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Cider Isn't Darwin Emulation, Really
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105/* double floor( double ) * * Reimplemented by Steve Canon, based on Ian Ollmann's implementations * tuned for increased performance on in-order machines (but faster on * out-of-order machines as well). * * Copyright 2009, Apple Inc. */
#ifdef __i386__
#ifdef __SSE3__
.text.align 4.globl _floor_floor: mov 8(%esp), %ecx fldl 4(%esp) cmp $0x43300000, %ecx // if x is negative or x > 0x1.0p53 jae 1f // goto 1 fisttpll 4(%esp) // fast path if +0 <= x < 0x1.0p52 fildll 4(%esp) // return trunc(x) ret 1: and $0x7fffffff, %ecx sub $1, %ecx cmp $0x43300000, %ecx // if |x| > 0x1.0p52 or isnan(x) or fld %st(0) // the high word of |x| is zero, jae 4f // goto 4 2: fistpll 4(%esp) fildll 4(%esp) // rint(x) fucomi %st(1), %st(0) fstp %st(1) jbe 3f // if rint(x) <= x, return rint(x) fld1 fsubrp %st(0), %st(1) // otherwise, return rint(x) - 1.03: ret
4: jg 5f // if |x| > 0x1.0p52 or isnan(x), return x testl $0xffffffff, 4(%esp) // if x is -denorm, go back through the jnz 2b // main path, returning -1.05: fstp %st(1) // otherwise, pop the extra copy of x, and ret // return x. #else // i386, no SSE3
.text.align 4.globl _floor_floor: mov 8(%esp), %ecx and $0x7fffffff, %ecx // high word of |x| fldl 4(%esp) sub $1, %ecx cmp $0x432fffff, %ecx // if |x| >= 0x1.0p52 or isnan(x) or iszero(x) fld %st(0) // or x is a denormal whose high 32 bits are jae 2f // all zero, goto 2
0: fistpll 4(%esp) fildll 4(%esp) // rint(x) fucomi %st(1), %st(0) fstp %st(1) jbe 1f // if rint(x) <= x, return rint(x) fld1 fsubrp %st(0), %st(1) // otherwise, return rint(x) - 1.01: ret
2: jg 3f // if |x| >= 0x1.0p52 or isnan(x), goto 3 testl $0xffffffff, 4(%esp) // if x is denorm (not zero) jnz 0b // jump back to the mainline3: fstp %st(1) // pop the extra copy of x off the stack ret // and return x
#endif // SSE3 #else // x86_64
.const.align 4mone: .quad 0xbff0000000000000absmask:.quad 0x7fffffffffffffffthresh: .quad 0x432fffffffffffff
.text.align 4.globl _floor_floor: movd %xmm0, %rcx andq absmask(%rip), %rcx // |x| subq $1, %rcx cmpq thresh(%rip), %rcx // if |x| >= 0x1.0p52 or isnan(x) or iszero(x) jae 1f // early out, returning x.
cvttsd2si %xmm0, %rax cvtsi2sd %rax, %xmm1 // trunc(x) cmpltsd %xmm1, %xmm0 andpd mone(%rip), %xmm0 // x < trunc(x) ? -1.0 : 0.0 addsd %xmm1, %xmm0 // floor(x)1: ret
#endif