Transcript Languages and the Machine

Chapter 5 - Languages and the Machine
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Principles of Computer Architecture
Miles Murdocca and Vincent Heuring
Chapter 5: Languages and the
Machine
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Chapter 5 - Languages and the Machine
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Chapter Contents
5.1 The Compilation Process
5.2 The Assembly Process
5.3 Linking and Loading
5.4 Macros
5.5 Case Study: Extensions to the Instruction Set – The Intel
MMX™ and Motorola AltiVec™ SIMD Instructions
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Chapter 5 - Languages and the Machine
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The Compilation Process
• Compilation translates a program written in a high level language
into a functionally equivalent program in assembly language.
• Consider a simple high-level language assignment statement:
A = B + 4;
• Steps involved in compiling this statement into assemby code:
— Reducing the program text to the basic symbols of the language
(for example, into identifiers such as A and B), denotations such
as the constant value 4, and program delimiters such as = and +.
This portion of compilation is referred to as lexical analysis.
— Parsing symbols to recognize the underlying program structure.
For the statement above, the parser must recognize the form:
Identifier “=” Expression,
where Expression is further parsed into the form:
Identifier “+” Constant.
Parsing is sometimes called syntactic analysis.
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The Compilation Process
— Name analysis: associating the names A and B with particular
program variables, and further associating them with particular
memory locations where the variables are located at run time.
— Type analysis: determining the types of all data items. In the
example above, variables A and B and constant 4 would be
recognized as being of type int in some languages. Name and
type analysis are sometimes referred to together as semantic
analysis: determining the underlying meaning of program
components.
— Action mapping and code generation: associating program
statements with their appropriate assembly language sequence.
In the statement above, the assembly language sequence might
be as follows:
ld [B], %r0, %r1
! Get variable B into a register.
add %r1, 4, %r2
! Compute the value of the expression
st %r2, %r0, [A]
! Make the assignment.
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The Assembly Process
• The process of translating an assembly language program into a
machine language program is referred to as the assembly process.
• Production assemblers generally provide this support:
— Allow programmer to specify locations of data and code.
— Provide assembly-language mnemonics for all machine
instructions and addressing modes, and translate valid assembly
language statements into the equivalent machine language.
— Permit symbolic labels to represent addresses and constants.
— Provide a means for the programmer to specify the starting
address of the program, if there is one; and provide a degree of
assemble-time arithmetic.
— Include a mechanism that allows variables to be defined in one
assembly language program and used in another, separately
assembled program.
— Support macro expansion.
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Assembly Example
• We explore how the assembly process proceeds by “hand
assembling” a simple ARC assembly language program.
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Chapter 5 - Languages and the Machine
Instruction
Formats
and
PSR
Format
for the
ARC
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Assembled Code
ld [x], %r1
1100 0010 0000 0000 0010 1000 0001 0100
ld [y], %r2
1100 0100 0000 0000 0010 1000 0001 1000
addcc %r1,%r2,%r3 1000 0110 1000 0000 0100 0000 0000 0010
st %r3, [z]
1100 0110 0010 0000 0010 1000 0001 1100
jmpl %r15+4, %r0
1000 0001 1100 0011 1110 0000 0000 0100
15
0000 0000 0000 0000 0000 0000 0000 1111
9
0000 0000 0000 0000 0000 0000 0000 1001
0
0000 0000 0000 0000 0000 0000 0000 0000
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Forward Referencing
• An example of forward referencing:
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Chapter 5 - Languages and the Machine
Assembled
Program
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Chapter 5 - Languages and the Machine
Linking: Using .global and .extern
• A .global is used in the module where a symbol is defined and a
.extern is used in every other module that refers to it.
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Chapter 5 - Languages and the Machine
Linking and Loading: Symbol Tables
• Symbol tables for the previous example:
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Chapter 5 - Languages and the Machine
Example ARC
Program
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Macro Definition
• A macro definition for push:
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Recursive Macro Expansion
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Intel MMX (MultiMedia eXtensions)
• Vector addition of eight bytes by the Intel PADDB mm0, mm1
instruction:
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• Intel “aliases” the
floating point
registers as MMX
registers. This means
that the Pentium’s 8
64-bit floating-point
registers do doubleduty as MMX
registers.
Chapter 5 - Languages and the Machine
Intel and Motorola
Vector Registers
• Motorola implements
32 128-bit vector
registers as a new set,
separate and distinct
from the floating-point
registers.
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MMX and AltiVec Arithmetic
Instructions
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Chapter 5 - Languages and the Machine
Comparing Two MMX Byte Vectors for
Equality
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Conditional Assignment of an MMX
Byte Vector
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Addressing Modes
Chapter 5 - Languages and the Machine
• Four ways of computing the address of a value in memory: (1) a
constant value known at assembly time, (2) the contents of a register,
(3) the sum of two registers, (4) the sum of a register and a constant.
The table gives names to these and other addressing modes.
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Subroutine Linkage – Registers
• Subroutine linkage with registers passes parameters in registers.
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Chapter 5 - Languages and the Machine
Subroutine Linkage – Data Link Area
• Subroutine linkage with a data link area passes parameters in a
separate area in memory. The address of the memory area is
passed in a register (%r5 here).
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Subroutine Linkage – Stack
• Subroutine linkage with a stack passes parameters on a stack.
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Chapter 5 - Languages and the Machine
Stack
Linkage
Example
• A C program
illustrates
nested function
calls.
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Chapter 5 - Languages and the Machine
Stack
Linkage
Example
(cont’)
• (a-f) Stack
behavior during
execution of the
program shown
in previous slide.
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Chapter 5 - Languages and the Machine
Stack
Linkage
Example
(cont’)
• (g-k) Stack
behavior during
execution of the C
program shown
previously.
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Chapter 5 - Languages and the Machine
Input and
Output for
the ISA
• Memory map for
the ARC, showing
memory mapped
I/O.
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Touchscreen I/O Device
• A user selecting an object on a touchscreen:
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Chapter 5 - Languages and the Machine
Flowchart for I/O
Device
• Flowchart illustrating the
control structure of a program
that tracks a touchscreen.
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Java Virtual Machine Architecture
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Chapter 5 - Languages and the Machine
Java
Program
and
Compiled
Class
File
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A Java Class File
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A Java Class File (Cont’)
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Byte Code for Java Program
• Disassembled byte code for previous Java program.
Location
0x00e3
0x00e4
0x00e5
0x00e6
0x00e7
0x00e8
0x00e9
0x00ea
0x00eb
0x00ec
0x00ed
0x00ee
0x00ef
Code
0x10
0x0f
0x3c
0x10
0x09
0x3d
0x03
0x3e
0x1b
0x1c
0x60
0x3e
0xb1
Mnemonic
bipush
15
istore_1
bipush
9
istore_2
iconst_0
istore_3
iload_1
iload_2
iadd
istore_3
return
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Meaning
Push next byte onto stack
Argument to bipush
Pop stack to local variable 1
Push next byte onto stack
Argument to bipush
Pop stack to local variable 2
Push 0 onto stack
Pop stack to local variable 3
Push local variable 1 onto stack
Push local variable 2 onto stack
Add top two stack elements
Pop stack to local variable 3
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