On 24 July 2016 at 21:26, Bin.Cheng <amker.ch...@gmail.com> wrote: > Hi, > I ran into a problem that C frontend (in function > build_conditional_expr) creates expression like (C_MAYBE_CONST_EXPR > (NULL, x + const)). The inner expression (and its operands) have > unsigned int type. After that, the expression needs to be casted to > result type which is unsigned short. In this case, > convert_to_integer/convert_to_integer_1 doesn't fold into > C_MAYBE_CONST_EXPR and just returns (unsigned > short)(C_MAYBE_CONST_EXPR (NULL, x + const)), as a result, (unsigned > short)(x + const) won't be simplified as (unsigned short)x + const. > My questions are, 1) Is it possible to fold type conversion into > C_MAYBE_CONST_EXPR's inner expression in convert_to_integer_1? 2) If > not, looks like there are couple of places the mentioned fold can be > done, for example, after stripping C_MAYBE_CONST_EXPR and before (or > during) gimplify. So which place is preferred? Sorry, I have a very silly question: I don't understand how the following transform (unsigned short) (x + const) to (unsigned short)x + const would be legal since the operands to PLUS_EXPR in latter case would have different types (unsigned short, unsigned) ? I suppose in GIMPLE (and GENERIC too?) we require rhs1 and rhs2 to have same types ?
Thanks, Prathamesh > > Thanks, > bin
