Determine endianness at a time when it doesn't inadvertantly clear gdb's wrap_buffer via gdb.execute.
Summary:
I haven't managed a small reproduction for this bug, it involves
complicated and deeply nested data structures with a wide variety
of pretty printers. But in general, we shouldn't be combining
gdb's command line interface (via gdb.execute) with pretty-printers.
Subscribers: christof, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68306
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@373402 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/gdb/libcxx/printers.py b/utils/gdb/libcxx/printers.py
index dc2f2e9..ff45bde 100644
--- a/utils/gdb/libcxx/printers.py
+++ b/utils/gdb/libcxx/printers.py
@@ -27,6 +27,7 @@
_long_int_type = gdb.lookup_type("unsigned long long")
+_libcpp_big_endian = False
def addr_as_long(addr):
return int(addr.cast(_long_int_type))
@@ -195,19 +196,14 @@
field = short_field.type.fields()[1].type.fields()[0]
libcpp_abi_alternate_string_layout = field.name and "__padding" in field.name
- # Strictly, this only tells us the current mode, not how libcxx was
- # compiled.
- libcpp_big_endian = "big endian" in gdb.execute("show endian",
- to_string=True)
-
# This logical structure closely follows the original code (which is clearer
# in C++). Keep them parallel to make them easier to compare.
if libcpp_abi_alternate_string_layout:
- if libcpp_big_endian:
+ if _libcpp_big_endian:
return short_size >> 1
else:
return short_size
- elif libcpp_big_endian:
+ elif _libcpp_big_endian:
return short_size
else:
return short_size >> 1
@@ -969,6 +965,14 @@
# certain pathological cases. Limit our pretty printers to the progspace.
def _register_libcxx_printers(event):
progspace = event.new_objfile.progspace
+ # It would be ideal to get the endianness at print time, but
+ # gdb.execute clears gdb's internal wrap buffer, removing any values
+ # already generated as part of a larger data structure, and there is
+ # no python api to get the endianness. Mixed-endianness debugging
+ # rare enough that this workaround should be adequate.
+ _libcpp_big_endian = "big endian" in gdb.execute("show endian",
+ to_string=True)
+
if not getattr(progspace, _libcxx_printer_name, False):
print("Loading libc++ pretty-printers.")
gdb.printing.register_pretty_printer(
