[LLVMdev] alloca & store generation

[Ryan M. Lefever]

I am writing a transformation that needs to add a call to a function F() 
at the beginning of main() with the addresses of argc and argv as 
parameters to F().  However, the bytecode file I'm transforming has not 
allocated space on the stack for argc and argv.  So, I developed my 
transformation to change main() from:

-----
int main(int %argc, sbyte** %argv){
entry:
   ...
   // some use of %argc and %argv
   ...
}
-----

to the following code:

-----
int main(int %argc, sbyte** %argv){
entry:
   %argc_addr = alloca int
   %argv_addr = alloca sbyte**
   store int %argc, int* %argc_addr
   store sbyte** %argv, sbyte*** %argv_addr
   call void %F ( int %argc_addr, sbyte*** %argv_addr )
   %tmp = load int* %argc_addr
   %tmp1 = load int* %tmp
   ...
   // the use of %argc and %argv is transformed to use
   // %tmp and %tmp1, respectively
   ...
}
-----

However, after adding the alloca and stores, I print out main it looks like:

-----
int %main(int %argc, sbyte** %argv) {
entry:
   alloca int              ; <int*>:0 [#uses=1]
   alloca sbyte**          ; <sbyte***>:0 [#uses=1]
   store int %argc, int* %0
   store sbyte** %argv, sbyte*** %0
   ...
-----

I used the following code in my transformation:

-----
   BasicBlock* eb = M.getMainFunction()->getEntryBlock();
   Function::arg_iterator argc_it = mainfun->arg_begin();
   Function::arg_iterator argv_it = argc_it;
   ++argv_it;
   Argument* argc = &*argc_it;
   Argument* argv = &*argv_it;
   Instruction* insertNewInstsBefore = &eb->front();
   AllocaInst* argc_alloca = new AllocaInst(argc->getType(), "",
					   insertNewInstsBefore);
   AllocaInst* argv_alloca = new AllocaInst(argv->getType(), "",
					   insertNewInstsBefore);
   new StoreInst(argc, argc_alloca, false, insertNewInstsBefore);
   new StoreInst(argv, argv_alloca, false, insertNewInstsBefore);
-----

Why isn't llvm giving a name to the value returned by the allocas and 
using it in the store instructions?

Regards,
Ryan