487 lines
		
	
	
		
			17 KiB
		
	
	
	
		
			ArmAsm
		
	
	
	
			
		
		
	
	
			487 lines
		
	
	
		
			17 KiB
		
	
	
	
		
			ArmAsm
		
	
	
	
| /*
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|  * Copyright (C) 2013 The Android Open Source Project
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|  *
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|  * Licensed under the Apache License, Version 2.0 (the "License");
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|  * you may not use this file except in compliance with the License.
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|  * You may obtain a copy of the License at
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|  *
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|  *      http://www.apache.org/licenses/LICENSE-2.0
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|  *
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|  * Unless required by applicable law or agreed to in writing, software
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|  * distributed under the License is distributed on an "AS IS" BASIS,
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|  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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|  * See the License for the specific language governing permissions and
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|  * limitations under the License.
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|  */
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| 
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| #ifndef ART_RUNTIME_ARCH_X86_ASM_SUPPORT_X86_S_
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| #define ART_RUNTIME_ARCH_X86_ASM_SUPPORT_X86_S_
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| 
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| #include "asm_support_x86.h"
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| #include "interpreter/cfi_asm_support.h"
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| 
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| // Regular gas(1) & current clang/llvm assembler support named macro parameters.
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| #define MACRO0(macro_name) .macro macro_name
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| #define MACRO1(macro_name, macro_arg1) .macro macro_name macro_arg1
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| #define MACRO2(macro_name, macro_arg1, macro_arg2) .macro macro_name macro_arg1, macro_arg2
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| #define MACRO3(macro_name, macro_arg1, macro_arg2, macro_arg3) .macro macro_name macro_arg1, macro_arg2, macro_arg3
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| #define MACRO4(macro_name, macro_arg1, macro_arg2, macro_arg3, macro_arg4) .macro macro_name macro_arg1, macro_arg2, macro_arg3, macro_arg4
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| #define MACRO5(macro_name, macro_arg1, macro_arg2, macro_arg3, macro_arg4, macro_arg5) .macro macro_name macro_arg1, macro_arg2, macro_arg3, macro_arg4, macro_arg5
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| #define END_MACRO .endm
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| 
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| #if defined(__clang__)
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|     // Clang/llvm does not support .altmacro. However, the clang/llvm preprocessor doesn't
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|     // separate the backslash and parameter by a space. Everything just works.
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|     #define RAW_VAR(name) \name
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|     #define VAR(name) \name
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|     #define CALLVAR(name) SYMBOL(\name)
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|     #define PLT_VAR(name) \name@PLT
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|     #define REG_VAR(name) %\name
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|     #define CALL_MACRO(name) \name
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| #else
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|     // Regular gas(1) uses \argument_name for macro arguments.
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|     // We need to turn on alternate macro syntax so we can use & instead or the preprocessor
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|     // will screw us by inserting a space between the \ and the name. Even in this mode there's
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|     // no special meaning to $, so literals are still just $x. The use of altmacro means % is a
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|     // special character meaning care needs to be taken when passing registers as macro
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|     // arguments.
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|     .altmacro
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|     #define RAW_VAR(name) name&
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|     #define VAR(name) name&
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|     #define CALLVAR(name) SYMBOL(name&)
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|     #define PLT_VAR(name) name&@PLT
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|     #define REG_VAR(name) %name
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|     #define CALL_MACRO(name) name&
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| #endif
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| 
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| #define LITERAL(value) $value
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| #if defined(__APPLE__)
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|     #define MACRO_LITERAL(value) $(value)
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| #else
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|     #define MACRO_LITERAL(value) $value
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| #endif
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| 
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| #if defined(__APPLE__)
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|     #define FUNCTION_TYPE(name)
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|     #define SIZE(name)
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| #else
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|     #define FUNCTION_TYPE(name) .type name, @function
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|     #define SIZE(name) .size name, .-name
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| #endif
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| 
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|     // CFI support.
