Using the GNU Compiler Collection (GCC): PowerPC Built-in Functions

6.59.20 PowerPC Built-in Functions

The following built-in functions are always available and can be used to check the PowerPC target platform type:

Built-in Function: void __builtin_cpu_init (void): This function is a nop on the PowerPC platform and is included solely to maintain API compatibility with the x86 builtins.

Built-in Function: int __builtin_cpu_is (const char *cpuname)

This function returns a value of 1 if the run-time CPU is of type cpuname and returns 0 otherwise. The following CPU names can be detected:

‘power9’: IBM POWER9 Server CPU.
‘power8’: IBM POWER8 Server CPU.
‘power7’: IBM POWER7 Server CPU.
‘power6x’: IBM POWER6 Server CPU (RAW mode).
‘power6’: IBM POWER6 Server CPU (Architected mode).
‘power5+’: IBM POWER5+ Server CPU.
‘power5’: IBM POWER5 Server CPU.
‘ppc970’: IBM 970 Server CPU (ie, Apple G5).
‘power4’: IBM POWER4 Server CPU.
‘ppca2’: IBM A2 64-bit Embedded CPU
‘ppc476’: IBM PowerPC 476FP 32-bit Embedded CPU.
‘ppc464’: IBM PowerPC 464 32-bit Embedded CPU.
‘ppc440’: PowerPC 440 32-bit Embedded CPU.
‘ppc405’: PowerPC 405 32-bit Embedded CPU.
‘ppc-cell-be’: IBM PowerPC Cell Broadband Engine Architecture CPU.

Here is an example:

if (__builtin_cpu_is ("power8"))
  {
     do_power8 (); // POWER8 specific implementation.
  }
else
  {
     do_generic (); // Generic implementation.
  }

Built-in Function: int __builtin_cpu_supports (const char *feature)

This function returns a value of 1 if the run-time CPU supports the HWCAP feature feature and returns 0 otherwise. The following features can be detected:

‘4xxmac’: 4xx CPU has a Multiply Accumulator.
‘altivec’: CPU has a SIMD/Vector Unit.
‘arch_2_05’: CPU supports ISA 2.05 (eg, POWER6)
‘arch_2_06’: CPU supports ISA 2.06 (eg, POWER7)
‘arch_2_07’: CPU supports ISA 2.07 (eg, POWER8)
‘arch_3_00’: CPU supports ISA 3.00 (eg, POWER9)
‘archpmu’: CPU supports the set of compatible performance monitoring events.
‘booke’: CPU supports the Embedded ISA category.
‘cellbe’: CPU has a CELL broadband engine.
‘dfp’: CPU has a decimal floating point unit.
‘dscr’: CPU supports the data stream control register.
‘ebb’: CPU supports event base branching.
‘efpdouble’: CPU has a SPE double precision floating point unit.
‘efpsingle’: CPU has a SPE single precision floating point unit.
‘fpu’: CPU has a floating point unit.
‘htm’: CPU has hardware transaction memory instructions.
‘htm-nosc’: Kernel aborts hardware transactions when a syscall is made.
‘ic_snoop’: CPU supports icache snooping capabilities.
‘ieee128’: CPU supports 128-bit IEEE binary floating point instructions.
‘isel’: CPU supports the integer select instruction.
‘mmu’: CPU has a memory management unit.
‘notb’: CPU does not have a timebase (eg, 601 and 403gx).
‘pa6t’: CPU supports the PA Semi 6T CORE ISA.
‘power4’: CPU supports ISA 2.00 (eg, POWER4)
‘power5’: CPU supports ISA 2.02 (eg, POWER5)
‘power5+’: CPU supports ISA 2.03 (eg, POWER5+)
‘power6x’: CPU supports ISA 2.05 (eg, POWER6) extended opcodes mffgpr and mftgpr.
‘ppc32’: CPU supports 32-bit mode execution.
‘ppc601’: CPU supports the old POWER ISA (eg, 601)
‘ppc64’: CPU supports 64-bit mode execution.
‘ppcle’: CPU supports a little-endian mode that uses address swizzling.
‘smt’: CPU support simultaneous multi-threading.
‘spe’: CPU has a signal processing extension unit.
‘tar’: CPU supports the target address register.
‘true_le’: CPU supports true little-endian mode.
‘ucache’: CPU has unified I/D cache.
‘vcrypto’: CPU supports the vector cryptography instructions.
‘vsx’: CPU supports the vector-scalar extension.

