[Bug bootstrap/91034] In tree build of gmp fails on Raspberry Pi4 (ARM Cortex A72) with `mls r1,r4,r8,r11' not supported in ARM mode

andrewm.roberts at sky dot com gcc-bugzilla@gcc.gnu.org
Mon Jul 1 16:48:00 GMT 2019


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91034

--- Comment #11 from Andrew Roberts <andrewm.roberts at sky dot com> ---
Richard,
the cpu supports mls (its a ARM Cortex A72). 

Comment 2 shows the -v output for both building gmp within gcc and standalone.
When building gmp in tree using Raspbian compiler:

as --gdwarf2 -v -I . -I ../../../gcc-9.1.0/gmp/mpn -I .. -I
../../../gcc-9.1.0/gmp -march=armv6 -mfloat-abi=hard -mfpu=vfp -meabi=5
--noexecstack -o divrem_1.o tmp-divrem_1.s

The issue is that when building gmp in tree no assembler code is supposed to be
used.

This looks like a problem with the Raspbian build of gcc breaking something. 
Possibly relating to CFLAGS, as setting CFLAGS to -v also causes the standalone
build of gmp to break with similar assembler errors.

When building an original gcc-8.3.0 or 9.1.0 release using the system gmp (not
in tree), this compiler can then be used to rebuild its self with gmp in tree
with no issues. So problem is specific to the Raspbian host compiler.


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