gcc, gnu compiler collection

1. GCC : GNU compilers collection Alberto Bustamante Reyes (www.albertobustamante.com) Author:

2. Brief introduction

Compiler system developed by GNU Project

3. Distributed by FSF under GPL License 4. Written in C / C++ 5. Default compiler for Unix and Mac OS X 6. Also ported to Windows (MinGW) 7. Brief introduction

Originally developed for C language

8. Several front-ends added to support different languages:

C / C++(gcc / g++)

9. Java(gcj)

10. Objective-C / Objective-C++(gobjc / gobjc++ ) 11. Fortran(gfortran) 12. Structure

Generic compiler:

Front end

13. Back end

GCC compiler:

Front end

14. Middle end

15. Back end 16. Structure

GCC Compiler (before 2005)

Source code AST RTL RTL Object code FRONT END BACK END 17. Structure

Source code AST RTL RTL Object code FRONT END BACK END 18. Structure

Source code AST RTL RTL Object code FRONT END BACK END SSA Tree project: OPTIMIZATIONS 19. Structure

GCC Compiler (after 2005)

Source code AST GENERIC GIMPLE RTL FRONT END 20. Structure

Source code AST GENERIC GIMPLE RTL FRONT END Language dependent Language independent 21. Structure

Source code AST GENERIC GIMPLE RTL FRONT END Language dependent Language independent MIDDLE END 22. Structure: GENERIC & GIMPLE

Why two kinds of trees?

GIMPLE is a simplified subset of GENERIC

GIMPLE GENERIC 23. Structure: GENERIC & GIMPLE

GENERIC -> (Gimplifier) -> GIMPLE

GIMPLIFIER if (foo ( a + b, c)) c = b ++ / a end if return c t1 = a +b t2 = foo (t1, c) If (t2 != 0 ) L1: t3 = b b = b + 1 c = t3 / a goto L3 L2: L3: return c 24. Structure: GENERIC & GIMPLE

Developed by SSA Tree Project

25. SSA

Developed by IBM in 1980

26. Single Static Assignment

27. Example: y := 1 y := 2 x := y y1 := 1 y2 := 2 x1 := y2 28. Structure: Middle end GIMPLETree SSA OptimizerRTL 29. Structure:Middle end

SSA Tree Optimization

Dead code elimination

y := 1 y := 2 x := y y1 := 1 y2 := 2 x1 := y2 30. Structure:Middle end

31. Partial redundancy elimination

if (some_condition) { // some code y = x + 4; }else { // other code } z = x + 4; if (some_condition) { // some code y = x + 4; t = y; }else { // other code t = x + 4; } z = t; 32. Structure:Middle end

34. Global value numbering w := 3 x := 3 y := x + 4 z := w + 4 w := 3 x := w y := w + 4 z := y 35. Structure:Middle end

37. Global value numbering 38. Sparse conditional constant propagation 39. Structure:Middle end

41. Global value numbering 42. Sparse conditional constant propagation 43. Scalar replacement of aggregates 44. Structure: RTL

Output of the Middle End

45. Processor dependent 46. Looks like Lisp S-expressions: (set:SI (reg:SI 140) (plus:SI (reg:SI 138) (reg:SI 139))) 47. Structure: summary Source code AST GENERIC GIMPLETree SSA Optimizer RTL Optimized RTLObject code FRONT END MIDDLE END BACK END 48. Advantages of using GCC

Reliable

Suppported by GNU & FSF

49. Active and noumerous developer team

50. One of the most popular compilers 51. Lots of test cases (users)

Several front ends

52. Free!! 53. More information available at

GCC :http://gcc.gnu.org

54. GCC Wiki :http://gcc.gnu.org/wiki 55. SSA Tree Project:http://gcc.gnu.org/projects/tree-ssa/ 56. GNU :http://www.gnu.org 57. Free Software Foundation :http://www.fsf.org 58. MinGW:http://www.mingw.org 59. The End Thanks for watching 60. GCC : GNU compilers collection Alberto Bustamante Reyes (www.albertobustamante.com) Author:

gcc, gnu compiler collection

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