On Tue, Mar 09, 2021 at 10:05:04AM -0500, Andrew Cagney via Dwarf-Discuss wrote:
> Is anyone aware of a compiler doing this (I figure with LTO there's a
> strong incentive)? And if so, how is this described to the debugger.
> The ABI / calling-convention is no longer on hand for filling in the
> blanks.
Sure, GCC does that. On many architectures, IPA-RA might keep data
live across a function call even in registers that are per the ABI
officially call clobbered (if it can prove the particular callee does not
clobber it). This isn't expressed in DWARF I believe.
On x86, GCC can use different register calling conventions for local
functions (basically automatic regparm and/or sseregparm calling conventions
when possible). I think this is reflected in the debug info, the
DW_TAG_formal_parameter locations should match those.
Jakub
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