From dbb9c2b1f231262ece36790241fe1fc3902cf03d Mon Sep 17 00:00:00 2001 From: Joel Brobecker Date: Wed, 26 Feb 2014 10:53:05 -0800 Subject: [PATCH] Add comment in dwarf2read.c::read_subrange_type This comment explains why we sometimes sign-extend the range type bounds when we normally shouldn't have to. gdb/ChangeLog: * dwarf2read.c (read_subrange_type): Add comment. --- gdb/ChangeLog | 4 ++++ gdb/dwarf2read.c | 7 +++++++ 2 files changed, 11 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 8f2f0dcfef5..49d81132430 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,7 @@ +2014-02-27 Joel Brobecker + + * dwarf2read.c (read_subrange_type): Add comment. + 2014-02-27 Joel Brobecker * dwarf2read.c (update_enumeration_type_from_children): New diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index 00bba472ada..52208d6dd5e 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -14522,6 +14522,13 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu) } } + /* Normally, the DWARF producers are expected to use a signed + constant form (Eg. DW_FORM_sdata) to express negative bounds. + But this is unfortunately not always the case, as witnessed + with GCC, for instance, where the ambiguous DW_FORM_dataN form + is used instead. To work around that ambiguity, we treat + the bounds as signed, and thus sign-extend their values, when + the base type is signed. */ negative_mask = (LONGEST) -1 << (TYPE_LENGTH (base_type) * TARGET_CHAR_BIT - 1); if (!TYPE_UNSIGNED (base_type) && (low & negative_mask)) -- 2.30.2