| Message ID | 4E849556.5010901@mentor.com |
|---|---|
| State | New |
| Headers | show |
On Thu, Sep 29, 2011 at 5:57 PM, Tom de Vries <Tom_deVries@mentor.com> wrote: > Richard, > > in gimplify_vla_decl, the alloca argument seems to be the size of the vla in units: > ... > t = build_call_expr (t, 1, DECL_SIZE_UNIT (decl)); > ... > > I wonder why we are going through this 8 vs. BITS_PER_UNIT conversion here: > ... > elem_type = build_nonstandard_integer_type (BITS_PER_UNIT, 1); > n_elem = size * 8 / BITS_PER_UNIT; > align = MIN (size * 8, BIGGEST_ALIGNMENT); > ... > The element size is BITS_PER_UNIT, so 1 unit, and size is in units. No, the size is in bytes and the gimplify code lacks the conversion. Richard. > > Shouldn't this be: > ... > Index: tree-ssa-ccp.c > =================================================================== > --- tree-ssa-ccp.c (revision 179210) > +++ tree-ssa-ccp.c (working copy) > @@ -1722,8 +1722,8 @@ fold_builtin_alloca_for_var (gimple stmt > > /* Declare array. */ > elem_type = build_nonstandard_integer_type (BITS_PER_UNIT, 1); > - n_elem = size * 8 / BITS_PER_UNIT; > - align = MIN (size * 8, BIGGEST_ALIGNMENT); > + n_elem = size; > + align = MIN (size * BITS_PER_UNIT, BIGGEST_ALIGNMENT); > if (align < BITS_PER_UNIT) > align = BITS_PER_UNIT; > array_type = build_array_type_nelts (elem_type, n_elem); > ... > > Thanks, > - Tom >
Index: tree-ssa-ccp.c =================================================================== --- tree-ssa-ccp.c (revision 179210) +++ tree-ssa-ccp.c (working copy) @@ -1722,8 +1722,8 @@ fold_builtin_alloca_for_var (gimple stmt /* Declare array. */ elem_type = build_nonstandard_integer_type (BITS_PER_UNIT, 1); - n_elem = size * 8 / BITS_PER_UNIT; - align = MIN (size * 8, BIGGEST_ALIGNMENT); + n_elem = size; + align = MIN (size * BITS_PER_UNIT, BIGGEST_ALIGNMENT); if (align < BITS_PER_UNIT) align = BITS_PER_UNIT; array_type = build_array_type_nelts (elem_type, n_elem);