http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47977
Summary: powerpc (-mcpu=8548) Wrong code for double operations in little endian mode Product: gcc Version: 4.5.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassig...@gcc.gnu.org ReportedBy: m.lazzaro...@robox.it * Output of gcc -v : COLLECT_GCC=~/gcc-powerpc-4.5.2/bin/powerpc-eabi-gcc COLLECT_LTO_WRAPPER=~/gcc-powerpc-4.5.2/libexec/gcc/powerpc-eabi/4.5.2/lto-wrapper Target: powerpc-eabi Configured with: ~/build-gcc-4.5/src/gcc-4.5.2/configure --prefix ~/gcc-powerpc-4.5.2 --with-local-prefix=~/gcc-powerpc-4.5.2 --enable-languages=c,c++ --target=powerpc-eabi --disable-threads --disable-tls --disable-libmudflap --disable-libssp --disable-libgomp --with-gnu-ld --enable-e500-double Thread model: single gcc version 4.5.2 (GCC) * The program that triggers the bug : [test_fp.c] double test_fp(double val) { return val + val; } * Command line for big-endian : ~/gcc-powerpc-4.5.2/bin/powerpc-eabi-gcc-4.5.2 -c -mhard-float -fomit-frame-pointer -fno-exceptions -Wall -Werror -fpack-struct=8 -G8 -mcpu=8548 -misel=yes -meabi -O2 -mno-strict-align -mno-multiple -Wno-strict-aliasing -msdata=none -S -mbig test_fp.c -o test_fp-be.s * Command line for little-endian : ~/gcc-powerpc-4.5.2/bin/powerpc-eabi-gcc-4.5.2 -c -mhard-float -fomit-frame-pointer -fno-exceptions -Wall -Werror -fpack-struct=8 -G8 -mcpu=8548 -misel=yes -meabi -O2 -mno-strict-align -mno-multiple -Wno-strict-aliasing -msdata=none -S -mlittle test_fp.c -o test_fp-le.s * * * The output files, with comments: $ cat test_fp-be-COMMMENTED.s .file "test_fp.c" .gnu_attribute 4, 2 .gnu_attribute 8, 1 .gnu_attribute 12, 1 .section ".text" .align 2 .globl test_fp .type test_fp, @function test_fp: stwu 1,-16(1) efdadd 3,3,3 # val = val + val lwz 9,8(1) # What's the purpose ? lwz 10,12(1) # What's the purpose ? evmergehi 9,3,3 # R9 = HIGH DWORD (correct in big endian mode) mr 10,3 # R10 = LOW DWORD (correct in big endian mode) stw 9,8(1) # What's the purpose ? mr 3,9 # R3 = R9, HIGH dword correct (big endian) stw 10,12(1) # What's the purpose ? mr 4,10 # R4 = R10, LOW dword correct (big endian) addi 1,1,16 blr # remarque: is there a way to exit with a 64 bit register (f.i. R3) ? .size test_fp, .-test_fp .ident "GCC: (GNU) 4.5.2" $ cat test_fp-le-COMMENTED.s .file "test_fp.c" .gnu_attribute 4, 2 .gnu_attribute 8, 1 .gnu_attribute 12, 1 .section ".text" .align 2 .globl test_fp .type test_fp, @function test_fp: stwu 1,-16(1) efdadd 3,3,3 # val = val + val lwz 9,8(1) # What's the purpose ? lwz 10,12(1) # What's the purpose ? evmergehi 9,3,3 # R9 = HIGH DWORD (error in little endian mode???) mr 10,3 # R10 = LOW DWORD (error in little endian mode???) stw 9,8(1) # What's the purpose ? mr 3,9 # R3 = R9, LOW dword expected (little endian) but R9 is HIGH dword!!!! stw 10,12(1) # What's the purpose ? mr 4,10 # R4 = R10, HIGH dword expected (little endian) but R10 is LOW dword!!! addi 1,1,16 blr # remarque: is there a way to exit with a 64 bit register (f.i. R3) ? .size test_fp, .-test_fp .ident "GCC: (GNU) 4.5.2"