15 213 The course that gives CMU its Zip Machine Level Programming I Introduction Jan 22 2008 Topics Assembly Programmer s Execution Model Accessing Information class04 ppt Registers Memory Arithmetic operations 15 213 S 08 Synchronization Lab 1 Time roughly 50 done Many have started early and made good progress Good Warning to others This isn t the same kind of thing you ve done before Please don t leave it to the last minute Fish machine log ins 2 Please let us know staff mailing list if you can t log in to any machine 15 213 S 08 Outline Some computer languages Whitespace Intercal M Some discussion of x86 x86 64 Warning Chapter 3 doesn t compress well 3 100 pages of discussion about machine language after 75 pages of data representation in Chapter 2 Please plan to spend time reading the text 15 213 S 08 A Whitespace Program Count from 1 to 10 partial listing Features of Whitespace 4 Only space tab and line feed encode program statements All other characters A Z a z 0 9 etc encode comments Simple stack based language 15 213 S 08 Whitespace Explained Statement Space Space Space Tab LF LF Space Space Space Tab Space Space Space Space Tab Tab LF Space LF Space Tab LF Space Tab 5 Meaning Push 1 onto stack Set a label at this point Duplicate the top stack item Output the current value 15 213 S 08 INTERCAL Features of INTERCAL Designed late one night in 1972 by two Princeton students Deliberately obfuscated language Variables 16 bit integers 1 through 65535 32 bit integers 1 through 65535 Operators Binary mingle select Unary AND OR XOR Simplest way to put 65536 in a 32 bit variable 6 How are those unary Simple AND and s together adjacent bits in a word DO 1 0 256 15 213 S 08 The language M Features of M Also designed in the 1970 s More widely used than Whitespace INTERCAL Variables 32 bit integer variables A B C D DI F S SI One array M Valid subscripts range from near zero to a large number But most subscripts in that range will crash your program Statements 7 Lots of arithmetic and logical operations Input and output use a special statement called OUCH 15 213 S 08 A Program in M C Code int sum int x int y int t x y return t 8 M sum A M S 4 A M S 8 DONE 15 213 S 08 A Program in M C Code int sum int x int y int t x y return t M sum A M S 4 A M S 8 DONE Had enough of M 9 Too bad We ll study it for much of the semester Why 15 213 S 08 M is The Language of the Machines 10 15 213 S 08 Everything Else is Illusion 11 15 213 S 08 IA32 Processors Totally Dominate Computer Market Evolutionary Design Starting in 1978 with 8086 Added more features as time goes on Still support old features although obsolete Complex Instruction Set Computer CISC Many different instructions with many different formats 12 But only small subset encountered with Linux programs Hard to match performance of Reduced Instruction Set Computers RISC But Intel has done just that 15 213 S 08 x86 Evolution Programmer s View Abbreviated Name 8086 386 13 Date Transistors 1978 29K 16 bit processor Basis for IBM PC DOS Limited to 1MB address space DOS only gives you 640K 1985 275K Extended to 32 bits Added flat addressing Capable of running Unix Referred to as IA32 32 bit Linux gcc uses no instructions introduced in later models 15 213 S 08 x86 Evolution Programmer s View Machine Evolution 486 Pentium Pentium MMX PentiumPro Pentium III Pentium 4 1989 1993 1997 1995 1999 2001 1 9M 3 1M 4 5M 6 5M 8 2M 42M Added Features Instructions to support multimedia operations Parallel operations on 1 2 and 4 byte data both integer FP Instructions to enable more efficient conditional operations Linux GCC Evolution 14 None 15 213 S 08 New Species IA64 Name Date Transistors Itanium 2001 10M Extends to IA64 a 64 bit architecture Radically new instruction set designed for high performance Can run existing IA32 programs On board x86 engine Joint project with Hewlett Packard Itanium 2 2002 221M Big performance boost Itanium 2 Dual Core 2006 1 7B Itanium has not taken off in marketplace Lack of backward compatibility 15 15 213 S 08 X86 Evolution Clones Advanced Micro Devices AMD Historically Recently Recruited top circuit designers from Digital Equipment Corp and other downward trending companies Exploited fact that Intel distracted by IA64 Now are close competitors to Intel Developed x86 64 its own extension to 64 bits 16 AMD has followed just behind Intel A little bit slower a lot cheaper Started eating into Intel s high end server market 15 213 S 08 Intel s 64 Bit Dilemma Intel Attempted Radical Shift from IA32 to IA64 Totally different architecture Executes IA32 code only as legacy Performance disappointing AMD Stepped in with Evolutionary Solution x86 64 now called AMD64 Intel Felt Obligated to Focus on IA64 Hard to admit mistake or that AMD is better 2004 Intel Announces EM64T extension to IA32 17 Extended Memory 64 bit Technology Almost identical to x86 64 Our Saltwater fish machines 15 213 S 08 Our Coverage IA32 The traditional x86 x86 64 The emerging standard Presentation Book has IA32 Handout has x86 64 Lecture will cover both Labs Lab 2 x86 64 Lab 3 IA32 18 15 213 S 08 Assembly Programmer s View CPU Memory Addresses Registers P C Object Code Program Data OS Data Data Condition Codes Instructions Programmer Visible State PC Program Counter Address of next instruction Called EIP IA32 or RIP x8664 Register File Heavily used program data Condition Codes 19 Stack Store status information about most recent arithmetic operation Used for conditional branching Memory Byte addressable array Code user data some OS data Includes stack used to support procedures 15 213 S 08 Turning C into Object Code Code in files Compile with command gcc O p1 c p2 c o p p1 c p2 c Use optimizations O Put resulting binary in file p text C program p1 c p2 c Compiler gcc S text Asm program p1 s p2 s Assembler gcc or as binary Object program p1 o p2 o Static libraries a Linker gcc or ld binary 20 Executable program p 15 213 S 08 Compiling Into Assembly C Code int sum int x int y int t x y return t Generated IA32 Assembly sum pushl ebp movl esp ebp movl 12 ebp eax addl 8 ebp eax movl ebp esp popl ebp ret Obtain with command gcc O S code c Produces file code s 21 15 213 S 08 Assembly Characteristics Minimal Data Types Integer data of 1 2 or 4 bytes Data values Addresses untyped pointers Floating point data of 4 8 or 10 bytes No aggregate types such as arrays or structures Just contiguously allocated bytes in memory Primitive Operations …
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