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| #if !defined(__APPLE__)
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|     #define CFI_STARTPROC .cfi_startproc
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|     #define CFI_ENDPROC .cfi_endproc
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|     #define CFI_ADJUST_CFA_OFFSET(size) .cfi_adjust_cfa_offset size
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|     #define CFI_DEF_CFA(reg,size) .cfi_def_cfa reg,size
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|     #define CFI_DEF_CFA_REGISTER(reg) .cfi_def_cfa_register reg
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|     #define CFI_RESTORE(reg) .cfi_restore reg
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|     #define CFI_REL_OFFSET(reg,size) .cfi_rel_offset reg,size
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|     #define CFI_REGISTER(orig_reg, current_reg) .cfi_register orig_reg, current_reg
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|     #define CFI_REMEMBER_STATE .cfi_remember_state
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|     // The spec is not clear whether the CFA is part of the saved state and tools
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|     // differ in the behaviour, so explicitly set the CFA to avoid any ambiguity.
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|     // The restored CFA state should match the CFA state during CFI_REMEMBER_STATE.
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|     // `objdump -Wf libart.so | egrep "_cfa|_state"` is useful to audit the opcodes.
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|     MACRO2(CFI_RESTORE_STATE_AND_DEF_CFA, reg, off)
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|         .cfi_restore_state
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|         .cfi_def_cfa \reg,\off
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|     END_MACRO
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|     #define CFI_ESCAPE(...) .cfi_escape __VA_ARGS__
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|     #define CFI_RESTORE_STATE .cfi_restore_state
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| #else
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|     // Mac OS' doesn't like cfi_* directives.
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|     #define CFI_STARTPROC
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|     #define CFI_ENDPROC
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|     #define CFI_ADJUST_CFA_OFFSET(size)
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|     #define CFI_DEF_CFA(reg,size)
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|     #define CFI_DEF_CFA_REGISTER(reg)
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|     #define CFI_RESTORE(reg)
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|     #define CFI_REL_OFFSET(reg,size)
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|     #define CFI_REGISTER(orig_reg, current_reg)
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|     #define CFI_REMEMBER_STATE
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|     MACRO2(CFI_RESTORE_STATE_AND_DEF_CFA, reg, off)
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|     END_MACRO
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|     #define CFI_ESCAPE(...)
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|     #define CFI_RESTORE_STATE
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| #endif
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| 
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| #define CFI_REG_eax 0
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| #define CFI_REG_ecx 1
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| #define CFI_REG_edx 2
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| #define CFI_REG_ebx 3
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| #define CFI_REG_esp 4
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| #define CFI_REG_ebp 5
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| #define CFI_REG_esi 6
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| #define CFI_REG_edi 7
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| #define CFI_REG_eip 8
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| 
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| #define CFI_REG(reg) CFI_REG_##reg
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| 
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| MACRO3(CFI_EXPRESSION_BREG, n, b, offset)
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|     .if (-0x40 <= (\offset)) && ((\offset) < 0x40)
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|         CFI_EXPRESSION_BREG_1(\n, \b, \offset)
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|     .elseif (-0x2000 <= (\offset)) && ((\offset) < 0x2000)
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|         CFI_EXPRESSION_BREG_2(\n, \b, \offset)
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|     .else
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|         .error "Unsupported offset"
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|     .endif
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| END_MACRO
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| 
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| MACRO3(CFI_DEF_CFA_BREG_PLUS_UCONST, reg, offset, size)
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|     .if ((\size) < 0)
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|         .error "Size should be positive"
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|     .endif
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|     .if (((\offset) < -0x40) || ((\offset) >= 0x40))
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|         .error "Unsupported offset"
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|     .endif
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|     .if ((\size) < 0x80)
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|         CFI_DEF_CFA_BREG_PLUS_UCONST_1_1(\reg, \offset, \size)
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|     .elseif ((\size) < 0x4000)
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|         CFI_DEF_CFA_BREG_PLUS_UCONST_1_2(\reg, \offset, \size)
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|     .else
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|         .error "Unsupported size"
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|     .endif
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| END_MACRO
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| 
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|     // Symbols. On a Mac, we need a leading underscore.
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| #if !defined(__APPLE__)
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|     #define SYMBOL(name) name
