| // 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. |
| |
| // We maintain 8-byte alignment at calls by pushing an additional |
| // non-callee-saved register (r3). |
| // |
| // Calling convention source: |
| // https://en.wikipedia.org/wiki/Calling_convention#ARM_(A32) |
| // http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka4127.html |
| asm(".globl PushAllRegistersAndIterateStack \n" |
| ".type PushAllRegistersAndIterateStack, %function \n" |
| ".hidden PushAllRegistersAndIterateStack \n" |
| "PushAllRegistersAndIterateStack: \n" |
| // Push all callee-saved registers and save return address. |
| // Only {r4-r11} are callee-saved registers. Push r3 in addition to align |
| // the stack back to 8 bytes. |
| " push {r3-r11, lr} \n" |
| // Pass 1st parameter (r0) unchanged (Stack*). |
| // Pass 2nd parameter (r1) unchanged (StackVisitor*). |
| // Save 3rd parameter (r2; IterateStackCallback). |
| " mov r3, r2 \n" |
| // Pass 3rd parameter as sp (stack pointer). |
| " mov r2, sp \n" |
| // Call the callback. |
| " blx r3 \n" |
| // Discard all the registers. |
| " add sp, sp, #36 \n" |
| // Pop lr into pc which returns and switches mode if needed. |
| " pop {pc} \n"); |
