ydb/contrib/libs/cxxsupp/builtins

Compiler-RT
================================

This directory and its subdirectories contain source code for the compiler
support routines.

Compiler-RT is open source software. You may freely distribute it under the
terms of the license agreement found in LICENSE.txt.

================================

This is a replacement library for libgcc. Each function is contained
in its own file. Each function has a corresponding unit test under
test/Unit.

A rudimentary script to test each file is in the file called
test/Unit/test.

Here is the specification for this library:

http://gcc.gnu.org/onlinedocs/gccint/Libgcc.html#Libgcc

Here is a synopsis of the contents of this library:

typedef int si_int;
typedef unsigned su_int;

typedef long long di_int;
typedef unsigned long long du_int;

// Integral bit manipulation

di_int __ashldi3(di_int a, si_int b); // a << b
ti_int __ashlti3(ti_int a, si_int b); // a << b

di_int __ashrdi3(di_int a, si_int b); // a >> b arithmetic (sign fill)
ti_int __ashrti3(ti_int a, si_int b); // a >> b arithmetic (sign fill)
di_int __lshrdi3(di_int a, si_int b); // a >> b logical (zero fill)
ti_int __lshrti3(ti_int a, si_int b); // a >> b logical (zero fill)

si_int __clzsi2(si_int a); // count leading zeros
si_int __clzdi2(di_int a); // count leading zeros
si_int __clzti2(ti_int a); // count leading zeros
si_int __ctzsi2(si_int a); // count trailing zeros
si_int __ctzdi2(di_int a); // count trailing zeros
si_int __ctzti2(ti_int a); // count trailing zeros

si_int __ffsdi2(di_int a); // find least significant 1 bit
si_int __ffsti2(ti_int a); // find least significant 1 bit

si_int __paritysi2(si_int a); // bit parity
si_int __paritydi2(di_int a); // bit parity
si_int __parityti2(ti_int a); // bit parity

si_int __popcountsi2(si_int a); // bit population
si_int __popcountdi2(di_int a); // bit population
si_int __popcountti2(ti_int a); // bit population

uint32_t __bswapsi2(uint32_t a); // a byteswapped, arm only
uint64_t __bswapdi2(uint64_t a); // a byteswapped, arm only

// Integral arithmetic

di_int __negdi2 (di_int a); // -a
ti_int __negti2 (ti_int a); // -a
di_int __muldi3 (di_int a, di_int b); // a * b
ti_int __multi3 (ti_int a, ti_int b); // a * b
si_int __divsi3 (si_int a, si_int b); // a / b signed
di_int __divdi3 (di_int a, di_int b); // a / b signed
ti_int __divti3 (ti_int a, ti_int b); // a / b signed
su_int __udivsi3 (su_int n, su_int d); // a / b unsigned
du_int __udivdi3 (du_int a, du_int b); // a / b unsigned
tu_int __udivti3 (tu_int a, tu_int b); // a / b unsigned
si_int __modsi3 (si_int a, si_int b); // a % b signed
di_int __moddi3 (di_int a, di_int b); // a % b signed
ti_int __modti3 (ti_int a, ti_int b); // a % b signed
su_int __umodsi3 (su_int a, su_int b); // a % b unsigned
du_int __umoddi3 (du_int a, du_int b); // a % b unsigned
tu_int __umodti3 (tu_int a, tu_int b); // a % b unsigned
du_int __udivmoddi4(du_int a, du_int b, du_int* rem); // a / b, *rem = a % b unsigned
tu_int __udivmodti4(tu_int a, tu_int b, tu_int* rem); // a / b, *rem = a % b unsigned
su_int __udivmodsi4(su_int a, su_int b, su_int* rem); // a / b, *rem = a % b unsigned
si_int __divmodsi4(si_int a, si_int b, si_int* rem); // a / b, *rem = a % b signed



// Integral arithmetic with trapping overflow

si_int __absvsi2(si_int a); // abs(a)
di_int __absvdi2(di_int a); // abs(a)
ti_int __absvti2(ti_int a); // abs(a)

si_int __negvsi2(si_int a); // -a
di_int __negvdi2(di_int a); // -a
ti_int __negvti2(ti_int a); // -a

si_int __addvsi3(si_int a, si_int b); // a + b
di_int __addvdi3(di_int a, di_int b); // a + b
ti_int __addvti3(ti_int a, ti_int b); // a + b

si_int __subvsi3(si_int a, si_int b); // a - b
di_int __subvdi3(di_int a, di_int b); // a - b
ti_int __subvti3(ti_int a, ti_int b); // a - b

si_int __mulvsi3(si_int a, si_int b); // a * b
di_int __mulvdi3(di_int a, di_int b); // a * b
ti_int __mulvti3(ti_int a, ti_int b); // a * b


