//===-- comparesf2.S - Implement single-precision soft-float comparisons --===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the following soft-fp_t comparison routines:
//
// __eqsf2 __gesf2 __unordsf2
// __lesf2 __gtsf2
// __ltsf2
// __nesf2
//
// The semantics of the routines grouped in each column are identical, so there
// is a single implementation for each, with multiple names.
//
// The routines behave as follows:
//
// __lesf2(a,b) returns -1 if a < b
// 0 if a == b
// 1 if a > b
// 1 if either a or b is NaN
//
// __gesf2(a,b) returns -1 if a < b
// 0 if a == b
// 1 if a > b
// -1 if either a or b is NaN
//
// __unordsf2(a,b) returns 0 if both a and b are numbers
// 1 if either a or b is NaN
//
// Note that __lesf2( ) and __gesf2( ) are identical except in their handling of
// NaN values.
//
//===----------------------------------------------------------------------===//
#include "../assembly.h"
.syntax unified
.text
DEFINE_CODE_STATE
.macro COMPARESF2_FUNCTION_BODY handle_nan:req
#if defined(COMPILER_RT_ARMHF_TARGET)
vmov r0, s0
vmov r1, s1
#endif
// Make copies of a and b with the sign bit shifted off the top. These will
// be used to detect zeros and NaNs.
#if defined(USE_THUMB_1)
push {r6, lr}
lsls r2, r0, #1
lsls r3, r1, #1
#else
mov r2, r0, lsl #1
mov r3, r1, lsl #1
#endif
// We do the comparison in three stages (ignoring NaN values for the time
// being). First, we orr the absolute values of a and b; this sets the Z
// flag if both a and b are zero (of either sign). The shift of r3 doesn't
// effect this at all, but it *does* make sure that the C flag is clear for
// the subsequent operations.
#if defined(USE_THUMB_1)
lsrs r6, r3, #1
orrs r6, r2
#else
orrs r12, r2, r3, lsr #1
#endif
// Next, we check if a and b have the same or different signs. If they have
// opposite signs, this eor will set the N flag.
#if defined(USE_THUMB_1)
beq 1f
movs r6, r0
eors r6, r1
1:
#else
it ne
eorsne r12, r0, r1
#endif
// If a and b are equal (either both zeros or bit identical; again, we're
// ignoring NaNs for now), this subtract will zero out r0. If they have the
// same sign, the flags are updated as they would be for a comparison of the
// absolute values of a and b.
#if defined(USE_THUMB_1)
bmi 1f
subs r0, r2, r3
1:
#else
it pl
subspl r0, r2, r3
#endif
// If a is smaller in magnitude than b and both have the same sign, place
// the negation of the sign of b in r0. Thus, if both are negative and
// a > b, this sets r0 to 0; if both are positive and a < b, this sets
// r0 to -1.
//
// This is also done if a and b have opposite signs and are not both zero,
// because in that case the subtract was not performed and the C flag is
// still clear from the shift argument in orrs; if a is positive and b
// negative, this places 0 in r0; if a is negative and b positive, -1 is
// placed in r0.
#if defined(USE_THUMB_1)
bhs 1f
// Here if a and b have the same sign and absA < absB, the result is thus
// b < 0 ? 1 : -1. Same if a and b have the opposite sign (ignoring Nan).
movs r0, #1
lsrs r1, #31
bne LOCAL_LABEL(CHECK_NAN\@)
negs r0, r0
b LOCAL_LABEL(CHECK_NAN\@)
1:
#else
it lo
mvnlo r0, r1, asr #31
#endif
// If a is greater in magnitude than b and both have the same sign, place
// the sign of b in r0. Thus, if both are negative and a < b, -1 is placed
// in r0, which is the desired result. Conversely, if both are positive
// and a > b, zero is placed in r0.
