https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127376
Bug ID: 127376
Summary: boostrap-lto fails with a compare error
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: bootstrap
Assignee: unassigned at gcc dot gnu.org
Reporter: tnfchris at gcc dot gnu.org
Target Milestone: ---
On
- aarch64-none-linux-gnu
- arm-none-linux-gnueabihf
- x86_64-pc-linux-gnu
configured with --enable-checking=yes,rtl,extra
--with-build-config=bootstrap-lto
always ends in stage2 vs stage3 comparison failures
15:36:29 mpfr/src/urandom.o differs
15:36:29 mpfr/src/urandomb.o differs
15:36:29 mpfr/src/vasprintf.o differs
15:36:29 mpfr/src/yn.o differs
15:36:29 mpfr/src/zeta.o differs
15:36:29 mpfr/src/zeta_ui.o differs
of pretty much every object file.
This is because in Makefile.tpl +579 we have
STAGE1_TFLAGS += -fno-checking
STAGE2_CFLAGS += -fno-checking
STAGE2_TFLAGS += -fno-checking
STAGE3_CFLAGS += -fchecking=1
STAGE3_TFLAGS += -fchecking=1
But with a LTO bootstrap the options leak into the LTO metadata.
during an LTO bootstrap we call compare-lto which strips the options from
.gnu.lto_.opts but they're also present in .gnu.lto_.decls.*.
So we get a miscompare due to -fchecking differences.
I guess stripping options could be dangerous for .gnu.lto_.decls.*, so not sure
what the correct fix is here. one option is to force LTO bootstraps to have a
non-checking stage3? or a checked stage1 and 2?
