Add chapter 10

chapter10/chapter10.md

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+# Chapter 10
+## Python optimizations
+In this chapter let us study about the optimizations performed by python and what is the
+programmers role.
+
+Create a sample file test.py with the following contents:
+
+```c
+if not 100:
+print "1000"
+else:
+print "100"
+```
+
+In the debug configurations add the following arguments:
+
+Open the file Python/peephole.c and open the line number 425 which is the function
+PyCode_Optimize which is the function that performs the peephole optimizations. This chapter
+is not an alternative to the optimizations that can be performed at the code level by the
+programmer. This chapter is just intended to show the kind of optimizations the compiler
+performs on the program.
+Insert a breakpoint on line number 494, which is a giant for loop which iterates through the
+entire code object instruction by instruction. On line number 364 we see a giant switch case to
+specify the kind of optimizations that are performed for any opcode. Let us step by debugging
+the individual lines.
+The first switch case is on the bytecode UNARY_NOT. Let us examine the code for the same.
+
+```c
+if (codestr[i+1] != POP_JUMP_IF_FALSE || !ISBASICBLOCK(blocks,i,4))
+    continue;
+j = GETARG(codestr, i+1);
+codestr[i] = POP_JUMP_IF_TRUE;
+SETARG(codestr, i, j);
+codestr[i+3] = NOP;
+goto reoptimize_current;
+```
+
+It replaces UNARY_NOT POP_JUMP_IF_FALSE by the bytecode POP_JUMP_IF_TRUE,
+which seems logical. From our code examine how the optimization is performed.
+
+Go through the individual cases to understand what kind of optimizations are performed for
+every individual instruction bytecodes. Adios :)