Here is an example:

if (__builtin_cpu_supports ("fpu"))
  {
     asm("fadd %0,%1,%2" : "=d"(dst) : "d"(src1), "d"(src2));
  }
else
  {
     dst = __fadd (src1, src2); // Software FP addition function.
  }

These built-in functions are available for the PowerPC family of processors:

float __builtin_recipdivf (float, float);
float __builtin_rsqrtf (float);
double __builtin_recipdiv (double, double);
double __builtin_rsqrt (double);
uint64_t __builtin_ppc_get_timebase ();
unsigned long __builtin_ppc_mftb ();
double __builtin_unpack_longdouble (long double, int);
long double __builtin_pack_longdouble (double, double);

The vec_rsqrt, __builtin_rsqrt, and __builtin_rsqrtf functions generate multiple instructions to implement the reciprocal sqrt functionality using reciprocal sqrt estimate instructions.

The __builtin_recipdiv, and __builtin_recipdivf functions generate multiple instructions to implement division using the reciprocal estimate instructions.

The __builtin_ppc_get_timebase and __builtin_ppc_mftb functions generate instructions to read the Time Base Register. The __builtin_ppc_get_timebase function may generate multiple instructions and always returns the 64 bits of the Time Base Register. The __builtin_ppc_mftb function always generates one instruction and returns the Time Base Register value as an unsigned long, throwing away the most significant word on 32-bit environments.

Additional built-in functions are available for the 64-bit PowerPC family of processors, for efficient use of 128-bit floating point (__float128) values.

The following floating-point built-in functions are available with -mfloat128 and Altivec support. All of them implement the function that is part of the name.

__float128 __builtin_fabsq (__float128)
__float128 __builtin_copysignq (__float128, __float128)

The following built-in functions are available with -mfloat128 and Altivec support.

__float128 __builtin_infq (void): Similar to __builtin_inf, except the return type is __float128.
__float128 __builtin_huge_valq (void): Similar to __builtin_huge_val, except the return type is __float128.
__float128 __builtin_nanq (void): Similar to __builtin_nan, except the return type is __float128.
__float128 __builtin_nansq (void): Similar to __builtin_nans, except the return type is __float128.

The following built-in functions are available for the PowerPC family of processors, starting with ISA 2.06 or later (-mcpu=power7 or -mpopcntd):

long __builtin_bpermd (long, long);
int __builtin_divwe (int, int);
int __builtin_divweo (int, int);
unsigned int __builtin_divweu (unsigned int, unsigned int);
unsigned int __builtin_divweuo (unsigned int, unsigned int);
long __builtin_divde (long, long);
long __builtin_divdeo (long, long);
unsigned long __builtin_divdeu (unsigned long, unsigned long);
unsigned long __builtin_divdeuo (unsigned long, unsigned long);
unsigned int cdtbcd (unsigned int);
unsigned int cbcdtd (unsigned int);
unsigned int addg6s (unsigned int, unsigned int);

The __builtin_divde, __builtin_divdeo, __builtin_divdeu, __builtin_divdeou functions require a 64-bit environment support ISA 2.06 or later.

The following built-in functions are available for the PowerPC family of processors, starting with ISA 3.0 or later (-mcpu=power9):

long long __builtin_darn (void);
long long __builtin_darn_raw (void);
int __builtin_darn_32 (void);

int __builtin_dfp_dtstsfi_lt (unsigned int comparison, _Decimal64 value);
int __builtin_dfp_dtstsfi_lt (unsigned int comparison, _Decimal128 value);
int __builtin_dfp_dtstsfi_lt_dd (unsigned int comparison, _Decimal64 value);
int __builtin_dfp_dtstsfi_lt_td (unsigned int comparison, _Decimal128 value);

