 malign-stringops Target RejectNegative Report InverseMask(NO_ALIGN_STRINGOPS, ALIGN_STRINGOPS) Save Align destination of the string operations march= Target RejectNegative Joined Var(ix86_arch_string) Generate code for given CPU masm= Target RejectNegative Joined Enum(asm_dialect) Var(ix86_asm_dialect) Init(ASM_ATT) Use given assembler dialect Enum Name(asm_dialect) Type(enum asm_dialect) Known assembler dialects (for use with the -masm-dialect= option): EnumValue Enum(asm_dialect) String(intel) Value(ASM_INTEL) EnumValue Enum(asm_dialect) String(att) Value(ASM_ATT) mbranch-cost= Target RejectNegative Joined UInteger Var(ix86_branch_cost) Branches are this expensive (1-5, arbitrary units) mlarge-data-threshold= Target RejectNegative Joined UInteger Var(ix86_section_threshold) Init(DEFAULT_LARGE_SECTION_THRESHOLD) Data greater than given threshold will go into .ldata section in x86-64 medium model mcmodel= Target RejectNegative Joined Enum(cmodel) Var(ix86_cmodel) Init(CM_32) Use given x86-64 code model Enum Name(cmodel) Type(enum cmodel) Known code models (for use with the -mcmodel= option): EnumValue Enum(cmodel) String(small) Value(CM_SMALL) EnumValue Enum(cmodel) String(medium) Value(CM_MEDIUM) EnumValue Enum(cmodel) String(large) Value(CM_LARGE) EnumValue Enum(cmodel) String(32) Value(CM_32) EnumValue Enum(cmodel) String(kernel) Value(CM_KERNEL) maddress-mode= Target RejectNegative Joined Enum(pmode) Var(ix86_pmode) Init(PMODE_SI) Use given address mode Enum Name(pmode) Type(enum pmode) Known address mode (for use with the -maddress-mode= option): EnumValue Enum(pmode) String(short) Value(PMODE_SI) EnumValue Enum(pmode) String(long) Value(PMODE_DI) mcpu= Target RejectNegative Joined Undocumented Alias(mtune=) Warn(%<-mcpu=%> is deprecated; use %<-mtune=%> or %<-march=%> instead) mfancy-math-387 Target RejectNegative Report InverseMask(NO_FANCY_MATH_387, USE_FANCY_MATH_387) Save Generate sin, cos, sqrt for FPU mforce-drap Target Report Var(ix86_force_drap) Always use Dynamic Realigned Argument Pointer (DRAP) to realign stack mfp-ret-in-387 Target Report Mask(FLOAT_RETURNS) Save Return values of functions in FPU registers mfpmath= Target RejectNegative Joined Var(ix86_fpmath) Enum(fpmath_unit) Init(FPMATH_387) Save Generate floating point mathematics using given instruction set Enum Name(fpmath_unit) Type(enum fpmath_unit) Valid arguments to -mfpmath=: EnumValue Enum(fpmath_unit) String(387) Value(FPMATH_387) EnumValue Enum(fpmath_unit) String(sse) Value(FPMATH_SSE) EnumValue Enum(fpmath_unit) String(387,sse) Value({(enum fpmath_unit) (FPMATH_SSE | FPMATH_387)}) EnumValue Enum(fpmath_unit) String(387+sse) Value({(enum fpmath_unit) (FPMATH_SSE | FPMATH_387)}) EnumValue Enum(fpmath_unit) String(sse,387) Value({(enum fpmath_unit) (FPMATH_SSE | FPMATH_387)}) EnumValue Enum(fpmath_unit) String(sse+387) Value({(enum fpmath_unit) (FPMATH_SSE | FPMATH_387)}) EnumValue Enum(fpmath_unit) String(both) Value({(enum fpmath_unit) (FPMATH_SSE | FPMATH_387)}) mhard-float Target RejectNegative Mask(80387) Save Use hardware fp mieee-fp Target Report Mask(IEEE_FP) Save Use IEEE math for fp comparisons minline-all-stringops Target Report Mask(INLINE_ALL_STRINGOPS) Save Inline all known string operations minline-stringops-dynamically Target Report Mask(INLINE_STRINGOPS_DYNAMICALLY) Save Inline memset/memcpy string operations, but perform inline version only for small blocks mintel-syntax Target