CS 412/413
Introduction to Compilers

Supporting Material for the Code Generation Assignment

Example programs

• Hello world: hello.ic, hello.s
• Fibonacci computation: fib.ic, fib.s
• Objects example: objects.ic, objects.s


Calling conventions

• Function arguments pushed on stack in reverse order
• Return value stored in eax register (not on stack)
• Caller-saved registers: eax, ecx, edx
• Callee-saved registers: ebx, esi, edi, ebp, esp
  

Pentium Instruction Set Architecture

• A quick description of the Pentium Instruction Set (taken from the nasm assembler documentation; uses Intel syntax)
  
• Complete documentation: Intel Manuals page, which includes:
• Intel Architecture Optimizations Manual
• Intel Architecture Software Developer's Manual, Volume 1: Basic Architecture
• Intel Architecture Software Developer's Manual, Volume 2: Instruction Set Reference Manual
• Intel Architecture Software Developer's Manual, Volume 3: System Programming Guide
  

GNU Assembler

• Documentation for the as assembler: Postscript, HTML (uses the AT&T syntax)
  

AT&T versus Intel Syntax

	AT&T	Intel
Order of operands	op a,b  means  b = a op b  (second operand is destination)	op a, b   means  a = a op b (first operand is destination)
Memory addressing	disp(base, offset, scale)	[base + offset*scale + disp]
Size of memory operands	instruction suffixes (b,w,l) (e.g., movb, movw, movl)	operand prefixes (e.g., byte ptr, word ptr, dword ptr)
Registers	%eax, %ebx, etc.	eax, ebx, etc.
Constants	$4, $foo, etc	4, foo, etc

Assembling and linking commands

In Windows under the Cygwin environment, the assembling and linking commands for an assembly file "file.s" are:

as -o file.o file.s
ld -o file.exe file.o /lib/crt0.o libic.a -lcygwin -lkernel32

The library file libic.a for Windows/Cygwin is a collection of .o files bundled together, containing the code for all of the library functions defined in the language specification, along with run-time support for garbage collection. 

The IC library is also available for Linux: libic.linux.a. The assembling and linking commands for "file.s" in Linux are:

as -o file.o file.s
ld -o file file.o /usr/lib/crt1.o /usr/lib/crti.o libic.linux.a -lc /usr/lib/crtn.o -dynamic /lib/ld-linux.so.2