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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
commit | 43a123c1ae6613b3efeed291fa552ecd909d3acf (patch) | |
tree | fd92518b7024bc74031f78a1cf9e454b65e73665 /src/runtime/vlop_arm.s | |
parent | Initial commit. (diff) | |
download | golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.tar.xz golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.zip |
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/runtime/vlop_arm.s')
-rw-r--r-- | src/runtime/vlop_arm.s | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/src/runtime/vlop_arm.s b/src/runtime/vlop_arm.s new file mode 100644 index 0000000..9e19938 --- /dev/null +++ b/src/runtime/vlop_arm.s @@ -0,0 +1,260 @@ +// Inferno's libkern/vlop-arm.s +// https://bitbucket.org/inferno-os/inferno-os/src/master/libkern/vlop-arm.s +// +// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved. +// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved. +// Portions Copyright 2009 The Go Authors. All rights reserved. +// +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in +// all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +// THE SOFTWARE. + +#include "go_asm.h" +#include "go_tls.h" +#include "funcdata.h" +#include "textflag.h" + +// func runtime·udiv(n, d uint32) (q, r uint32) +// compiler knowns the register usage of this function +// Reference: +// Sloss, Andrew et. al; ARM System Developer's Guide: Designing and Optimizing System Software +// Morgan Kaufmann; 1 edition (April 8, 2004), ISBN 978-1558608740 +#define Rq R0 // input d, output q +#define Rr R1 // input n, output r +#define Rs R2 // three temporary variables +#define RM R3 +#define Ra R11 + +// Be careful: Ra == R11 will be used by the linker for synthesized instructions. +// Note: this function does not have a frame. +TEXT runtime·udiv(SB),NOSPLIT|NOFRAME,$0 + MOVBU internal∕cpu·ARM+const_offsetARMHasIDIVA(SB), Ra + CMP $0, Ra + BNE udiv_hardware + + CLZ Rq, Rs // find normalizing shift + MOVW.S Rq<<Rs, Ra + MOVW $fast_udiv_tab<>-64(SB), RM + ADD.NE Ra>>25, RM, Ra // index by most significant 7 bits of divisor + MOVBU.NE (Ra), Ra + + SUB.S $7, Rs + RSB $0, Rq, RM // M = -q + MOVW.PL Ra<<Rs, Rq + + // 1st Newton iteration + MUL.PL RM, Rq, Ra // a = -q*d + BMI udiv_by_large_d + MULAWT Ra, Rq, Rq, Rq // q approx q-(q*q*d>>32) + TEQ RM->1, RM // check for d=0 or d=1 + + // 2nd Newton iteration + MUL.NE RM, Rq, Ra + MOVW.NE $0, Rs + MULAL.NE Rq, Ra, (Rq,Rs) + BEQ udiv_by_0_or_1 + + // q now accurate enough for a remainder r, 0<=r<3*d + MULLU Rq, Rr, (Rq,Rs) // q = (r * q) >> 32 + ADD RM, Rr, Rr // r = n - d + MULA RM, Rq, Rr, Rr // r = n - (q+1)*d + + // since 0 <= n-q*d < 3*d; thus -d <= r < 2*d + CMN RM, Rr // t = r-d + SUB.CS RM, Rr, Rr // if (t<-d || t>=0) r=r+d + ADD.CC $1, Rq + ADD.PL RM<<1, Rr + ADD.PL $2, Rq + RET + +// use hardware divider +udiv_hardware: + DIVUHW Rq, Rr, Rs + MUL Rs, Rq, RM + RSB Rr, RM, Rr + MOVW Rs, Rq + RET + +udiv_by_large_d: + // at this point we know d>=2^(31-6)=2^25 + SUB $4, Ra, Ra + RSB $0, Rs, Rs + MOVW Ra>>Rs, Rq + MULLU Rq, Rr, (Rq,Rs) + MULA RM, Rq, Rr, Rr + + // q now accurate enough for a remainder r, 0<=r<4*d + CMN Rr>>1, RM // if(r/2 >= d) + ADD.CS RM<<1, Rr + ADD.CS $2, Rq + CMN Rr, RM + ADD.CS RM, Rr + ADD.CS $1, Rq + RET + +udiv_by_0_or_1: + // carry set if d==1, carry clear if d==0 + BCC udiv_by_0 + MOVW Rr, Rq + MOVW $0, Rr + RET + +udiv_by_0: + MOVW $runtime·panicdivide(SB), R11 + B (R11) + +// var tab [64]byte +// tab[0] = 255; for i := 1; i <= 63; i++ { tab[i] = (1<<14)/(64+i) } +// laid out here as little-endian uint32s +DATA fast_udiv_tab<>+0x00(SB)/4, $0xf4f8fcff +DATA fast_udiv_tab<>+0x04(SB)/4, $0xe6eaedf0 +DATA fast_udiv_tab<>+0x08(SB)/4, $0xdadde0e3 +DATA fast_udiv_tab<>+0x0c(SB)/4, $0xcfd2d4d7 +DATA fast_udiv_tab<>+0x10(SB)/4, $0xc5c7cacc +DATA fast_udiv_tab<>+0x14(SB)/4, $0xbcbec0c3 +DATA fast_udiv_tab<>+0x18(SB)/4, $0xb4b6b8ba +DATA fast_udiv_tab<>+0x1c(SB)/4, $0xacaeb0b2 +DATA fast_udiv_tab<>+0x20(SB)/4, $0xa5a7a8aa +DATA fast_udiv_tab<>+0x24(SB)/4, $0x9fa0a2a3 +DATA fast_udiv_tab<>+0x28(SB)/4, $0x999a9c9d +DATA fast_udiv_tab<>+0x2c(SB)/4, $0x93949697 +DATA fast_udiv_tab<>+0x30(SB)/4, $0x8e8f9092 +DATA fast_udiv_tab<>+0x34(SB)/4, $0x898a8c8d +DATA fast_udiv_tab<>+0x38(SB)/4, $0x85868788 +DATA fast_udiv_tab<>+0x3c(SB)/4, $0x81828384 +GLOBL fast_udiv_tab<>(SB), RODATA, $64 + +// The linker will pass numerator in R8 +#define Rn R8 +// The linker expects the result in RTMP +#define RTMP R11 + +TEXT runtime·_divu(SB), NOSPLIT, $16-0 + // It's not strictly true that there are no local pointers. + // It could be that the saved registers Rq, Rr, Rs, and Rm + // contain pointers. However, the only way this can matter + // is if the stack grows (which it can't, udiv is nosplit) + // or if a fault happens and more frames are added to + // the stack due to deferred functions. + // In the latter case, the stack can grow arbitrarily, + // and garbage collection can happen, and those + // operations care about pointers, but in that case + // the calling frame is dead, and so are the saved + // registers. So we can claim there are no pointers here. + NO_LOCAL_POINTERS + MOVW Rq, 4(R13) + MOVW Rr, 8(R13) + MOVW Rs, 12(R13) + MOVW RM, 16(R13) + + MOVW Rn, Rr /* numerator */ + MOVW g_m(g), Rq + MOVW m_divmod(Rq), Rq /* denominator */ + BL runtime·udiv(SB) + MOVW Rq, RTMP + MOVW 4(R13), Rq + MOVW 8(R13), Rr + MOVW 12(R13), Rs + MOVW 16(R13), RM + RET + +TEXT runtime·_modu(SB), NOSPLIT, $16-0 + NO_LOCAL_POINTERS + MOVW Rq, 4(R13) + MOVW Rr, 8(R13) + MOVW Rs, 12(R13) + MOVW RM, 16(R13) + + MOVW Rn, Rr /* numerator */ + MOVW g_m(g), Rq + MOVW m_divmod(Rq), Rq /* denominator */ + BL runtime·udiv(SB) + MOVW Rr, RTMP + MOVW 4(R13), Rq + MOVW 8(R13), Rr + MOVW 12(R13), Rs + MOVW 16(R13), RM + RET + +TEXT runtime·_div(SB),NOSPLIT,$16-0 + NO_LOCAL_POINTERS + MOVW Rq, 4(R13) + MOVW Rr, 8(R13) + MOVW Rs, 12(R13) + MOVW RM, 16(R13) + MOVW Rn, Rr /* numerator */ + MOVW g_m(g), Rq + MOVW m_divmod(Rq), Rq /* denominator */ + CMP $0, Rr + BGE d1 + RSB $0, Rr, Rr + CMP $0, Rq + BGE d2 + RSB $0, Rq, Rq +d0: + BL runtime·udiv(SB) /* none/both neg */ + MOVW Rq, RTMP + B out1 +d1: + CMP $0, Rq + BGE d0 + RSB $0, Rq, Rq +d2: + BL runtime·udiv(SB) /* one neg */ + RSB $0, Rq, RTMP +out1: + MOVW 4(R13), Rq + MOVW 8(R13), Rr + MOVW 12(R13), Rs + MOVW 16(R13), RM + RET + +TEXT runtime·_mod(SB),NOSPLIT,$16-0 + NO_LOCAL_POINTERS + MOVW Rq, 4(R13) + MOVW Rr, 8(R13) + MOVW Rs, 12(R13) + MOVW RM, 16(R13) + MOVW Rn, Rr /* numerator */ + MOVW g_m(g), Rq + MOVW m_divmod(Rq), Rq /* denominator */ + CMP $0, Rq + RSB.LT $0, Rq, Rq + CMP $0, Rr + BGE m1 + RSB $0, Rr, Rr + BL runtime·udiv(SB) /* neg numerator */ + RSB $0, Rr, RTMP + B out +m1: + BL runtime·udiv(SB) /* pos numerator */ + MOVW Rr, RTMP +out: + MOVW 4(R13), Rq + MOVW 8(R13), Rr + MOVW 12(R13), Rs + MOVW 16(R13), RM + RET + +// _mul64by32 and _div64by32 not implemented on arm +TEXT runtime·_mul64by32(SB), NOSPLIT, $0 + MOVW $0, R0 + MOVW (R0), R1 // crash + +TEXT runtime·_div64by32(SB), NOSPLIT, $0 + MOVW $0, R0 + MOVW (R0), R1 // crash |