[Buildroot] [PATCH 1/1] qt: fix build on powerpc_e500mc

Peter Korsgaard peter at korsgaard.com
Sat Sep 1 21:30:45 UTC 2018


>>>>> "Fabrice" == Fabrice Fontaine <fontaine.fabrice at gmail.com> writes:

 > gcc bug internal compiler error: in validate_condition_mode, at
 > config/rs6000/rs6000.c:180744. Bug is fixed since gcc 7.2.
 > Workaround is to set -mno-isel, see
 > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60818 and
 > https://gcc.gnu.org/ml/gcc-patches/2016-02/msg01036.html

 > Fixes:
 >  - http://autobuild.buildroot.net/results/9b9d11b3281a72c8f54fc675408acb96d24d8e7e

 > Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
 > ---
 >  package/qt/qt.mk | 9 +++++++++
 >  1 file changed, 9 insertions(+)

 > diff --git a/package/qt/qt.mk b/package/qt/qt.mk
 > index 1dcb05d6af..24ebbfdfdb 100644
 > --- a/package/qt/qt.mk
 > +++ b/package/qt/qt.mk
 > @@ -32,6 +32,15 @@ QT_LDFLAGS = $(TARGET_LDFLAGS)
 >  # use an older c++ standard to prevent build failure
 >  QT_CXXFLAGS += -std=gnu++98
 
 > +# gcc bug internal compiler error: in validate_condition_mode, at
 > +# config/rs6000/rs6000.c:180744. Bug is fixed since gcc 7.2.
 > +# Workaround is to set -mno-isel, see
 > +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60818 and
 > +# https://gcc.gnu.org/ml/gcc-patches/2016-02/msg01036.html
 > +ifeq ($(BR2_powerpc_e500mc):$(BR2_TOOLCHAIN_GCC_AT_LEAST_8),y:)

If it is fixed in 7.2.0, why are we then using the workaround for 7.x as
well? Is this for external toolchains using 7.{0..1}.x? 7.2.0 was
released more than 1 year ago.

What is the impact of using -mno-isel? Performance? From googling, it
looks like a conditional move instruction:

https://www.rapitasystems.com/blog/interesting-microcontroller-features-powerpc-isel-instruction

-- 
Bye, Peter Korsgaard


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