Let me try again. If I have an expression of the from a[i][10], then I need to insert the following function call into the tree: check_deref(a[i][10], sizeof(a[i][10]), &a[i][10]); I tried POINTER_PLUS_EXPR. It fails at the same place. However, it works if I have constant indices like a[1][10]. Hope this is clearer than before. Thanks! Zahed On Fri, Mar 9, 2012 at 7:48 PM, Ian Lance Taylor <iant@xxxxxxxxxx> wrote: > zahed khurasani <sdzahed@xxxxxxxxx> writes: > >> I need to build a node that is equivalent to the address of the memory >> being derenferenced. >> MEM_REF would help with the first parameter. But what about the third parameter? >> I would need an ADDR_EXPR for this parameter. However, the code I am using >> is failing. >> Thanks for the help. > > I'm not sure I completely understand, but I will say that a > POINTER_PLUS_EXPR would be the address equivalent of a MEM_REF. > > Ian > >> On Fri, Mar 9, 2012 at 6:04 PM, Ian Lance Taylor <iant@xxxxxxxxxx> wrote: >>> zahed khurasani <sdzahed@xxxxxxxxx> writes: >>> >>>> My check function accepts three parameters: the value being >>>> dereferenced, the size of the object and the address in memory. I am >>>> using the following two lines to get the third address parameter. >>>> >>>> addr = build1 (ADDR_EXPR, build_pointer_type (type), t); // t is the >>>> ARRAY_REF node >>>> fold_convert_loc(location, ptr_type_node, addr); // type case to void * >>>> >>>> However, this is failing whenever the array_ref contains a >>>> non-constant expression, say like a[i+1]. The specific failure is >>>> inside the expand_expr_real_1 method in the file expr.c. Looks like >>>> such non-constant indices are not allowed at this stage in the >>>> compilation (I've inserted the pass just before lowering to RTL >>>> happens). >>>> >>>> My question is, what would be the right way to get the address? I am >>>> looking for something that will preferably work for all dereferences >>>> like MEM_REF, INDIRECT_REF etc. >>> >>> ARRAY_REF certainly permits non-constant indices, so I don't think that >>> is your problem. >>> >>> However, MEM_REF is the most general memory reference expression. >>> >>> Ian