#if defined(USE_THUMB_1)
bls 1f
// Here both have the same sign and absA > absB.
movs r0, #1
lsrs r1, #31
beq LOCAL_LABEL(CHECK_NAN\@)
negs r0, r0
1:
#else
it hi
movhi r0, r1, asr #31
#endif
// If you've been keeping track, at this point r0 contains -1 if a < b and
// 0 if a >= b. All that remains to be done is to set it to 1 if a > b.
// If a == b, then the Z flag is set, so we can get the correct final value
// into r0 by simply or'ing with 1 if Z is clear.
// For Thumb-1, r0 contains -1 if a < b, 0 if a > b and 0 if a == b.
#if !defined(USE_THUMB_1)
it ne
orrne r0, r0, #1
#endif
// Finally, we need to deal with NaNs. If either argument is NaN, replace
// the value in r0 with 1.
#if defined(USE_THUMB_1)
LOCAL_LABEL(CHECK_NAN\@):
movs r6, #0xff
lsls r6, #24
cmp r2, r6
bhi 1f
cmp r3, r6
1:
bls 2f
\handle_nan
2:
pop {r6, pc}
#else
cmp r2, #0xff000000
ite ls
cmpls r3, #0xff000000
\handle_nan
JMP(lr)
#endif
.endm
@ int __eqsf2(float a, float b)
.p2align 2
DEFINE_COMPILERRT_FUNCTION(__eqsf2)
.macro __eqsf2_handle_nan
#if defined(USE_THUMB_1)
movs r0, #1
#else
movhi r0, #1
#endif
.endm
COMPARESF2_FUNCTION_BODY __eqsf2_handle_nan
END_COMPILERRT_FUNCTION(__eqsf2)
DEFINE_COMPILERRT_FUNCTION_ALIAS(__lesf2, __eqsf2)
DEFINE_COMPILERRT_FUNCTION_ALIAS(__ltsf2, __eqsf2)
DEFINE_COMPILERRT_FUNCTION_ALIAS(__nesf2, __eqsf2)
#if defined(__ELF__)
// Alias for libgcc compatibility
DEFINE_COMPILERRT_FUNCTION_ALIAS(cmpsf2, ____lesf2)
#endif
@ int __gtsf2(float a, float b)
.p2align 2
DEFINE_COMPILERRT_FUNCTION(__gtsf2)
.macro __gtsf2_handle_nan
#if defined(USE_THUMB_1)
movs r0, #1
negs r0, r0
#else
movhi r0, #-1
#endif
.endm
COMPARESF2_FUNCTION_BODY __gtsf2_handle_nan
END_COMPILERRT_FUNCTION(__gtsf2)
DEFINE_COMPILERRT_FUNCTION_ALIAS(__gesf2, __gtsf2)
@ int __unordsf2(float a, float b)
.p2align 2
DEFINE_COMPILERRT_FUNCTION(__unordsf2)
#if defined(COMPILER_RT_ARMHF_TARGET)
vmov r0, s0
vmov r1, s1
#endif
// Return 1 for NaN values, 0 otherwise.
lsls r2, r0, #1
lsls r3, r1, #1
movs r0, #0
#if defined(USE_THUMB_1)
movs r1, #0xff
lsls r1, #24
cmp r2, r1
bhi 1f
cmp r3, r1
1:
bls 2f
movs r0, #1
2:
#else
cmp r2, #0xff000000
ite ls
cmpls r3, #0xff000000
movhi r0, #1
#endif
JMP(lr)
END_COMPILERRT_FUNCTION(__unordsf2)
#if defined(COMPILER_RT_ARMHF_TARGET)
DEFINE_COMPILERRT_FUNCTION(__aeabi_fcmpun)
vmov s0, r0
vmov s1, r1
b SYMBOL_NAME(__unordsf2)
END_COMPILERRT_FUNCTION(__aeabi_fcmpun)
#else
DEFINE_AEABI_FUNCTION_ALIAS(__aeabi_fcmpun, __unordsf2)
#endif
NO_EXEC_STACK_DIRECTIVE