19ad441ffec97db647fee3725b3424284fb913e14Howard Hinnant// This file is dual licensed under the MIT and the University of Illinois Open 29ad441ffec97db647fee3725b3424284fb913e14Howard Hinnant// Source Licenses. See LICENSE.TXT for details. 3b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 419336a2d6b9b375ac106125950f4ff09742d1aecDaniel Dunbar#include "../assembly.h" 519336a2d6b9b375ac106125950f4ff09742d1aecDaniel Dunbar 6b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar// float __floatundisf(du_int a); 7b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 8b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar// Note that there is a hardware instruction, fildll, that does most of what 9b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar// this function needs to do. However, because of our ia32 ABI, it will take 10b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar// a write-small read-large stall, so the software implementation here is 11b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar// actually several cycles faster. 12b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 13b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar// This is a branch-free implementation. A branchy implementation might be 14b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar// faster for the common case if you know something a priori about the input 15b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar// distribution. 16b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 17b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar/* branch-free x87 implementation - one cycle slower than without x87. 18b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 19b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar#ifdef __i386__ 20b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 2186277eb844c4983c81de62d7c050e92fe7155788Stephen HinesCONST_SECTION 222d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines.balign 3 23b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 24b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar .quad 0x43f0000000000000 25b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbartwop64: .quad 0x0000000000000000 26b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 27b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar#define TWOp64 twop64-0b(%ecx,%eax,8) 28b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 29b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar.text 302d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines.balign 4 31b4b1e8c5085cf83a50242057775a33ae4323d402Daniel DunbarDEFINE_COMPILERRT_FUNCTION(__floatundisf) 32b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movl 8(%esp), %eax 33b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movd 8(%esp), %xmm1 34b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movd 4(%esp), %xmm0 35b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar punpckldq %xmm1, %xmm0 36b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar calll 0f 37b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar0: popl %ecx 38b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar sarl $31, %eax 39b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movq %xmm0, 4(%esp) 40b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar fildll 4(%esp) 41b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar faddl TWOp64 42b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar fstps 4(%esp) 43b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar flds 4(%esp) 44b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar ret 452d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen HinesEND_COMPILERRT_FUNCTION(__floatundisf) 462d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 47b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar#endif // __i386__ 48b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 49b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar*/ 50b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 51b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar/* branch-free, x87-free implementation - faster at the expense of code size */ 52b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 53b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar#ifdef __i386__ 54b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 5586277eb844c4983c81de62d7c050e92fe7155788Stephen HinesCONST_SECTION 566d1862363c88c183b0ed7740fca876342cf0474bStephen Hines 576d1862363c88c183b0ed7740fca876342cf0474bStephen Hines .balign 16 586d1862363c88c183b0ed7740fca876342cf0474bStephen Hinestwop52: 596d1862363c88c183b0ed7740fca876342cf0474bStephen Hines .quad 0x4330000000000000 606d1862363c88c183b0ed7740fca876342cf0474bStephen Hines .quad 0x0000000000000fff 616d1862363c88c183b0ed7740fca876342cf0474bStephen Hines 626d1862363c88c183b0ed7740fca876342cf0474bStephen Hines .balign 16 636d1862363c88c183b0ed7740fca876342cf0474bStephen Hinessticky: 646d1862363c88c183b0ed7740fca876342cf0474bStephen Hines .quad 0x0000000000000000 656d1862363c88c183b0ed7740fca876342cf0474bStephen Hines .long 0x00000012 666d1862363c88c183b0ed7740fca876342cf0474bStephen Hines 676d1862363c88c183b0ed7740fca876342cf0474bStephen Hines .balign 16 686d1862363c88c183b0ed7740fca876342cf0474bStephen Hinestwelve: 696d1862363c88c183b0ed7740fca876342cf0474bStephen Hines .long 0x00000000 70b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 71b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar#define TWOp52 twop52-0b(%ecx) 72b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar#define STICKY sticky-0b(%ecx,%eax,8) 73b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 74b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar.text 752d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines.balign 4 76b4b1e8c5085cf83a50242057775a33ae4323d402Daniel DunbarDEFINE_COMPILERRT_FUNCTION(__floatundisf) 77b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movl 8(%esp), %eax 78b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movd 8(%esp), %xmm1 79b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movd 4(%esp), %xmm0 80b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar punpckldq %xmm1, %xmm0 81b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 82b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar calll 0f 83b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar0: popl %ecx 84b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar shrl %eax // high 31 bits of input as sint32 85b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar addl $0x7ff80000, %eax 86b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar sarl $31, %eax // (big input) ? -1 : 0 87b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movsd STICKY, %xmm1 // (big input) ? 0xfff : 0 88b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movl $12, %edx 89b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar andl %eax, %edx // (big input) ? 12 : 0 90b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movd %edx, %xmm3 91b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar andpd %xmm0, %xmm1 // (big input) ? input & 0xfff : 0 92b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movsd TWOp52, %xmm2 // 0x1.0p52 93b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar psrlq %xmm3, %xmm0 // (big input) ? input >> 12 : input 94b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar orpd %xmm2, %xmm1 // 0x1.0p52 + ((big input) ? input & 0xfff : input) 95b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar orpd %xmm1, %xmm0 // 0x1.0p52 + ((big input) ? (input >> 12 | input & 0xfff) : input) 96b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar subsd %xmm2, %xmm0 // (double)((big input) ? (input >> 12 | input & 0xfff) : input) 97b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar cvtsd2ss %xmm0, %xmm0 // (float)((big input) ? (input >> 12 | input & 0xfff) : input) 98b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar pslld $23, %xmm3 99b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar paddd %xmm3, %xmm0 // (float)input 100b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar movd %xmm0, 4(%esp) 101b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar flds 4(%esp) 102b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar ret 1032d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen HinesEND_COMPILERRT_FUNCTION(__floatundisf) 1042d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 105b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar#endif // __i386__ 106c58a43648cd6121c51a2e795a28e2ef90d7813e6Pirama Arumuga Nainar 107c58a43648cd6121c51a2e795a28e2ef90d7813e6Pirama Arumuga NainarNO_EXEC_STACK_DIRECTIVE 108c58a43648cd6121c51a2e795a28e2ef90d7813e6Pirama Arumuga Nainar 109