Hello,
Jeff Law <jeffreya...@gmail.com> writes:
> On 6/19/23 22:52, Tamar Christina wrote:
>
>>> It's a bit hackish, but could we reject the stack pointer for operand1 in
>>> the
>>> stack-tie? And if we do so, does it help?
>> Yeah this one I had to defer until later this week to look at closer because
>> what I'm
>> wondering about is whether the optimization should apply to frame related
>> RTX as well.
>> Looking at the description of RTX_FRAME_RELATED_P that this optimization may
>> end up de-optimizing RISC targets by creating an offset that is larger than
>> offset
>> which can be used from a SP making reload having to spill. i.e. sometimes
>> the
>> move was explicitly done. So perhaps it should not apply it to
>> RTX_FRAME_RELATED_P in find_oldest_value_reg and copyprop_hardreg_forward_1?
>> Other parts of this pass already seems to bail out in similar situations. So
>> I needed
>> to
>> write some testcases to check what would happen in these cases hence the
>> deferral.
>> to later in the week.
> Rejecting for RTX_FRAME_RELATED_P would seem reasonable and probably better
> in general to
> me. The cases where we're looking to clean things up aren't really in the
> prologue/epilogue, but instead in the main body after register elimination
> has turned fp
> into sp + offset, thus making all kinds of things no longer valid.
The problems I reported were fixed by commits:
580b74a79146 "aarch64: Robustify stack tie handling"
079f31c55318 "aarch64: Fix gcc.target/aarch64/sve/pcs failures"
Thanks!
But unfortunately I'm still seeing bootstrap failures (ICE segmentation
fault) in today's trunk with build config bootstrap-lto in both
armv8l-linux-gnueabihf and aarch64-linux-gnu.
If I revert commit 6a2e8dcbbd4b "cprop_hardreg: Enable propagation of
the stack pointer if possible" from trunk then both bootstraps succeed.
Here's the command I'm using to build on armv8l:
~/src/configure \
SHELL=/bin/bash \
--with-gnu-as \
--with-gnu-ld \
--disable-libmudflap \
--enable-lto \
--enable-shared \
--without-included-gettext \
--enable-nls \
--with-system-zlib \
--disable-sjlj-exceptions \
--enable-gnu-unique-object \
--enable-linker-build-id \
--disable-libstdcxx-pch \
--enable-c99 \
--enable-clocale=gnu \
--enable-libstdcxx-debug \
--enable-long-long \
--with-cloog=no \
--with-ppl=no \
--with-isl=no \
--disable-multilib \
--with-float=hard \
--with-fpu=neon-fp-armv8 \
--with-mode=thumb \
--with-arch=armv8-a \
--enable-threads=posix \
--enable-multiarch \
--enable-libstdcxx-time=yes \
--enable-gnu-indirect-function \
--disable-werror \
--enable-checking=yes \
--enable-bootstrap \
--with-build-config=bootstrap-lto \
--enable-languages=c,c++,fortran,lto \
&& make \
profiledbootstrap \
SHELL=/bin/bash \
-w \
-j 40 \
CFLAGS_FOR_BUILD="-pipe -g -O2" \
CXXFLAGS_FOR_BUILD="-pipe -g -O2" \
LDFLAGS_FOR_BUILD="-static-libgcc" \
MAKEINFOFLAGS=--force \
BUILD_INFO="" \
MAKEINFO=echo
And here's the slightly different one for aarch64-linux:
~/src/configure \
SHELL=/bin/bash \
--with-gnu-as \
--with-gnu-ld \
--disable-libmudflap \
--enable-lto \
--enable-shared \
--without-included-gettext \
--enable-nls \
--with-system-zlib \
--disable-sjlj-exceptions \
--enable-gnu-unique-object \
--enable-linker-build-id \
--disable-libstdcxx-pch \
--enable-c99 \
--enable-clocale=gnu \
--enable-libstdcxx-debug \
--enable-long-long \
--with-cloog=no \
--with-ppl=no \
--with-isl=no \
--disable-multilib \
--enable-fix-cortex-a53-835769 \
--enable-fix-cortex-a53-843419 \
--with-arch=armv8-a \
--enable-threads=posix \
--enable-multiarch \
--enable-libstdcxx-time=yes \
--enable-gnu-indirect-function \
--disable-werror \
--enable-checking=yes \
--enable-bootstrap \
--with-build-config=bootstrap-lto \
--enable-languages=c,c++,fortran,lto \
&& make \
profiledbootstrap \
SHELL=/bin/bash \
-w \
-j 40 \
LDFLAGS_FOR_TARGET="-Wl,-fix-cortex-a53-843419" \
CFLAGS_FOR_BUILD="-pipe -g -O2" \
CXXFLAGS_FOR_BUILD="-pipe -g -O2" \
LDFLAGS_FOR_BUILD="-static-libgcc" \
MAKEINFOFLAGS=--force \
BUILD_INFO="" \
MAKEINFO=echo
--
Thiago
