Initial import of compiler-rt.
-
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@74292 91177308-0d34-0410-b5e6-96231b3b80d8
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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 replacment 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
+di_int __ashrdi3(di_int a, si_int b); // a >> b arithmetic (sign fill)
+di_int __lshrdi3(di_int a, si_int b); // a >> b logical (zero fill)
+
+si_int __clzsi2(si_int a); // count leading zeroes
+si_int __clzdi2(di_int a); // count leading zeroes
+si_int __ctzsi2(si_int a); // count trailing zeroes
+si_int __ctzdi2(di_int a); // count trailing zeroes
+
+si_int __ffsdi2(di_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 __popcountsi2(si_int a); // bit population
+si_int __popcountdi2(di_int a); // bit population
+
+// Integral arithmetic
+
+di_int __negdi2 (di_int a); // -a
+di_int __muldi3 (di_int a, di_int b); // a * b
+di_int __divdi3 (di_int a, di_int b); // a / b signed
+du_int __udivdi3 (du_int a, du_int b); // a / b unsigned
+di_int __moddi3 (di_int a, di_int b); // a % b signed
+du_int __umoddi3 (du_int a, du_int b); // a % b unsigned
+du_int __udivmoddi4(du_int a, du_int b, du_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)
+
+si_int __negvsi2(si_int a); // -a
+di_int __negvdi2(di_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
+
+si_int __subvsi3(si_int a, si_int b); // a - b
+di_int __subvdi3(di_int a, di_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
+
+// Integral comparison: a < b -> 0
+// a == b -> 1
+// a > b -> 2
+
+si_int __cmpdi2 (di_int a, di_int b);
+si_int __ucmpdi2(du_int a, du_int b);
+
+// Integral / floating point conversion
+
+di_int __fixsfdi( float a);
+di_int __fixdfdi( double a);
+di_int __fixxfdi(long double a);
+
+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);
+
+float __floatdisf(di_int a);
+double __floatdidf(di_int a);
+long double __floatdixf(di_int a);
+
+float __floatundisf(du_int a);
+double __floatundidf(du_int a);
+long double __floatundixf(du_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
+
+// 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);
+
+// (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);
+
+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.