On Fri, 31 Jan 2020, Bin.Cheng wrote: > Hi, > In tree.c:build2 there is following code/comment: > > if ((code == MINUS_EXPR || code == PLUS_EXPR || code == MULT_EXPR) > && arg0 && arg1 && tt && POINTER_TYPE_P (tt) > /* When sizetype precision doesn't match that of pointers > we need to be able to build explicit extensions or truncations > of the offset argument. */ > && TYPE_PRECISION (sizetype) == TYPE_PRECISION (tt)) > gcc_assert (TREE_CODE (arg0) == INTEGER_CST > && TREE_CODE (arg1) == INTEGER_CST); > > The comment says specific condition needs to be satisfied if sizetype > precision doesn't match that of pointers, while the code is checking > "==" of precisions? Any explanation?
On targets where sizetype mode != ptr_mode the assert fires for reasons I do not remember. The comment is a bit confusing since we're dealing with plus/minus/mult here, not truncations or extensions also the assert will still allow to-be-constant-folded values (guess fold-const.c doesn't honor the restrictions). In reality minus/plus/mult should never be used on pointers. Richard.