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|     #define PLT_SYMBOL(name) name ## @PLT
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| #else
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|     // Mac OS' symbols have an _ prefix.
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|     #define SYMBOL(name) _ ## name
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|     #define PLT_SYMBOL(name) _ ## name
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| #endif
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| 
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| // Directive to hide a function symbol.
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| #if defined(__APPLE__)
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|     #define ASM_HIDDEN .private_extern
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| #else
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|     #define ASM_HIDDEN .hidden
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| #endif
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| 
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|     /* Cache alignment for function entry */
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| MACRO0(ALIGN_FUNCTION_ENTRY)
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|     // ART-compiled functions have OatQuickMethodHeader but assembly funtions do not.
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|     // Prefix the assembly code with 0xFFs, which means there is no method header.
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|     .byte 0xFF, 0xFF, 0xFF, 0xFF
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|     // Cache alignment for function entry.
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|     .balign 16, 0xFF
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| END_MACRO
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| 
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| MACRO2(DEFINE_FUNCTION_CUSTOM_CFA, c_name, cfa_offset)
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|     FUNCTION_TYPE(SYMBOL(\c_name))
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|     ASM_HIDDEN CALLVAR(c_name)
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|     .globl CALLVAR(c_name)
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|     ALIGN_FUNCTION_ENTRY
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| CALLVAR(c_name):
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|     CFI_STARTPROC
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|     // Ensure we get an appropriate starting CFA.
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|     CFI_DEF_CFA(esp, RAW_VAR(cfa_offset))
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| END_MACRO
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| 
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| MACRO1(DEFINE_FUNCTION, c_name)
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|     DEFINE_FUNCTION_CUSTOM_CFA RAW_VAR(c_name), __SIZEOF_POINTER__
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| END_MACRO
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| 
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| MACRO1(END_FUNCTION, c_name)
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|     CFI_ENDPROC
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|     SIZE(SYMBOL(\c_name))
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| END_MACRO
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| 
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| MACRO1(PUSH, reg)
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|     pushl REG_VAR(reg)
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|     CFI_ADJUST_CFA_OFFSET(4)
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|     CFI_REL_OFFSET(REG_VAR(reg), 0)
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| END_MACRO
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| 
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| MACRO1(POP, reg)
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|     popl REG_VAR(reg)
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|     CFI_ADJUST_CFA_OFFSET(-4)
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|     CFI_RESTORE(REG_VAR(reg))
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| END_MACRO
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| 
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| // Arguments do not need .cfi_rel_offset as they are caller-saved and
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| // therefore cannot hold caller's variables or unwinding data.
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| MACRO1(PUSH_ARG, reg)
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|     pushl REG_VAR(reg)
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|     CFI_ADJUST_CFA_OFFSET(4)
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| END_MACRO
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| 
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| MACRO1(POP_ARG, reg)
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|     popl REG_VAR(reg)
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|     CFI_ADJUST_CFA_OFFSET(-4)
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| END_MACRO
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| 
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| MACRO1(CFI_RESTORE_REG, reg)
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|     CFI_RESTORE(REG_VAR(reg))
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| END_MACRO
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| 
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| MACRO1(INCREASE_FRAME, frame_adjustment)
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|     subl MACRO_LITERAL(RAW_VAR(frame_adjustment)), %esp
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|     CFI_ADJUST_CFA_OFFSET((RAW_VAR(frame_adjustment)))
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| END_MACRO
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| 
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| MACRO1(DECREASE_FRAME, frame_adjustment)
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|     addl MACRO_LITERAL(RAW_VAR(frame_adjustment)), %esp
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|     CFI_ADJUST_CFA_OFFSET(-(RAW_VAR(frame_adjustment)))
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| END_MACRO
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| 
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| #define UNREACHABLE int3
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| 
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| MACRO1(UNIMPLEMENTED,name)
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|     FUNCTION_TYPE(\name)
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|     .globl VAR(name)
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|     ALIGN_FUNCTION_ENTRY
