aarch64: Fix DWARF frame register sizes for predicates
Jakub pointed out that __builtin_init_dwarf_reg_size_table
set the size of predicate registers to their current runtime
size when compiled with +sve, but to 8 bytes otherwise.
As explained in the comment, both behaviours are wrong.
Predicates change size with VL and should never need to be
restored during unwinding.
In contrast, the call-saved FP&SIMD frame registers are 8 bytes
(even though the hardware registers are at least 16 bytes) and
the call-clobbered registers have zero size. A zero size seems
correct for predicates too.
gcc/
* config/aarch64/aarch64.cc (aarch64_dwarf_frame_reg_mode): New
function.
(TARGET_DWARF_FRAME_REG_MODE): Define.
gcc/testsuite/
* gcc.target/aarch64/dwarf_reg_size_1.c: New test.
* gcc.target/aarch64/dwarf_reg_size_2.c: Likewise.