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Jmp graph builder points front6/19/2023 No notes here yet, for now, see Wikipedia. (2) the instruction before the target of a branch. (2) the instruction after a conditional branch Starts with: (1) target of a branch (label) or.To locate basic blocks in flattened code: in the abscence of hardware faults, interrupts, crashes, threading problems, etc. maximal-length code block with only one entry and one exit.maximal-length straight-line code block.maximal-length sequence of instructions that will execute in its entirety.Now that we’ve seen the basics of tuples, let’s see how they are stored and manipulated by a compiler.Ī control flow graph is a graph whose nodes are basic blocks and whose edges are transitions between blocks. TODO - bounds checking? allocation? Control Flow Graphs Temporaries differ from variables in that variables come from source language variables that are actually declared, while temporaries are the result of evaluating expressions. Note how tuples assume what is essentially an unlimited supply of registers. X (inclusive) (details left to the implementation) String representation of a boolean (localized?)Īllocate x bytes of memory, returning the address in y (or 0 if the memory could not be allocated).Īllocate x*elsize bytes of memory, where elsize is the number of bytes of an element in array x, returning the address in y (or 0 if the memory could not be allocated).ĭeallocate the memory at address x (or do nothing if x is 0)ĭo something if x is null (details left to the implementation)ĭo something if x is not positive (details left to the implementation)ĭo something if x is not between y (inclusive) and String representation of a float (one can add a new String representation of an integer (one can add a new Increment and jump if equal (useful at end of for-loops that count up to a given value)ĭecrement and jump if not zero (great for loops that count down to zero by one)Ĭall procedure (non-value returning function) f, with arguments x1. Jump if greater or equal / Jump if not less Increment a memory location given its addressĭecrement a memory location given its addressĬopy address of a into z identical to (ADD, a, i*elsize, x) where elsize is the size in bytes of the element type of array a.Ĭopy contents of memory at address a + i*elsize into x where elsize is the size in bytes of the element type of array aĬopy x into the memory at address a + i*elsize where elsize is the size in bytes of the element type of array aĬopy address of s.f into x identical to (ADD, s, ofs(f), x) where ofs(f) is the byte offset of field f in struct s.Ĭopy contents of memory at address s + ofs(f)Ĭopy x into the memory at address s + ofs(f) Here is the tuple representation of the example source code fragment above:ġ if x is greater than or equal to y 0 otherwiseĬopy contents of memory at address x into y Many folks would require a true IR to have some kind of lower level instruction lists. You can even reconstruct the text of the source code from it (up to differences in whitespace and comments). Some might not call this an IR, but rather simply a source program representation: it’s what the analyzer produces. The so-called semantic graph is is just an abstract syntax tree, analyzed, type checked, annotated and transformed into a graph: We’ll use a running example code fragment to illustrate various options. Intermediate representations come in many flavors.
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