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The additional files attached for internal compiler errors usually have special formats that they save as, such as .dump for Java. These formats are generally more difficult to analyze than regular files, but can still have very helpful information for solving the bug causing the crash.
If the language being compiled is type safe, the compiler's type checker is correct, and the language lacks the ability to create pointers referencing local variables, (such as ML, Haskell, or Java) then some useful optimizations can be made. [1] There are many cases where we know that two memory locations must be in different alias classes:
In some languages (e.g. Java [9]) some forms of unreachable code are explicitly disallowed. The optimization that removes unreachable code is known as dead code elimination . Code may become unreachable as a consequence of transformations performed by an optimizing compiler (e.g., common subexpression elimination ).
Heap modeling: Run-time allocations may be abstracted by: their allocation sites (the statement or instruction that performs the allocation, e.g., a call to malloc or an object constructor), a more complex model based on a shape analysis, the type of the allocation, or; one single allocation (this is called heap-insensitivity).
To optimize this, a C++ compiler would need to: Inline the sin and operator+ function calls. Fuse the loops into a single loop. Remove the unused stores into the temporary arrays (can use a register or stack variable instead). Remove the unused allocation and free. All of these steps are individually possible.
Here is an example of ANSI C code that will generally cause a segmentation fault on platforms with memory protection. It attempts to modify a string literal, which is undefined behavior according to the ANSI C standard. Most compilers will not catch this at compile time, and instead compile this to executable code that will crash:
In compiler optimization, register allocation is the process of assigning local automatic variables and expression results to a limited number of processor registers. Register allocation can happen over a basic block ( local register allocation ), over a whole function/ procedure ( global register allocation ), or across function boundaries ...
32-bit compilers emit, respectively: _f _g@4 @h@4 In the stdcall and fastcall mangling schemes, the function is encoded as _name@X and @name@X respectively, where X is the number of bytes, in decimal, of the argument(s) in the parameter list (including those passed in registers, for fastcall).