On 9/28/26 1:05 AM, Tamar Christina wrote:
LTO bootstrap currently fails due to MPFR and GMP failing stage2 vs stage3
comparison:
mpfr/src/urandom.o differs
mpfr/src/urandomb.o differs
mpfr/src/vasprintf.o differs
mpfr/src/yn.o differs
mpfr/src/zeta.o differs
mpfr/src/zeta_ui.o differs
of pretty much every object file for mpfr and mpc.
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 due to the
headers ending up with the checking flags inside them.
stage2-gmp/gmp.h:2334 #define __GMP_CC " ... -fno-checking"
stage3-gmp/gmp.h:2334 #define __GMP_CC " ... -fchecking=1"
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.
Since MPFR and GMP are C programs just prevent -fno-checking and -fchecking=1
from getting passed to them.
This patch adds a little autogen macro and Scheme function to strip out these
flags only for mpfr and gmp.
Bootstrapped Regtested on aarch64-none-linux-gnu,
arm-none-linux-gnueabihf, x86_64-pc-linux-gnu
-m32, -m64
with:
- default bootstrap
- profiledbootstrap
- LTO bootstrap
- LTO+O3
- bootstrap lto locality
- boostrap LTO lean
Ok for master?
Thanks,
Tamar
ChangeLog:
PR bootstrap/127376
* Makefile.in: Renegerate.
* Makefile.tpl: Strip checking flags for mpfr and gmp.
Seems sensible. So if it's working, it's OK for the trunk.
jeff