Undocumented Alias(masm=, intel, att) Warn(%<-mintel-syntax%> and %<-mno-intel-syntax%> are deprecated; use %<-masm=intel%> and %<-masm=att%> instead) ;; Deprecated mms-bitfields Target Report Mask(MS_BITFIELD_LAYOUT) Save Use native (MS) bitfield layout mno-align-stringops Target RejectNegative Report Mask(NO_ALIGN_STRINGOPS) Undocumented Save mno-fancy-math-387 Target RejectNegative Report Mask(NO_FANCY_MATH_387) Undocumented Save mno-push-args Target RejectNegative Report Mask(NO_PUSH_ARGS) Undocumented Save mno-red-zone Target RejectNegative Report Mask(NO_RED_ZONE) Undocumented Save momit-leaf-frame-pointer Target Report Mask(OMIT_LEAF_FRAME_POINTER) Save Omit the frame pointer in leaf functions mpc32 Target RejectNegative Report Set 80387 floating-point precision to 32-bit mpc64 Target RejectNegative Report Set 80387 floating-point precision to 64-bit mpc80 Target RejectNegative Report Set 80387 floating-point precision to 80-bit mpreferred-stack-boundary= Target RejectNegative Joined UInteger Var(ix86_preferred_stack_boundary_arg) Attempt to keep stack aligned to this power of 2 mincoming-stack-boundary= Target RejectNegative Joined UInteger Var(ix86_incoming_stack_boundary_arg) Assume incoming stack aligned to this power of 2 mpush-args Target Report InverseMask(NO_PUSH_ARGS, PUSH_ARGS) Save Use push instructions to save outgoing arguments mred-zone Target RejectNegative Report InverseMask(NO_RED_ZONE, RED_ZONE) Save Use red-zone in the x86-64 code mregparm= Target RejectNegative Joined UInteger Var(ix86_regparm) Number of registers used to pass integer arguments mrtd Target Report Mask(RTD) Save Alternate calling convention msoft-float Target InverseMask(80387) Save Do not use hardware fp msseregparm Target RejectNegative Mask(SSEREGPARM) Save Use SSE register passing conventions for SF and DF mode mstackrealign Target Report Var(ix86_force_align_arg_pointer) Init(-1) Realign stack in prologue mstack-arg-probe Target Report Mask(STACK_PROBE) Save Enable stack probing mmemcpy-strategy= Target RejectNegative Joined Var(ix86_tune_memcpy_strategy) Specify memcpy expansion strategy when expected size is known mmemset-strategy= Target RejectNegative Joined Var(ix86_tune_memset_strategy) Specify memset expansion strategy when expected size is known mstringop-strategy= Target RejectNegative Joined Enum(stringop_alg) Var(ix86_stringop_alg) Init(no_stringop) Chose strategy to generate stringop using Enum Name(stringop_alg) Type(enum stringop_alg) Valid arguments to -mstringop-strategy=: EnumValue Enum(stringop_alg) String(rep_byte) Value(rep_prefix_1_byte) EnumValue Enum(stringop_alg) String(libcall) Value(libcall) EnumValue Enum(stringop_alg) String(rep_4byte) Value(rep_prefix_4_byte) EnumValue Enum(stringop_alg) String(rep_8byte) Value(rep_prefix_8_byte) EnumValue Enum(stringop_alg) String(byte_loop) Value(loop_1_byte) EnumValue Enum(stringop_alg) String(loop) Value(loop) EnumValue Enum(stringop_alg) String(unrolled_loop) Value(unrolled_loop) EnumValue Enum(stringop_alg) String(vector_loop) Value(vector_loop) mtls-dialect= Target RejectNegative Joined Var(ix86_tls_dialect) Enum(tls_dialect) Init(TLS_DIALECT_GNU) Use given thread-local storage dialect Enum Name(tls_dialect) Type(enum tls_dialect) Known TLS dialects (for use with the -mtls-dialect= option): EnumValue Enum(tls_dialect) String(gnu) Value(TLS_DIALECT_GNU) EnumValue Enum(tls_dialect) String(gnu2) Value(TLS_DIALECT_GNU2) mtls-direct-seg-refs