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https://github.com/jart/cosmopolitan.git
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f4f4caab0e
I wanted a tiny scriptable meltdown proof way to run userspace programs and visualize how program execution impacts memory. It helps to explain how things like Actually Portable Executable works. It can show you how the GCC generated code is going about manipulating matrices and more. I didn't feel fully comfortable with Qemu and Bochs because I'm not smart enough to understand them. I wanted something like gVisor but with much stronger levels of assurances. I wanted a single binary that'll run, on all major operating systems with an embedded GPL barrier ZIP filesystem that is tiny enough to transpile to JavaScript and run in browsers too. https://justine.storage.googleapis.com/emulator625.mp4
208 lines
6.1 KiB
C++
208 lines
6.1 KiB
C++
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│vi: set et ft=asm ts=8 sw=8 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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/* clang-format off */
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#include "ape/relocations.h"
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#if __MNO_VZEROUPPER__ + 0
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#define vzeroupper
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#endif
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/ Begins definition of frameless function that calls no functions.
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.macro .leafprologue
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#if !(defined(TINY) && !defined(__PG__))
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push %rbp
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mov %rsp,%rbp
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#endif
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.endm
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/ Ends definition of frameless function that calls no functions.
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.macro .leafepilogue
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#if !(defined(TINY) && !defined(__PG__))
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pop %rbp
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#endif
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ret
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.endm
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/ Good alignment for functions where alignment actually helps.
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/ @note 16-byte
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.macro .alignfunc
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#ifndef __OPTIMIZE_SIZE__
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.p2align 4
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#endif
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.endm
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/ Good alignment for loops where alignment actually helps.
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/ @note 16-byte if <10 padding otherwise 8-byte
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.macro .alignloop
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#ifndef __OPTIMIZE_SIZE__
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.p2align 4,,10
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.p2align 4
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#endif
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.endm
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/ Loads Effective Address
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/ Supporting security blankets
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.macro plea symbol:req reg64:req reg32:req
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#if __PIC__ + __PIE__ + __code_model_medium__ + __code_model_large__ + 0 > 1
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lea \symbol(%rip),\reg64
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#else
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mov $\symbol,\reg32
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#endif
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.endm
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/ Loads Effective Address to Stack
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/ Supporting security blankets
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.macro pshaddr symbol:req
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#if __PIC__ + __PIE__ + __code_model_medium__ + __code_model_large__ + 0 > 1
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push $IMAGE_BASE_VIRTUAL+RVA(\symbol)(%rip),\reg64
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#else
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push $\symbol
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#endif
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.endm
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/ TODO(jart): delete
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/ Loads Effective Address
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/ Supporting security blankets
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.macro ezlea symbol:req reg:req
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#if __pic__ + __pie__ + __code_model_medium__ + __code_model_large__ + 0 > 1
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/ lea \symbol(%rip),%r\reg
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mov $\symbol,%e\reg
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#else
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mov $\symbol,%e\reg
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#endif
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.endm
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.macro farcall symbol:req
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.type \symbol,@function
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#if __PIC__ + __PIE__ + __code_model_medium__ + __code_model_large__ + 0 > 1
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call *\symbol\()@gotpcrel(%rip)
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#else
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call \symbol\()@plt
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#endif
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.endm
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/ Creates first stack frame.
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.macro .frame0
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and $-16,%rsp
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xor %ebp,%ebp
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.endm
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/ Pulls source code file into ZIP portion of binary.
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/
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/ @param symbol is quoted path relative to root e.g. __FILE__
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/ @see see libc/zipos/zipcentraldir.S
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/ @see see libc/integral/c.inc
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.macro .source symbol:req
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#ifndef IM_FEELING_NAUGHTY
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.yoink "\symbol"
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#endif
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.endm
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/ Inserts profiling hook in prologue if cc wants it.
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/
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/ Cosmopolitan does this in a slightly different way from normal
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/ GNU toolchains. We always use the -mnop-mcount behavior, since
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/ the runtime is able to morph the binary at runtime. It is good
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/ since we can put hooks for profiling and function tracing into
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/ most builds, without any impact on performance.
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/
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/ @cost ≥0.3 cycles, 5 bytes
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/ @see build/compile
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.macro .profilable
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#ifdef __PG__
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1382:
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#if defined(__MFENTRY__)
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call __fentry__
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#elif defined(__PIC__) || defined(__PIE__)
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/ nopw 0x00(%rax,%rax,1)
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.byte 0x66,0x0f,0x1f,0x44,0x00,0x00
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#else
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/ nopl 0x00(%rax,%rax,1)
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.byte 0x0f,0x1f,0x44,0x00,0x00
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#endif
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#if defined(__MRECORD_MCOUNT__) && !defined(__MFENTRY__)
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.pushsection __mcount_loc,"a",@progbits
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.quad 1382b
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.popsection
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#endif
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#endif
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.endm
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/ Pushes RVA on stack of linktime mergeable string literal.
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/ @see popstr
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.macro pushstr text
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.pushsection .rodata.str1.1,"aSM",@progbits,1
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.Lstr\@: .asciz "\text"
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.endobj .Lstr\@
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.popsection
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push $.Lstr\@ - IMAGE_BASE_VIRTUAL
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.endm
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/ Pops off stack string address.
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/ @see pushstr
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.macro popstr dest:req
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addl $IMAGE_BASE_VIRTUAL,(%rsp)
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pop \dest
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.endm
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/ Loads address of linktime mergeable string literal into register.
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.macro getstr text:req reg64:req reg32 regsz64 regsz32 bias=0
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.pushsection .rodata.str1.1,"aSM",@progbits,1
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.type .Lstr\@,@object
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.Lstr\@: .asciz "\text"
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.Lstr\@.size = .-.Lstr\@ - 1
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.size .Lstr\@,.-.Lstr\@
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.popsection
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plea .Lstr\@,\reg64,\reg32
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.ifnb \regsz64
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#ifdef __OPTIMIZE_SIZE__
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.if .Lstr\@.size + \bias < 128
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pushpop .Lstr\@.size,\regsz64
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.else
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mov $.Lstr\@.size,\regsz32
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.endif
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#else
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mov $.Lstr\@.size,\regsz32
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#endif
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.endif
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.endm
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/ TODO(jart): delete
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/ Loads address of linktime mergeable string literal into register.
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.macro loadstr text:req reg:req regsz bias=0
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.pushsection .rodata.str1.1,"aSM",@progbits,1
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.type .Lstr\@,@object
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.Lstr\@: .asciz "\text"
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.Lstr\@.size = .-.Lstr\@ - 1
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.size .Lstr\@,.-.Lstr\@
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.popsection
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ezlea .Lstr\@,\reg
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.ifnb \regsz
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#ifdef __OPTIMIZE_SIZE__
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.if .Lstr\@.size + \bias < 128
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pushpop .Lstr\@.size,%r\regsz
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.else
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mov $.Lstr\@.size,%e\regsz
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.endif
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#else
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mov $.Lstr\@.size,%e\regsz
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#endif
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.endif
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.endm
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