// Integral arithmetic which returns if overflow

si_int __mulosi4(si_int a, si_int b, int* overflow); // a * b, overflow set to one if result not in signed range
di_int __mulodi4(di_int a, di_int b, int* overflow); // a * b, overflow set to one if result not in signed range
ti_int __muloti4(ti_int a, ti_int b, int* overflow); // a * b, overflow set to
one if result not in signed range


// Integral comparison: a < b -> 0
// a == b -> 1
// a > b -> 2

si_int __cmpdi2 (di_int a, di_int b);
si_int __cmpti2 (ti_int a, ti_int b);
si_int __ucmpdi2(du_int a, du_int b);
si_int __ucmpti2(tu_int a, tu_int b);

// Integral / floating point conversion

di_int __fixsfdi( float a);
di_int __fixdfdi( double a);
di_int __fixxfdi(long double a);

ti_int __fixsfti( float a);
ti_int __fixdfti( double a);
ti_int __fixxfti(long double a);
uint64_t __fixtfdi(long double input); // ppc only, doesn't match documentation

su_int __fixunssfsi( float a);
su_int __fixunsdfsi( double a);
su_int __fixunsxfsi(long double a);

du_int __fixunssfdi( float a);
du_int __fixunsdfdi( double a);
du_int __fixunsxfdi(long double a);

tu_int __fixunssfti( float a);
tu_int __fixunsdfti( double a);
tu_int __fixunsxfti(long double a);
uint64_t __fixunstfdi(long double input); // ppc only

float __floatdisf(di_int a);
double __floatdidf(di_int a);
long double __floatdixf(di_int a);
long double __floatditf(int64_t a); // ppc only

float __floattisf(ti_int a);
double __floattidf(ti_int a);
long double __floattixf(ti_int a);

float __floatundisf(du_int a);
double __floatundidf(du_int a);
long double __floatundixf(du_int a);
long double __floatunditf(uint64_t a); // ppc only

float __floatuntisf(tu_int a);
double __floatuntidf(tu_int a);
long double __floatuntixf(tu_int a);

// Floating point raised to integer power

float __powisf2( float a, si_int b); // a ^ b
double __powidf2( double a, si_int b); // a ^ b
long double __powixf2(long double a, si_int b); // a ^ b
long double __powitf2(long double a, si_int b); // ppc only, a ^ b

// Complex arithmetic

// (a + ib) * (c + id)

float _Complex __mulsc3( float a, float b, float c, float d);
double _Complex __muldc3(double a, double b, double c, double d);
long double _Complex __mulxc3(long double a, long double b,
long double c, long double d);
long double _Complex __multc3(long double a, long double b,
long double c, long double d); // ppc only

// (a + ib) / (c + id)

float _Complex __divsc3( float a, float b, float c, float d);
double _Complex __divdc3(double a, double b, double c, double d);
long double _Complex __divxc3(long double a, long double b,
long double c, long double d);
long double _Complex __divtc3(long double a, long double b,
long double c, long double d); // ppc only


// Runtime support

// __clear_cache() is used to tell process that new instructions have been
// written to an address range. Necessary on processors that do not have
// a unified instruction and data cache.
void __clear_cache(void* start, void* end);

// __enable_execute_stack() is used with nested functions when a trampoline
// function is written onto the stack and that page range needs to be made
// executable.
void __enable_execute_stack(void* addr);

// __gcc_personality_v0() is normally only called by the system unwinder.
// C code (as opposed to C++) normally does not need a personality function
// because there are no catch clauses or destructors to be run. But there
// is a C language extension __attribute__((cleanup(func))) which marks local
// variables as needing the cleanup function "func" to be run when the
// variable goes out of scope. That includes when an exception is thrown,
// so a personality handler is needed.
_Unwind_Reason_Code __gcc_personality_v0(int version, _Unwind_Action actions,
uint64_t exceptionClass, struct _Unwind_Exception* exceptionObject,
_Unwind_Context_t context);

// for use with some implementations of assert() in
void __eprintf(const char* format, const char* assertion_expression,
const char* line, const char* file);

// for systems with emulated thread local storage
void* __emutls_get_address(struct __emutls_control*);


// Power PC specific functions

// There is no C interface to the saveFP/restFP functions. They are helper
// functions called by the prolog and epilog of functions that need to save
// a number of non-volatile float point registers.
saveFP
restFP

