On 11/11/26 3:15 PM, Matt Turner wrote:
Alpha is one of the last targets still forcing TARGET_LRA_P to false, and
reload is slated for removal (PR113932). Add a transitional -mlra option,
following the hppa pattern (r16-5534), so that -mno-lra remains available as
an escape hatch until reload is deleted.
LRA is enabled by default only on BWX targets. On non-BWX targets a QImode or
HImode pseudo that has to be spilled reaches the target's reload_in<mode> /
reload_out<mode> secondary-reload path, which LRA does not yet drive correctly
(PR117185: LRA either loops generating reload insns or passes a pseudo where
get_unaligned_address expects a MEM). BWX has real byte/word memory
instructions and does not need that path, so it is unaffected. Gating the
default on TARGET_BWX enables LRA where it is known good and leaves non-BWX on
reload until PR117185 is resolved. -mlra / -mno-lra override the default in
either direction.
The default is resolved in alpha_option_override once TARGET_BWX is final, so
it tracks -mcpu (e.g. -mcpu=ev4 selects reload, -mcpu=ev56 selects LRA) rather
than only the configured default CPU.
Tested with an alpha-linux-gnu cross (both ev4/non-BWX and --with-cpu=ev56/BWX,
--enable-checking=yes,rtl): libgcc, libgomp and libstdc++ build cleanly under
LRA, and gcc.c-torture/execute under qemu-alpha at -O0 and -O2 gives identical
results with -mlra and -mno-lra on both configurations (3380 results each, no
differences). A native ev56 bootstrap with c,c++,m2 completes and, comparing a
full make check-gcc/check-g++ at the default (LRA) against --target_board
unix/-mno-lra (reload), LRA shows no correctness regressions: gcc unexpected
failures drop from 626 to 541 and g++ from 57 to 56, with the only LRA-only
differences being debug-info-quality (gcc.dg/guality) shifts in LRA's favor.
The prerequisite middle-end fix for the BWX m2 miscompile is PR117184.
gcc/ChangeLog:
* config/alpha/alpha.opt (mlra): New option.
* config/alpha/alpha.opt.urls: Regenerate.
* config/alpha/alpha.cc (alpha_option_override): Default alpha_lra_p
to TARGET_BWX when not set explicitly.
(alpha_use_lra_p): New function.
(TARGET_LRA_P): Define to it instead of hook_bool_void_false.
OK
jeff
