1c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon//===-- comparesf2.S - Implement single-precision soft-float comparisons --===// 2c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 3c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// The LLVM Compiler Infrastructure 4c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 59ad441ffec97db647fee3725b3424284fb913e14Howard Hinnant// This file is dual licensed under the MIT and the University of Illinois Open 69ad441ffec97db647fee3725b3424284fb913e14Howard Hinnant// Source Licenses. See LICENSE.TXT for details. 7c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 8c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon//===----------------------------------------------------------------------===// 9c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 10c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// This file implements the following soft-fp_t comparison routines: 11c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 12c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// __eqsf2 __gesf2 __unordsf2 13c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// __lesf2 __gtsf2 14c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// __ltsf2 15c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// __nesf2 16c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 17c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// The semantics of the routines grouped in each column are identical, so there 18c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// is a single implementation for each, with multiple names. 19c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 20c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// The routines behave as follows: 21c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 22c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// __lesf2(a,b) returns -1 if a < b 23c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 0 if a == b 24c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 1 if a > b 25c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 1 if either a or b is NaN 26c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 27c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// __gesf2(a,b) returns -1 if a < b 28c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 0 if a == b 29c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 1 if a > b 30c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// -1 if either a or b is NaN 31c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 32c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// __unordsf2(a,b) returns 0 if both a and b are numbers 33c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 1 if either a or b is NaN 34c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 35c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// Note that __lesf2( ) and __gesf2( ) are identical except in their handling of 36c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// NaN values. 37c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon// 38c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon//===----------------------------------------------------------------------===// 39c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 40c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon#include "../assembly.h" 41c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon.syntax unified 42c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 43c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon.align 2 44c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen CanonDEFINE_COMPILERRT_FUNCTION(__eqsf2) 45c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen CanonDEFINE_COMPILERRT_FUNCTION(__lesf2) 46c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen CanonDEFINE_COMPILERRT_FUNCTION(__ltsf2) 47c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen CanonDEFINE_COMPILERRT_FUNCTION(__nesf2) 48c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // Make copies of a and b with the sign bit shifted off the top. These will 49c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // be used to detect zeros and NaNs. 50c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon mov r2, r0, lsl #1 51c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon mov r3, r1, lsl #1 52c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 53c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // We do the comparison in three stages (ignoring NaN values for the time 54c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // being). First, we orr the absolute values of a and b; this sets the Z 55c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // flag if both a and b are zero (of either sign). The shift of r3 doesn't 56c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // effect this at all, but it *does* make sure that the C flag is clear for 57c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // the subsequent operations. 58c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon orrs r12, r2, r3, lsr #1 59c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 60c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // Next, we check if a and b have the same or different signs. If they have 61c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // opposite signs, this eor will set the N flag. 62c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon eorsne r12, r0, r1 63c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 64c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // If a and b are equal (either both zeros or bit identical; again, we're 65c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // ignoring NaNs for now), this subtract will zero out r0. If they have the 66c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // same sign, the flags are updated as they would be for a comparison of the 67c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // absolute values of a and b. 68c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon subspl r0, r2, r3 69c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 70c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // If a is smaller in magnitude than b and both have the same sign, place 71c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // the negation of the sign of b in r0. Thus, if both are negative and 72c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // a > b, this sets r0 to 0; if both are positive and a < b, this sets 73c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // r0 to -1. 74c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // 75c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // This is also done if a and b have opposite signs and are not both zero, 76c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // because in that case the subtract was not performed and the C flag is 77c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // still clear from the shift argument in orrs; if a is positive and b 78c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // negative, this places 0 in r0; if a is negative and b positive, -1 is 79c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // placed in r0. 80c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon mvnlo r0, r1, asr #31 81c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 82c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // If a is greater in magnitude than b and both have the same sign, place 83c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // the sign of b in r0. Thus, if both are negative and a < b, -1 is placed 84c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // in r0, which is the desired result. Conversely, if both are positive 85c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // and a > b, zero is placed in r0. 86c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon movhi r0, r1, asr #31 87c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 88c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // If you've been keeping track, at this point r0 contains -1 if a < b and 89c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // 0 if a >= b. All that remains to be done is to set it to 1 if a > b. 90c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // If a == b, then the Z flag is set, so we can get the correct final value 91c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // into r0 by simply or'ing with 1 if Z is clear. 92c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon orrne r0, r0, #1 93c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 94c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // Finally, we need to deal with NaNs. If either argument is NaN, replace 95c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // the value in r0 with 1. 96c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon cmp r2, #0xff000000 97c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon cmpls r3, #0xff000000 98c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon movhi r0, #1 99c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon bx lr 100c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 101c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon.align 2 102c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen CanonDEFINE_COMPILERRT_FUNCTION(__gesf2) 103c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen CanonDEFINE_COMPILERRT_FUNCTION(__gtsf2) 104c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // Identical to the preceeding except in that we return -1 for NaN values. 105c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // Given that the two paths share so much code, one might be tempted to 106c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // unify them; however, the extra code needed to do so makes the code size 107c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // to performance tradeoff very hard to justify for such small functions. 108c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon mov r2, r0, lsl #1 109c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon mov r3, r1, lsl #1 110c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon orrs r12, r2, r3, lsr #1 111c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon eorsne r12, r0, r1 112c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon subspl r0, r2, r3 113c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon mvnlo r0, r1, asr #31 114c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon movhi r0, r1, asr #31 115c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon orrne r0, r0, #1 116c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon cmp r2, #0xff000000 117c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon cmpls r3, #0xff000000 118c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon movhi r0, #-1 119c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon bx lr 120c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon 121c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon.align 2 122c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen CanonDEFINE_COMPILERRT_FUNCTION(__unordsf2) 123c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon // Return 1 for NaN values, 0 otherwise. 124c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon mov r2, r0, lsl #1 125c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon mov r3, r1, lsl #1 126c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon mov r0, #0 127c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon cmp r2, #0xff000000 128c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon cmpls r3, #0xff000000 129c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon movhi r0, #1 130c8c6359f296d4f9e03b378b16ae34fb301e6b155Stephen Canon bx lr 131