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| VAR(name):
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|     CFI_STARTPROC
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|     UNREACHABLE
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|     UNREACHABLE
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|     CFI_ENDPROC
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|     SIZE(\name)
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| END_MACRO
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| 
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| MACRO3(SETUP_PC_REL_BASE_IMPL, reg, label, call_label)
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|     call RAW_VAR(call_label)
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|     CFI_ADJUST_CFA_OFFSET(4)
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| RAW_VAR(label):
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|     popl REG_VAR(reg)
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|     CFI_ADJUST_CFA_OFFSET(-4)
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| END_MACRO
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| 
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| MACRO1(SETUP_PC_REL_BASE_0, reg)
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|     SETUP_PC_REL_BASE_IMPL \reg, 0, 0f
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| END_MACRO
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| 
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| MACRO2(SETUP_PC_REL_BASE, reg, label)
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|     SETUP_PC_REL_BASE_IMPL \reg, \label, \label
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| END_MACRO
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| 
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| MACRO1(LOAD_RUNTIME_INSTANCE, reg)
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|     SETUP_PC_REL_BASE_0 \reg
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|     // Load Runtime::instance_.
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|     movl SYMBOL(_ZN3art7Runtime9instance_E) - 0b(REG_VAR(reg)), REG_VAR(reg)
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| END_MACRO
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| 
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| // Macros to poison (negate) the reference for heap poisoning.
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| MACRO1(POISON_HEAP_REF, rRef)
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| #ifdef USE_HEAP_POISONING
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|     neg REG_VAR(rRef)
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| #endif  // USE_HEAP_POISONING
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| END_MACRO
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| 
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| // Macros to unpoison (negate) the reference for heap poisoning.
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| MACRO1(UNPOISON_HEAP_REF, rRef)
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| #ifdef USE_HEAP_POISONING
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|     neg REG_VAR(rRef)
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| #endif  // USE_HEAP_POISONING
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| END_MACRO
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| 
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|     /*
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|      * Macro that sets up the callee save frame to conform with
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|      * Runtime::CreateCalleeSaveMethod(kSaveRefsOnly)
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|      */
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| MACRO1(SETUP_SAVE_REFS_ONLY_FRAME, temp_reg)
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|     PUSH edi  // Save callee saves (ebx is saved/restored by the upcall)
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|     PUSH esi
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|     PUSH ebp
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|     subl MACRO_LITERAL(12), %esp  // Grow stack by 3 words.
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|     CFI_ADJUST_CFA_OFFSET(12)
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|     LOAD_RUNTIME_INSTANCE \temp_reg
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|     // Push save all callee-save method.
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|     pushl RUNTIME_SAVE_REFS_ONLY_METHOD_OFFSET(REG_VAR(temp_reg))
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|     CFI_ADJUST_CFA_OFFSET(4)
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|     // Store esp as the top quick frame.
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|     movl %esp, %fs:THREAD_TOP_QUICK_FRAME_OFFSET
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| 
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|     // Ugly compile-time check, but we only have the preprocessor.
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|     // Last +4: implicit return address pushed on stack when caller made call.
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| #if (FRAME_SIZE_SAVE_REFS_ONLY != 3*4 + 16 + 4)
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| #error "FRAME_SIZE_SAVE_REFS_ONLY(X86) size not as expected."
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| #endif
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| END_MACRO
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| 
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| MACRO0(RESTORE_SAVE_REFS_ONLY_FRAME)
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|     addl MACRO_LITERAL(16), %esp  // Unwind stack up to saved values
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|     CFI_ADJUST_CFA_OFFSET(-16)
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|     POP ebp  // Restore callee saves (ebx is saved/restored by the upcall)
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|     POP esi
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|     POP edi
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| END_MACRO
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| 
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|     /*
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|      * Macro that sets up the callee save frame to conform with
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|      * Runtime::CreateCalleeSaveMethod(kSaveAllCalleeSaves)
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|      */
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| MACRO1(SETUP_SAVE_ALL_CALLEE_SAVES_FRAME, temp_reg)
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|     PUSH edi  // Save callee saves (ebx is saved/restored by the upcall)
