my kernel does not boot anymore on a ppc970 (powermac g5) due to an illegal
instruction caused by gcc 4.5
research showed that the DI bswap64 operation is optimized to ldbrx even on
power4, but causes an sigill there.
gcc -m64 -c -O2 -mcpu=power4 -mtune=cell
gcc/testsuite/gcc.target/powerpc/optimize-bswapdi-3.c ; objdump -d
optimize-bswapdi-3.o
0000000000000000 <.swap64_load>:
0: 7c 00 1c 28 .long 0x7c001c28
4: 7c 03 03 78 mr r3,r0
8: 4e 80 00 20 blr
while:
gcc -m64 -c -O2 -mcpu=power4
gcc/testsuite/gcc.target/powerpc/optimize-bswapdi-3.c ; objdump -d
optimize-bswapdi-3.o
0000000000000000 <.swap64_load>:
0: 39 20 00 04 li r9,4
4: 7c 00 1c 2c lwbrx r0,0,r3
8: 7d 69 1c 2c lwbrx r11,r9,r3
c: 79 6a 07 c6 rldicr r10,r11,32,31
10: 7d 4a 03 78 or r10,r10,r0
14: 7d 43 53 78 mr r3,r10
18: 4e 80 00 20 blr
-mcpu=power4 -mtune=cell should not start to emit opcodes invalid on power4.
I think the bswap64 emitter logic in config/rs6000/rs6000.md is incorrect
--
Summary: -mcpu=power4 -mtune=cell emits power7/cell-only opcodes
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: marcus at jet dot franken dot de
GCC build triplet: powerpc-unknown-linux-gnu
GCC host triplet: powerpc-unknown-linux-gnu
GCC target triplet: powerpc-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43871