// PowerPC has a standard template for trampoline functions. This function
// generates a custom trampoline function with the specific realFunc
// and localsPtr values.
void __trampoline_setup(uint32_t* trampOnStack, int trampSizeAllocated,
const void* realFunc, void* localsPtr);

// adds two 128-bit double-double precision values ( x + y )
long double __gcc_qadd(long double x, long double y);

// subtracts two 128-bit double-double precision values ( x - y )
long double __gcc_qsub(long double x, long double y);

// multiples two 128-bit double-double precision values ( x * y )
long double __gcc_qmul(long double x, long double y);

// divides two 128-bit double-double precision values ( x / y )
long double __gcc_qdiv(long double a, long double b);


// ARM specific functions

// There is no C interface to the switch* functions. These helper functions
// are only needed by Thumb1 code for efficient switch table generation.
switch16
switch32
switch8
switchu8

// There is no C interface to the *_vfp_d8_d15_regs functions. There are
// called in the prolog and epilog of Thumb1 functions. When the C++ ABI use
// SJLJ for exceptions, each function with a catch clause or destuctors needs
// to save and restore all registers in it prolog and epliog. But there is
// no way to access vector and high float registers from thumb1 code, so the
// compiler must add call outs to these helper functions in the prolog and
// epilog.
restore_vfp_d8_d15_regs
save_vfp_d8_d15_regs


// Note: long ago ARM processors did not have floating point hardware support.
// Floating point was done in software and floating point parameters were
// passed in integer registers. When hardware support was added for floating
// point, new *vfp functions were added to do the same operations but with
// floating point parameters in floating point registers.

// Undocumented functions

float __addsf3vfp(float a, float b); // Appears to return a + b
double __adddf3vfp(double a, double b); // Appears to return a + b
float __divsf3vfp(float a, float b); // Appears to return a / b
double __divdf3vfp(double a, double b); // Appears to return a / b
int __eqsf2vfp(float a, float b); // Appears to return one
// iff a == b and neither is NaN.
int __eqdf2vfp(double a, double b); // Appears to return one
// iff a == b and neither is NaN.
double __extendsfdf2vfp(float a); // Appears to convert from
// float to double.
int __fixdfsivfp(double a); // Appears to convert from
// double to int.
int __fixsfsivfp(float a); // Appears to convert from
// float to int.
unsigned int __fixunssfsivfp(float a); // Appears to convert from
// float to unsigned int.
unsigned int __fixunsdfsivfp(double a); // Appears to convert from
// double to unsigned int.
double __floatsidfvfp(int a); // Appears to convert from
// int to double.
float __floatsisfvfp(int a); // Appears to convert from
// int to float.
double __floatunssidfvfp(unsigned int a); // Appears to convert from
// unisgned int to double.
float __floatunssisfvfp(unsigned int a); // Appears to convert from
// unisgned int to float.
int __gedf2vfp(double a, double b); // Appears to return __gedf2
// (a >= b)
int __gesf2vfp(float a, float b); // Appears to return __gesf2
// (a >= b)
int __gtdf2vfp(double a, double b); // Appears to return __gtdf2
// (a > b)
int __gtsf2vfp(float a, float b); // Appears to return __gtsf2
// (a > b)
int __ledf2vfp(double a, double b); // Appears to return __ledf2
// (a <= b)
int __lesf2vfp(float a, float b); // Appears to return __lesf2
// (a <= b)
int __ltdf2vfp(double a, double b); // Appears to return __ltdf2
// (a < b)
int __ltsf2vfp(float a, float b); // Appears to return __ltsf2
// (a < b)
double __muldf3vfp(double a, double b); // Appears to return a * b
float __mulsf3vfp(float a, float b); // Appears to return a * b
int __nedf2vfp(double a, double b); // Appears to return __nedf2
// (a != b)
double __negdf2vfp(double a); // Appears to return -a
float __negsf2vfp(float a); // Appears to return -a
float __negsf2vfp(float a); // Appears to return -a
double __subdf3vfp(double a, double b); // Appears to return a - b
float __subsf3vfp(float a, float b); // Appears to return a - b
float __truncdfsf2vfp(double a); // Appears to convert from
// double to float.
int __unorddf2vfp(double a, double b); // Appears to return __unorddf2
int __unordsf2vfp(float a, float b); // Appears to return __unordsf2


Preconditions are listed for each function at the definition when there are any.
Any preconditions reflect the specification at
http://gcc.gnu.org/onlinedocs/gccint/Libgcc.html#Libgcc.

Assumptions are listed in "int_lib.h", and in individual files. Where possible
assumptions are checked at compile time.