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|     PUSH esi
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|     PUSH ebp
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|     subl MACRO_LITERAL(12), %esp  // Grow stack by 3 words.
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|     CFI_ADJUST_CFA_OFFSET(12)
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|     LOAD_RUNTIME_INSTANCE \temp_reg
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|     // Push save all callee-save method.
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|     pushl RUNTIME_SAVE_ALL_CALLEE_SAVES_METHOD_OFFSET(REG_VAR(temp_reg))
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|     CFI_ADJUST_CFA_OFFSET(4)
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|     // Store esp as the top quick frame.
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|     movl %esp, %fs:THREAD_TOP_QUICK_FRAME_OFFSET
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|     // Ugly compile-time check, but we only have the preprocessor.
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|     // Last +4: implicit return address pushed on stack when caller made call.
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| #if (FRAME_SIZE_SAVE_ALL_CALLEE_SAVES != 3*4 + 16 + 4)
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| #error "FRAME_SIZE_SAVE_ALL_CALLEE_SAVES(X86) size not as expected."
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| #endif
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| END_MACRO
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| 
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|     /*
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|      * Macro that sets up the callee save frame to conform with
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|      * Runtime::CreateCalleeSaveMethod(kSaveRefsAndArgs), except for pushing the method
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|      */
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| MACRO0(SETUP_SAVE_REFS_AND_ARGS_FRAME_REGISTERS_ONLY)
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|     PUSH edi      // Save callee saves
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|     PUSH esi
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|     PUSH ebp
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|     PUSH_ARG ebx  // Save args.
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|     PUSH_ARG edx
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|     PUSH_ARG ecx
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|     // Create space for FPR args.
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|     INCREASE_FRAME 4 * 8
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|     // Save FPRs.
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|     movsd %xmm0, 0(%esp)
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|     movsd %xmm1, 8(%esp)
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|     movsd %xmm2, 16(%esp)
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|     movsd %xmm3, 24(%esp)
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| 
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|     // Ugly compile-time check, but we only have the preprocessor.
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|     // First +4: implicit return address pushed on stack when caller made call.
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|     // Last +4: we're not pushing the method on the stack here.
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| #if (FRAME_SIZE_SAVE_REFS_AND_ARGS != 4 + 6*4 + 4*8 + 4)
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| #error "FRAME_SIZE_SAVE_REFS_AND_ARGS(X86) size not as expected."
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| #endif
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| END_MACRO
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| 
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| MACRO0(RESTORE_SAVE_REFS_AND_ARGS_FRAME)
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|     // Restore FPRs. EAX is still on the stack.
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|     movsd 4(%esp), %xmm0
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|     movsd 12(%esp), %xmm1
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|     movsd 20(%esp), %xmm2
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|     movsd 28(%esp), %xmm3
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| 
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|     DECREASE_FRAME 36             // Remove FPRs and method pointer.
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| 
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|     POP_ARG ecx                   // Restore args
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|     POP_ARG edx
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|     POP_ARG ebx
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|     POP ebp                       // Restore callee saves
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|     POP esi
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|     POP edi
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| END_MACRO
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| 
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|     /*
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|      * Macro that calls through to artDeliverPendingExceptionFromCode, where the pending
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|      * exception is Thread::Current()->exception_ when the runtime method frame is ready.
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|      */
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| MACRO0(DELIVER_PENDING_EXCEPTION_FRAME_READY)
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|     // Outgoing argument set up
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|     INCREASE_FRAME 12                          // alignment padding
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|     pushl %fs:THREAD_SELF_OFFSET               // pass Thread::Current()
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|     CFI_ADJUST_CFA_OFFSET(4)
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|     call SYMBOL(artDeliverPendingExceptionFromCode)  // artDeliverPendingExceptionFromCode(Thread*)
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|     UNREACHABLE
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|     CFI_ADJUST_CFA_OFFSET(-16)                 // Reset CFA in case there is more code afterwards.
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| END_MACRO
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| 
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|     /*
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|      * Macro that calls through to artDeliverPendingExceptionFromCode, where the pending
