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// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Push all callee-saved registers to get them on the stack for conservative
// stack scanning.
//
// See asm/x64/push_registers_clang.cc for why the function is not generated
// using clang.
// Do not depend on V8_TARGET_OS_* defines as some embedders may override the
// GN toolchain (e.g. ChromeOS) and not provide them.
// PPC ABI source:
// http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.html
// AIX Runtime process stack:
// https://www.ibm.com/support/knowledgecenter/ssw_aix_71/assembler/idalangref_runtime_process.html
asm(
#if defined(_AIX)
".globl .PushAllRegistersAndIterateStack, hidden \n"
".csect .text[PR] \n"
".PushAllRegistersAndIterateStack: \n"
#else
".globl PushAllRegistersAndIterateStack \n"
".type PushAllRegistersAndIterateStack, %function \n"
".hidden PushAllRegistersAndIterateStack \n"
"PushAllRegistersAndIterateStack: \n"
#endif
// Push all callee-saved registers.
// lr, TOC pointer, r16 to r31. 160 bytes.
// The parameter save area shall be allocated by the caller. 112 btes.
// At anytime, SP (r1) needs to be multiple of 16 (i.e. 16-aligned).
" mflr 0 \n"
" std 0, 16(1) \n"
#if defined(_AIX)
" std 2, 40(1) \n"
#else
" std 2, 24(1) \n"
#endif
" stdu 1, -256(1) \n"
" std 14, 112(1) \n"
" std 15, 120(1) \n"
" std 16, 128(1) \n"
" std 17, 136(1) \n"
" std 18, 144(1) \n"
" std 19, 152(1) \n"
" std 20, 160(1) \n"
" std 21, 168(1) \n"
" std 22, 176(1) \n"
" std 23, 184(1) \n"
" std 24, 192(1) \n"
" std 25, 200(1) \n"
" std 26, 208(1) \n"
" std 27, 216(1) \n"
" std 28, 224(1) \n"
" std 29, 232(1) \n"
" std 30, 240(1) \n"
" std 31, 248(1) \n"
// Pass 1st parameter (r3) unchanged (Stack*).
// Pass 2nd parameter (r4) unchanged (StackVisitor*).
// Save 3rd parameter (r5; IterateStackCallback).
" mr 6, 5 \n"
#if defined(_AIX)
// Set up TOC for callee.
" ld 2,8(5) \n"
// AIX uses function decorators, which means that
// pointers to functions do not point to code, but
// instead point to metadata about them, hence
// need to deterrence.
" ld 6,0(6) \n"
#endif
// Pass 3rd parameter as sp (stack pointer).
" mr 5, 1 \n"
#if !defined(_AIX)
// Set up r12 to be equal to the callee address (in order for TOC
// relocation). Only needed on LE Linux.
" mr 12, 6 \n"
#endif
// Call the callback.
" mtctr 6 \n"
" bctrl \n"
// Discard all the registers.
" addi 1, 1, 256 \n"
// Restore lr.
" ld 0, 16(1) \n"
" mtlr 0 \n"
#if defined(_AIX)
// Restore TOC pointer.
" ld 2, 40(1) \n"
#else
" ld 2, 24(1) \n"
#endif
" blr \n");
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