Target Report Mask(TLS_DIRECT_SEG_REFS) Use direct references against %gs when accessing tls data mtune= Target RejectNegative Joined Var(ix86_tune_string) Schedule code for given CPU mtune-ctrl= Target RejectNegative Joined Var(ix86_tune_ctrl_string) Fine grain control of tune features mno-default Target RejectNegative Var(ix86_tune_no_default) Init(0) Clear all tune features mdump-tune-features Target RejectNegative Var(ix86_dump_tunes) Init(0) mabi= Target RejectNegative Joined Var(ix86_abi) Enum(calling_abi) Init(SYSV_ABI) Generate code that conforms to the given ABI Enum Name(calling_abi) Type(enum calling_abi) Known ABIs (for use with the -mabi= option): EnumValue Enum(calling_abi) String(sysv) Value(SYSV_ABI) EnumValue Enum(calling_abi) String(ms) Value(MS_ABI) mveclibabi= Target RejectNegative Joined Var(ix86_veclibabi_type) Enum(ix86_veclibabi) Init(ix86_veclibabi_type_none) Vector library ABI to use Enum Name(ix86_veclibabi) Type(enum ix86_veclibabi) Known vectorization library ABIs (for use with the -mveclibabi= option): EnumValue Enum(ix86_veclibabi) String(svml) Value(ix86_veclibabi_type_svml) EnumValue Enum(ix86_veclibabi) String(acml) Value(ix86_veclibabi_type_acml) mvect8-ret-in-mem Target Report Mask(VECT8_RETURNS) Save Return 8-byte vectors in memory mrecip Target Report Mask(RECIP) Save Generate reciprocals instead of divss and sqrtss. mrecip= Target Report RejectNegative Joined Var(ix86_recip_name) Control generation of reciprocal estimates. mcld Target Report Mask(CLD) Save Generate cld instruction in the function prologue. mvzeroupper Target Report Mask(VZEROUPPER) Save Generate vzeroupper instruction before a transfer of control flow out of the function. mdispatch-scheduler Target RejectNegative Var(flag_dispatch_scheduler) Do dispatch scheduling if processor is bdver1 or bdver2 or bdver3 or bdver4 and Haifa scheduling is selected. mprefer-avx128 Target Report Mask(PREFER_AVX128) SAVE Use 128-bit AVX instructions instead of 256-bit AVX instructions in the auto-vectorizer. ;; ISA support m32 Target RejectNegative Negative(m64) Report InverseMask(ISA_64BIT) Var(ix86_isa_flags) Save Generate 32bit i386 code m64 Target RejectNegative Negative(mx32) Report Mask(ABI_64) Var(ix86_isa_flags) Save Generate 64bit x86-64 code mx32 Target RejectNegative Negative(m16) Report Mask(ABI_X32) Var(ix86_isa_flags) Save Generate 32bit x86-64 code m16 Target RejectNegative Negative(m32) Report Mask(CODE16) InverseMask(ISA_64BIT) Var(ix86_isa_flags) Save Generate 16bit i386 code mmmx Target Report Mask(ISA_MMX) Var(ix86_isa_flags) Save Support MMX built-in functions m3dnow Target Report Mask(ISA_3DNOW) Var(ix86_isa_flags) Save Support 3DNow! built-in functions m3dnowa Target Undocumented Mask(ISA_3DNOW_A) Var(ix86_isa_flags) Save Support Athlon 3Dnow! built-in functions msse Target Report Mask(ISA_SSE) Var(ix86_isa_flags) Save Support MMX and SSE built-in functions and code generation msse2 Target Report Mask(ISA_SSE2) Var(ix86_isa_flags) Save Support MMX, SSE and SSE2 built-in functions and code generation msse3 Target Report Mask(ISA_SSE3) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2 and SSE3 built-in functions and code generation mssse3 Target Report Mask(ISA_SSSE3) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3 and SSSE3 built-in functions and code generation msse4.1 Target Report Mask(ISA_SSE4_1) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3, SSSE3 