[llvm] r335561 - [gdb] Escape unprintable bytes in SmallString and StringRef

[David Blaikie via llvm-commits]

Hey Ray - do you recall what the motivation for this patch was/is? I ask
because this breaks gdb's ability to truncate long strings (which means
printing out data structures with StringRefs that refer to, for instance,
the entire contents of an object/executable, or of a section in such a file
- is unfortunate/locks up the debugger for ages printing things out) and it
looks like gdb escapes unprintable characters itself, without the need to
do this manually so far as I can tell?

On Mon, Jun 25, 2018 at 5:46 PM Fangrui Song via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: maskray
> Date: Mon Jun 25 17:41:49 2018
> New Revision: 335561
>
> URL: http://llvm.org/viewvc/llvm-project?rev=335561&view=rev
> Log:
> [gdb] Escape unprintable bytes in SmallString and StringRef
>
> Modified:
>     llvm/trunk/utils/gdb-scripts/prettyprinters.py
>
> Modified: llvm/trunk/utils/gdb-scripts/prettyprinters.py
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/gdb-scripts/prettyprinters.py?rev=335561&r1=335560&r2=335561&view=diff
>
> ==============================================================================
> --- llvm/trunk/utils/gdb-scripts/prettyprinters.py (original)
> +++ llvm/trunk/utils/gdb-scripts/prettyprinters.py Mon Jun 25 17:41:49 2018
> @@ -11,6 +11,8 @@ class Iterator:
>    def children(self):
>      return self
>
> +def escape_bytes(val, l):
> +  return '"' + val.string(encoding='Latin-1',
> length=l).encode('unicode_escape').decode() + '"'
>
>  class SmallStringPrinter:
>    """Print an llvm::SmallString object."""
> @@ -21,10 +23,7 @@ class SmallStringPrinter:
>    def to_string(self):
>      begin = self.val['BeginX']
>      end = self.val['EndX']
> -    return begin.cast(gdb.lookup_type("char").pointer()).string(length =
> end - begin)
> -
> -  def display_hint (self):
> -    return 'string'
> +    return escape_bytes(begin.cast(gdb.lookup_type('char').pointer()),
> end - begin)
>
>  class StringRefPrinter:
>    """Print an llvm::StringRef object."""
> @@ -33,10 +32,7 @@ class StringRefPrinter:
>      self.val = val
>
>    def to_string(self):
> -    return self.val['Data'].string(encoding='Latin-1',
> length=self.val['Length'])
> -
> -  def display_hint (self):
> -    return 'string'
> +    return escape_bytes(self.val['Data'], self.val['Length'])
>
>  class SmallVectorPrinter:
>    """Print an llvm::SmallVector object."""
>
>
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