On 30/08/2024 18:11, Alex Coplan wrote:
> Hi,
>
> vec.h has this method:
>
> template<typename T, typename A>
> inline T *
> vec_safe_push (vec<T, A, vl_embed> *&v, const T &obj CXX_MEM_STAT_INFO)
>
> where v is a reference to a pointer to vec. This matches the regex for
> VecPrinter, so gdbhooks.py attempts to print it but chokes on the reference.
> I see the following:
>
> #1 0x0000000002b84b7b in vec_safe_push<edge_def*, va_gc> (v=Traceback (most
> recent call last):
> File "$SRC/gcc/gcc/gdbhooks.py", line 486, in to_string
> return '0x%x' % intptr(self.gdbval)
> File "$SRC/gcc/gcc/gdbhooks.py", line 168, in intptr
> return long(gdbval) if sys.version_info.major == 2 else int(gdbval)
> gdb.error: Cannot convert value to long.
>
> This patch makes VecPrinter handle such references by stripping them
> (dereferencing) at the top of the relevant functions.
>
> I thought about trying to make VecPrinter.{to_string,children} robust
> against non-pointer values (i.e. actual vec structs) as the current
> calls to intptr will fail on those. However, I then realised that the
> current regex only matches pointer types:
>
> pp.add_printer_for_regex(r'vec<(\S+), (\S+), (\S+)> \*',
> 'vec',
> VecPrinter)
>
> That is somewhat at odds with the (pre-existing) code in
> VecPrinter.children which appears to attempt to handle non-pointer
> types. ISTM either we should drop the handling for non-pointer types
> (since the regex requires a pointer) or (perhaps more usefully) relax
> the regex to allow matching a plain vec<...> struct and fix the member
> functions to handle those properly.
>
> Any thoughts on that, Dave? Is the current patch OK as an intermediate
> step (manually tested by verifying both a vec*& and vec* print OK)?
Gentle ping on this.
>
> Thanks,
> Alex
>
> gcc/ChangeLog:
>
> * gdbhooks.py (strip_ref): New. Use it ...
> (VecPrinter.to_string): ... here,
> (VecPrinter.children): ... and here.
> diff --git a/gcc/gdbhooks.py b/gcc/gdbhooks.py
> index 904ee28423a..a91e5fd2a83 100644
> --- a/gcc/gdbhooks.py
> +++ b/gcc/gdbhooks.py
> @@ -472,6 +472,11 @@ def get_vec_kind(val):
> else:
> assert False, f"unexpected vec kind {kind}"
>
> +def strip_ref(gdbval):
> + if gdbval.type.code == gdb.TYPE_CODE_REF:
> + return gdbval.referenced_value ()
> + return gdbval
> +
> class VecPrinter:
> # -ex "up" -ex "p bb->preds"
> def __init__(self, gdbval):
> @@ -483,10 +488,10 @@ class VecPrinter:
> def to_string (self):
> # A trivial implementation; prettyprinting the contents is done
> # by gdb calling the "children" method below.
> - return '0x%x' % intptr(self.gdbval)
> + return '0x%x' % intptr(strip_ref(self.gdbval))
>
> def children (self):
> - val = self.gdbval
> + val = strip_ref(self.gdbval)
> if intptr(val) != 0 and get_vec_kind(val) == VEC_KIND_PTR:
> val = val['m_vec']
>
