[LLVMdev] Kinda noob questions

[Judison]

Hi all,

I have 2 simple questions...

First, just for you to know, I'm making a compiler (kinda obvious) and the
language definition is mine, so there is no much constraint for me, it's
written in Java (it generates a .ll file as output) and it's just for fun by
now, maybe a serious project after I learn all the stuff needed...

and sorry bad english

1) I want to know if when I do this kind of thing:

entry:
%x = alloca i32
%y = alloca i32
... normal instructions...
other_block:
%z = alloca i32
....
br .... label %other_block

the stack "grows" when alloca is "called", or its the same as putting "%z =
alloca" in the beggining?
or... if alloca is in a loop, the stack grows every time it iterates??



2) does the LLVM optimizes this:

; this code (arg -> var) is very similar to what gcc generates
define void @foo(i32 %arg0) {
entry:
    %var0 = alloca i32
    store i32 %arg0, i32* var0
    ...
    %x = load i32* %var0
    ....
    ; never more stores to %var0 or pass it to any function
}

to something like:

define void @foo(i32 arg0) {
entry:
    ; no alloca
    ....
    %x = %arg0
   ....
}

does it???

I'm asking because I can check in my compiler if some arg is only readed or
if its used as a var before generate the IR, an then only create (alloca) a
%var if the arg is used for read-write :P (my language is "safe" (no
pointers))
If LLVM optimizes it, I'll let it... if not, I'll do this optimization

Thanks in advance :P

-- 
Judison
judison at gmail.com

"A wise man first thinks and then speaks and a fool speaks first and then
thinks." Imam Ali (as)
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