int __builtin_dfp_dtstsfi_gt (unsigned int comparison, _Decimal64 value);
int __builtin_dfp_dtstsfi_gt (unsigned int comparison, _Decimal128 value);
int __builtin_dfp_dtstsfi_gt_dd (unsigned int comparison, _Decimal64 value);
int __builtin_dfp_dtstsfi_gt_td (unsigned int comparison, _Decimal128 value);

int __builtin_dfp_dtstsfi_eq (unsigned int comparison, _Decimal64 value);
int __builtin_dfp_dtstsfi_eq (unsigned int comparison, _Decimal128 value);
int __builtin_dfp_dtstsfi_eq_dd (unsigned int comparison, _Decimal64 value);
int __builtin_dfp_dtstsfi_eq_td (unsigned int comparison, _Decimal128 value);

int __builtin_dfp_dtstsfi_ov (unsigned int comparison, _Decimal64 value);
int __builtin_dfp_dtstsfi_ov (unsigned int comparison, _Decimal128 value);
int __builtin_dfp_dtstsfi_ov_dd (unsigned int comparison, _Decimal64 value);
int __builtin_dfp_dtstsfi_ov_td (unsigned int comparison, _Decimal128 value);

The __builtin_darn and __builtin_darn_raw functions require a 64-bit environment supporting ISA 3.0 or later. The __builtin_darn function provides a 64-bit conditioned random number. The __builtin_darn_raw function provides a 64-bit raw random number. The __builtin_darn_32 function provides a 32-bit random number.

The __builtin_dfp_dtstsfi_lt function returns a non-zero value if and only if the number of signficant digits of its value argument is less than its comparison argument. The __builtin_dfp_dtstsfi_lt_dd and __builtin_dfp_dtstsfi_lt_td functions behave similarly, but require that the type of the value argument be __Decimal64 and __Decimal128 respectively.

The __builtin_dfp_dtstsfi_gt function returns a non-zero value if and only if the number of signficant digits of its value argument is greater than its comparison argument. The __builtin_dfp_dtstsfi_gt_dd and __builtin_dfp_dtstsfi_gt_td functions behave similarly, but require that the type of the value argument be __Decimal64 and __Decimal128 respectively.

The __builtin_dfp_dtstsfi_eq function returns a non-zero value if and only if the number of signficant digits of its value argument equals its comparison argument. The __builtin_dfp_dtstsfi_eq_dd and __builtin_dfp_dtstsfi_eq_td functions behave similarly, but require that the type of the value argument be __Decimal64 and __Decimal128 respectively.

The __builtin_dfp_dtstsfi_ov function returns a non-zero value if and only if its value argument has an undefined number of significant digits, such as when value is an encoding of NaN. The __builtin_dfp_dtstsfi_ov_dd and __builtin_dfp_dtstsfi_ov_td functions behave similarly, but require that the type of the value argument be __Decimal64 and __Decimal128 respectively.

The following built-in functions are available for the PowerPC family of processors when hardware decimal floating point (-mhard-dfp) is available:

_Decimal64 __builtin_dxex (_Decimal64);
_Decimal128 __builtin_dxexq (_Decimal128);
_Decimal64 __builtin_ddedpd (int, _Decimal64);
_Decimal128 __builtin_ddedpdq (int, _Decimal128);
_Decimal64 __builtin_denbcd (int, _Decimal64);
_Decimal128 __builtin_denbcdq (int, _Decimal128);
_Decimal64 __builtin_diex (_Decimal64, _Decimal64);
_Decimal128 _builtin_diexq (_Decimal128, _Decimal128);
_Decimal64 __builtin_dscli (_Decimal64, int);
_Decimal128 __builtin_dscliq (_Decimal128, int);
_Decimal64 __builtin_dscri (_Decimal64, int);
_Decimal128 __builtin_dscriq (_Decimal128, int);
unsigned long long __builtin_unpack_dec128 (_Decimal128, int);
_Decimal128 __builtin_pack_dec128 (unsigned long long, unsigned long long);

The following built-in functions are available for the PowerPC family of processors when the Vector Scalar (vsx) instruction set is available:

unsigned long long __builtin_unpack_vector_int128 (vector __int128_t, int);
vector __int128_t __builtin_pack_vector_int128 (unsigned long long,
                                                unsigned long long);