and SSE4.1 built-in functions and code generation msse4.2 Target Report Mask(ISA_SSE4_2) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1 and SSE4.2 built-in functions and code generation msse4 Target RejectNegative Report Mask(ISA_SSE4_2) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1 and SSE4.2 built-in functions and code generation mno-sse4 Target RejectNegative Report InverseMask(ISA_SSE4_1) Var(ix86_isa_flags) Save Do not support SSE4.1 and SSE4.2 built-in functions and code generation msse5 Target Undocumented Alias(mavx) Warn(%<-msse5%> was removed) ;; Deprecated mavx Target Report Mask(ISA_AVX) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2 and AVX built-in functions and code generation mavx2 Target Report Mask(ISA_AVX2) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AVX and AVX2 built-in functions and code generation mavx512f Target Report Mask(ISA_AVX512F) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AVX, AVX2 and AVX512F built-in functions and code generation mavx512pf Target Report Mask(ISA_AVX512PF) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AVX, AVX2 and AVX512F and AVX512PF built-in functions and code generation mavx512er Target Report Mask(ISA_AVX512ER) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AVX, AVX2 and AVX512F and AVX512ER built-in functions and code generation mavx512cd Target Report Mask(ISA_AVX512CD) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AVX, AVX2 and AVX512F and AVX512CD built-in functions and code generation mfma Target Report Mask(ISA_FMA) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AVX and FMA built-in functions and code generation msse4a Target Report Mask(ISA_SSE4A) Var(ix86_isa_flags) Save Support MMX, SSE, SSE2, SSE3 and SSE4A built-in functions and code generation mfma4 Target Report Mask(ISA_FMA4) Var(ix86_isa_flags) Save Support FMA4 built-in functions and code generation mxop Target Report Mask(ISA_XOP) Var(ix86_isa_flags) Save Support XOP built-in functions and code generation mlwp Target Report Mask(ISA_LWP) Var(ix86_isa_flags) Save Support LWP built-in functions and code generation mabm Target Report Mask(ISA_ABM) Var(ix86_isa_flags) Save Support code generation of Advanced Bit Manipulation (ABM) instructions. mpopcnt Target Report Mask(ISA_POPCNT) Var(ix86_isa_flags) Save Support code generation of popcnt instruction. mbmi Target Report Mask(ISA_BMI) Var(ix86_isa_flags) Save Support BMI built-in functions and code generation mbmi2 Target Report Mask(ISA_BMI2) Var(ix86_isa_flags) Save Support BMI2 built-in functions and code generation mlzcnt Target Report Mask(ISA_LZCNT) Var(ix86_isa_flags) Save Support LZCNT built-in function and code generation mhle Target Report Mask(ISA_HLE) Var(ix86_isa_flags) Save Support Hardware Lock Elision prefixes mrdseed Target Report Mask(ISA_RDSEED) Var(ix86_isa_flags) Save Support RDSEED instruction mprfchw Target Report Mask(ISA_PRFCHW) Var(ix86_isa_flags) Save Support PREFETCHW instruction madx Target Report Mask(ISA_ADX) Var(ix86_isa_flags) Save Support flag-preserving add-carry instructions mfxsr Target Report Mask(ISA_FXSR) Var(ix86_isa_flags) Save Support FXSAVE and FXRSTOR instructions mxsave Target Report Mask(ISA_XSAVE) Var(ix86_isa_flags) Save Support XSAVE and XRSTOR instructions mxsaveopt Target Report Mask(ISA_XSAVEOPT) Var(ix86_isa_flags) Save Support XSAVEOPT instruction mtbm Target Report