libbcc
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+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
+tu_int __udivmodti4(tu_int a, tu_int b, tu_int* rem); // a / b, *rem = a % b
+
+// 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 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 instuction 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 <assert.h>
+void __eprintf(const char* format, const char* assertion_expression,
+ const char* line, const char* file);
+
+
+
+// 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.