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Diffstat (limited to 'results/classifier/118/all/1701835')
| -rw-r--r-- | results/classifier/118/all/1701835 | 297 |
1 files changed, 297 insertions, 0 deletions
diff --git a/results/classifier/118/all/1701835 b/results/classifier/118/all/1701835 new file mode 100644 index 000000000..4fdbd13b8 --- /dev/null +++ b/results/classifier/118/all/1701835 @@ -0,0 +1,297 @@ +graphic: 0.968 +permissions: 0.945 +architecture: 0.932 +debug: 0.931 +virtual: 0.923 +assembly: 0.918 +performance: 0.918 +register: 0.916 +socket: 0.916 +files: 0.910 +semantic: 0.909 +device: 0.908 +arm: 0.906 +boot: 0.898 +PID: 0.894 +hypervisor: 0.890 +user-level: 0.889 +risc-v: 0.888 +peripherals: 0.888 +kernel: 0.887 +ppc: 0.879 +vnc: 0.856 +KVM: 0.854 +TCG: 0.850 +network: 0.838 +VMM: 0.837 +mistranslation: 0.833 +x86: 0.794 +i386: 0.769 + +floating-point operation bugs in qemu-alpha + +When running the gnulib testsuite, I'm seeing test failures in the tests for libm functions + cbrt + cbrtf + ceil + ceilf + coshf + exp2 + exp2f + floor + floorf + fma + fmaf + fmal + frexp + frexpf + hypot + hypotf + hypotl + ilogb + ilogbf + isfinite + isinf + isnan + isnand + isnanf + ldexp + ldexpf + ldexpl + log1p + log1pf + log2 + log2f + logb + logbf + logbl + rint + rintf + rintl + signbit + sqrt + sqrtf + strtod +that I don't see when running the same (statically linked) executables in a VM, through qemu-system-alpha. + +How to reproduce: +- Using gnulib, run ./gnulib-tool --create-testdir --dir=../testdir-math --single-configure cbrt cbrtf ceil ceilf coshf exp2 exp2f float floor floorf fma fmaf fmal frexp frexpf hypot hypotf hypotl ilogb ilogbf isfinite isinf isnan isnand isnanf ldexp ldexpf ldexpl log1p log1pf log2 log2f logb logbf logbl math printf-frexp rint rintf rintl round roundf signbit sqrt sqrtf strtod trunc truncf +- Copy the resulting directory to a VM running Linux 2.6.26 with qemu-system-alpha. +- There, configure and build the package: + mkdir build-native-static; cd build-native-static; ../configure CPPFLAGS="-Wall" LDFLAGS="-static"; make; make check + Only 4 tests fail. +- Copy the resulting binaries back to the original x86_64 machine. +- Set environment variables for using qemu-alpha. +- Here, 50 tests fail that did not fail originally: + +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-cbrt +../../gltests/test-cbrt.h:39: assertion 'err > - L_(4.0) * L_(16.0) / TWO_MANT_DIG && err < L_(4.0) * L_(16.0) / TWO_MANT_DIG' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-ceil1 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-ceil2 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-ceilf1 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-ceilf2 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-coshf +../../gltests/test-coshf.c:37: assertion 'y >= 1.1854652f && y <= 1.1854653f' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-float +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-floor1 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-floor2 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-floorf1 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-floorf2 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-fma1 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-fma2 +../../gltests/test-fma2.h:116: assertion 'result == expected' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-fmaf1 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-fmaf2 +../../gltests/test-fma2.h:116: assertion 'result == expected' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-fmal2 +../../gltests/test-fma2.h:116: assertion 'result == expected' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-frexp +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-frexpf +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-hypot +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-hypotf +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-hypotl +../../gltests/test-hypot.h:41: assertion 'z == HUGEVAL' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-ilogb +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-ilogbf +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-isfinite +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-isinf +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-isnan +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-isnand-nolibm +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-isnand +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-isnanf-nolibm +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-isnanf +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-ldexp +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-ldexpf +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-ldexpl +../../gltests/test-ldexp.h:99: assertion 'y == expected' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-log1p +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-log1pf +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-log2 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-log2f +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-logb +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-logbf +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-math +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-printf-frexp +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-rint +../../gltests/test-rint.c:63: assertion 'rint (0.7) == 1.0' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-rintf +../../gltests/test-rintf.c:63: assertion 'rintf (0.7f) == 1.0f' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-rintl +../../gltests/test-rintl.c:68: assertion 'rintl (0.7L) == 1.0L' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-round1 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-roundf1 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-signbit +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-sqrt +../../gltests/test-sqrt.h:40: assertion 'err > - L_(16.0) / TWO_MANT_DIG && err < L_(16.0) / TWO_MANT_DIG' failed +Aborted (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-trunc1 +Floating point exception (core dumped) +$ ~/inst-qemu/2.9.0/bin/qemu-alpha test-truncf1 +Floating point exception (core dumped) + + + +The behaviour in qemu-2.11 is the same as in qemu-2.9. + +This is likely expected/correct behavior. You should try building with -mieee. + +> You should try building with -mieee. + +When I build with +../configure CFLAGS="-mieee -O2 -g" CPPFLAGS=-Wall LDFLAGS="-static -lieee" +I observe the exact same behaviour: Only 4 tests fail in a VM executed with qemu-system-alpha, whereas the same test failures (from test-cbrt to test-truncf1) are seen with qemu-alpha. + +Most likely some bits are initialized differently in the FPCR. + +Run this: + +#include <stdio.h> +#include <string.h> + +double get_fpcr() +{ + double x; + asm ("mf_fpcr %0": "=f" (x)); + return x; +} + +int main() +{ + double fpcr = get_fpcr(); + unsigned long l; + memcpy(&l, &fpcr, 8); + printf("%016lx\n", l); + return 0; +} + +Under qemu-system-alpha I get 680e800000000000. + +Under qemu-system-alpha I get 680e800000000000 as well. + +Under qemu-alpha (versions 2.8.1, 2.9.0, 2.10.0, 2.11.0, 2.12.0, 3.1.0) I get 600e800000000000, i.e. bit 59 is unset. + +https://download.majix.org/dec/alpha_arch_ref.pdf + +The bits are defined in 4.7.8 Floating-Point Control Register (FPCR). 59/58 zero is chopped rounding. This does not seem like a good default. + +The fpcr value seen in a process running in a VM comes from the Linux kernel, file linux/arch/alpha/kernel/process.c, function flush_thread(): + + /* Arrange for each exec'ed process to start off with a clean slate + with respect to the FPU. This is all exceptions disabled. */ + current_thread_info()->ieee_state = 0; + wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); + +where FPCR_DYN_NORMAL is 0x2UL << 58 /* towards nearest */ + +Where do we go from here? As far as I understand, qemu-alpha ought to initialize the DYN bits to FPCR_DYN_NORMAL. Where in the code should this be done? I see code in target/alpha/cpu.c, function alpha_cpu_initfn, that initializes the DYN bits to FPCR_DYN_NORMAL. Is this at the wrong place? Is it insufficient for another reason? + +Should be fixed by: + +http://lists.nongnu.org/archive/html/qemu-devel/2019-01/msg00726.html + +No, it is not fixed: even with this patch the program that fetches the fpcr still prints 600e800000000000, and the various program crashes still occur. + +Commit https://git.qemu.org/?p=qemu.git;a=commitdiff;h=29eb528078683 claims that this has been fixed. Is the problem still reproducible with QEMU 4.0? + +The problem is still reproducible with QEMU 4.0.0: +- The test programs test-cbrt ... test-truncf1 crash or abort as described. +- The test program from comment #6, run with qemu-alpha, prints 600e800000000000, i.e. bit 59 is unset. + +There seems to be more confusion of the sort. This fixes it for me: + +--- a/linux-user/syscall.c ++++ b/linux-user/syscall.c +@@ -10226,7 +10226,7 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1, + return -TARGET_EFAULT; + } + orig_fpcr = cpu_alpha_load_fpcr(cpu_env); +- fpcr = orig_fpcr & FPCR_DYN_MASK; ++ fpcr = orig_fpcr & ((uint64_t) FPCR_DYN_MASK << 32); + + /* Copied from linux ieee_swcr_to_fpcr. */ + fpcr |= (swcr & SWCR_STATUS_MASK) << 35; + +But I would consider this a workaround at best. Having a right-shifted mask in the first place seems rather unhelpful to me. + +There is quite a bit missing for proper user-level emulation. +Please try + +https://patchwork.ozlabs.org/patch/1091847/ + +The patch mentioned in #15 fixes the issue: +- The test programs test-cbrt ... test-truncf1 now all succeed. +- The test program from comment #6, run with qemu-alpha, prints 680e800000000000, i.e. bit 59 is set. + +Thanks Richard!! + +Patch now merged to master and will be in QEMU 4.1. + +https://git.qemu.org/?p=qemu.git;a=commitdiff;h=21ba856499f9c0ccdc + |