On 1/5/24 09:28, Richard Sandiford wrote:
function.cc emits a NOTE_FUNCTION_BEG after all arguments have
been copied to pseudos. It then records this note in parm_birth_insn.
Various other pieces of code use this insn as a convenient place to
insert things at the start of the function.
However, cfgexpand later changes parm_birth_insn as follows:
/* If we emitted any instructions for setting up the variables,
emit them before the FUNCTION_START note. */
if (var_seq)
{
emit_insn_before (var_seq, parm_birth_insn);
/* In expand_function_end we'll insert the alloca save/restore
before parm_birth_insn. We've just insertted an alloca call.
Adjust the pointer to match. */
parm_birth_insn = var_seq;
}
But the FUNCTION_BEG note is still useful for things that aren't
sensitive to stack allocation, and it has the advantage that
(unlike the var_seq above) it is never deleted or combined.
This patch adds a separate variable to track it.
Tested on aarch64-linux-gnu, where it's needed for fixing PR113196.
OK to install?
Richard
gcc/
* emit-rtl.h (rtl_data::x_function_beg_note): New member variable.
(function_beg_insn): New macro.
* function.cc (expand_function_start): Initialize function_beg_insn.
OK
jeff