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|      * exception is Thread::Current()->exception_.
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|      */
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| MACRO0(DELIVER_PENDING_EXCEPTION)
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|     SETUP_SAVE_ALL_CALLEE_SAVES_FRAME ebx      // save callee saves for throw
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|     DELIVER_PENDING_EXCEPTION_FRAME_READY
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| END_MACRO
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| 
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| MACRO0(RETURN_OR_DELIVER_PENDING_EXCEPTION)
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|     cmpl MACRO_LITERAL(0),%fs:THREAD_EXCEPTION_OFFSET // exception field == 0 ?
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|     jne 1f                                            // if exception field != 0 goto 1
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|     ret                                               // return
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| 1:                                                    // deliver exception on current thread
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|     DELIVER_PENDING_EXCEPTION
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| END_MACRO
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| 
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| // Locking is needed for both managed code and JNI stubs.
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| MACRO4(LOCK_OBJECT_FAST_PATH, obj, tmp, saved_eax, slow_lock)
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| 1:
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|     movl MIRROR_OBJECT_LOCK_WORD_OFFSET(REG_VAR(obj)), %eax  // EAX := lock word
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|     movl %fs:THREAD_ID_OFFSET, REG_VAR(tmp)  // tmp: thread id.
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|     xorl %eax, REG_VAR(tmp)               // tmp: thread id with count 0 + read barrier bits.
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|     testl LITERAL(LOCK_WORD_GC_STATE_MASK_SHIFTED_TOGGLED), %eax  // Test the non-gc bits.
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|     jnz  2f                               // Check if unlocked.
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|     // Unlocked case - store tmp: original lock word plus thread id, preserved read barrier bits.
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|                                           // EAX: old val, tmp: new val.
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|     lock cmpxchg REG_VAR(tmp), MIRROR_OBJECT_LOCK_WORD_OFFSET(REG_VAR(obj))
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|     jnz  1b                               // cmpxchg failed retry
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|     .ifnc \saved_eax, none
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|         movl REG_VAR(saved_eax), %eax     // Restore EAX.
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|     .endif
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|     ret
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| 2:  // EAX: original lock word, tmp: thread id ^ EAX
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|                                           // Check lock word state and thread id together,
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|     testl LITERAL(LOCK_WORD_STATE_MASK_SHIFTED | LOCK_WORD_THIN_LOCK_OWNER_MASK_SHIFTED), \
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|           REG_VAR(tmp)
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|     jne  \slow_lock                       // Slow path if either of the two high bits are set.
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|                                           // Increment the recursive lock count.
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|     leal LOCK_WORD_THIN_LOCK_COUNT_ONE(%eax), REG_VAR(tmp)
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|     testl LITERAL(LOCK_WORD_THIN_LOCK_COUNT_MASK_SHIFTED), REG_VAR(tmp)
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|     jz   \slow_lock                       // If count overflowed, go to slow lock.
 | |
|     // Update lockword for recursive lock, cmpxchg necessary for read barrier bits.
 | |
|                                           // EAX: old val, tmp: new val.
 | |
|     lock cmpxchg REG_VAR(tmp), MIRROR_OBJECT_LOCK_WORD_OFFSET(REG_VAR(obj))
 | |
|     jnz  1b                               // cmpxchg failed retry
 | |
|     .ifnc \saved_eax, none
 | |
|         movl REG_VAR(saved_eax), %eax     // Restore EAX.
 | |
|     .endif
 | |
|     ret
 | |
| END_MACRO
 | |
| 
 | |
| // Unlocking is needed for both managed code and JNI stubs.
 | |
| MACRO4(UNLOCK_OBJECT_FAST_PATH, obj, tmp, saved_eax, slow_unlock)
 | |
| 1:
 | |
|     movl MIRROR_OBJECT_LOCK_WORD_OFFSET(REG_VAR(obj)), %eax  // EAX := lock word
 | |
|     movl %fs:THREAD_ID_OFFSET, REG_VAR(tmp)  // tmp := thread id
 | |
|     xorl %eax, REG_VAR(tmp)               // tmp := thread id ^ lock word
 | |
|     test LITERAL(LOCK_WORD_GC_STATE_MASK_SHIFTED_TOGGLED), REG_VAR(tmp)
 | |
|     jnz  2f                               // Check if simply locked.
 | |
|     // Transition to unlocked.
 | |
| #ifndef USE_READ_BARRIER
 | |
|     movl REG_VAR(tmp), MIRROR_OBJECT_LOCK_WORD_OFFSET(REG_VAR(obj))
 | |
| #else
 | |
|     lock cmpxchg REG_VAR(tmp), MIRROR_OBJECT_LOCK_WORD_OFFSET(REG_VAR(obj))
 | |
|     jnz  1b                               // cmpxchg failed retry
 | |
| #endif
 | |
|     .ifnc \saved_eax, none
 | |
|         movl REG_VAR(saved_eax), %eax     // Restore EAX.
 | |
|     .endif
 | |
|     ret
 | |
| 2:  // EAX: original lock word, tmp: lock_word ^ thread id
 | |
|                                           // Check lock word state and thread id together.
 | |
|     testl LITERAL(LOCK_WORD_STATE_MASK_SHIFTED | LOCK_WORD_THIN_LOCK_OWNER_MASK_SHIFTED), \
 | |
|           REG_VAR(tmp)
 | |
|     jnz  \slow_unlock
 | |
|     // Update lockword for recursive unlock, cmpxchg necessary for read barrier bits.
 | |
|                                           // tmp: new lock word with decremented count.
 | |
|     leal -LOCK_WORD_THIN_LOCK_COUNT_ONE(%eax), REG_VAR(tmp)
 | |
| #ifndef USE_READ_BARRIER
 | |
|     movl REG_VAR(tmp), MIRROR_OBJECT_LOCK_WORD_OFFSET(REG_VAR(obj))
 | |
| #else
 | |
|     lock cmpxchg REG_VAR(tmp), MIRROR_OBJECT_LOCK_WORD_OFFSET(REG_VAR(obj))
 | |
|     jnz  1b                               // cmpxchg failed retry
 | |
| #endif
 | |
|     .ifnc \saved_eax, none
 | |
|         movl REG_VAR(saved_eax), %eax     // Restore EAX.
 | |
|     .endif
 | |
|     ret
 | |
| END_MACRO
 | |
| 
 | |
| #endif  // ART_RUNTIME_ARCH_X86_ASM_SUPPORT_X86_S_
 |