Mask(ISA_TBM) Var(ix86_isa_flags) Save Support TBM built-in functions and code generation mcx16 Target Report Mask(ISA_CX16) Var(ix86_isa_flags) Save Support code generation of cmpxchg16b instruction. msahf Target Report Mask(ISA_SAHF) Var(ix86_isa_flags) Save Support code generation of sahf instruction in 64bit x86-64 code. mmovbe Target Report Mask(ISA_MOVBE) Var(ix86_isa_flags) Save Support code generation of movbe instruction. mcrc32 Target Report Mask(ISA_CRC32) Var(ix86_isa_flags) Save Support code generation of crc32 instruction. maes Target Report Mask(ISA_AES) Var(ix86_isa_flags) Save Support AES built-in functions and code generation msha Target Report Mask(ISA_SHA) Var(ix86_isa_flags) Save Support SHA1 and SHA256 built-in functions and code generation mpclmul Target Report Mask(ISA_PCLMUL) Var(ix86_isa_flags) Save Support PCLMUL built-in functions and code generation msse2avx Target Report Var(ix86_sse2avx) Encode SSE instructions with VEX prefix mfsgsbase Target Report Mask(ISA_FSGSBASE) Var(ix86_isa_flags) Save Support FSGSBASE built-in functions and code generation mrdrnd Target Report Mask(ISA_RDRND) Var(ix86_isa_flags) Save Support RDRND built-in functions and code generation mf16c Target Report Mask(ISA_F16C) Var(ix86_isa_flags) Save Support F16C built-in functions and code generation mprefetchwt1 Target Report Mask(ISA_PREFETCHWT1) Var(ix86_isa_flags) Save Support PREFETCHWT1 built-in functions and code generation mfentry Target Report Var(flag_fentry) Init(-1) Emit profiling counter call at function entry before prologue. m8bit-idiv Target Report Mask(USE_8BIT_IDIV) Save Expand 32bit/64bit integer divide into 8bit unsigned integer divide with run-time check mavx256-split-unaligned-load Target Report Mask(AVX256_SPLIT_UNALIGNED_LOAD) Save Split 32-byte AVX unaligned load mavx256-split-unaligned-store Target Report Mask(AVX256_SPLIT_UNALIGNED_STORE) Save Split 32-byte AVX unaligned store mrtm Target Report Mask(ISA_RTM) Var(ix86_isa_flags) Save Support RTM built-in functions and code generation mstack-protector-guard= Target RejectNegative Joined Enum(stack_protector_guard) Var(ix86_stack_protector_guard) Init(SSP_TLS) Use given stack-protector guard Enum Name(stack_protector_guard) Type(enum stack_protector_guard) Known stack protector guard (for use with the -mstack-protector-guard= option): EnumValue Enum(stack_protector_guard) String(tls) Value(SSP_TLS) EnumValue Enum(stack_protector_guard) String(global) Value(SSP_GLOBAL) mindirect-branch= Target Report RejectNegative Joined Enum(indirect_branch) Var(ix86_indirect_branch) Init(indirect_branch_keep) Convert indirect call and jump to call and return thunks. mfunction-return= Target Report RejectNegative Joined Enum(indirect_branch) Var(ix86_function_return) Init(indirect_branch_keep) Convert function return to call and return thunk. Enum Name(indirect_branch) Type(enum indirect_branch) Known indirect branch choices (for use with the -mindirect-branch=/-mfunction-return= options): EnumValue Enum(indirect_branch) String(keep) Value(indirect_branch_keep) EnumValue Enum(indirect_branch) String(thunk) Value(indirect_branch_thunk) EnumValue Enum(indirect_branch) String(thunk-inline) Value(indirect_branch_thunk_inline) EnumValue Enum(indirect_branch) String(thunk-extern) Value(indirect_branch_thunk_extern) mindirect-branch-register Target Report Var(ix86_indirect_branch_register) Init(0) Force indirect call and jump via register.