https://bugs.kde.org/show_bug.cgi?id=369053
Bug ID: 369053
Summary: AMD64 fma4 instructions missing 256 bit support
Product: valgrind
Version: 3.9.0
Platform: Other
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: vex
Assignee: jsew...@acm.org
Reporter: m...@redhat.com
CC: andreas.boer...@w84u.org, bellamy.b...@gmail.com,
dra...@shaw.ca, m...@redhat.com, p4pl...@gmail.com,
smj...@gmail.com, t...@compton.nu
Depends on: 369000
Blocks: 339596
Lets clone this once again. We now have fma4 support, but only for the
128bit/xmm cases. There are already tests (in none/tests/amd64/fma4.c) for the
256bit/ymm cases, but these are disabled for now because those aren't
implemented yet. This would need to check getVexL(pfx) and extend the
operations to the full 256bits.
+++ This bug was initially created as a clone of Bug #369000 +++
Lets split the fma4 and xop instructions into separate bugs & patches.
(I have already looked at the fma4 ones, but haven't had time for the xop
instructions.)
+++ This bug was initially created as a clone of Bug #339596 +++
When running valgrind upon program startup I immediately run into an illegal
instruction. My first action was to try using the latest source from SVN, this
however, did not help. Below are a few extra details on the instruction in
question, my system, and anything else I can think of.
vex amd64->IR: unhandled instruction bytes: 0x8F 0xE8 0x78 0xCD 0xC1 0x4 0xC5
0xF9
vex amd64->IR: REX=0 REX.W=0 REX.R=0 REX.X=0 REX.B=0
vex amd64->IR: VEX=0 VEX.L=0 VEX.nVVVV=0x0 ESC=NONE
vex amd64->IR: PFX.66=0 PFX.F2=0 PFX.F3=0
==16432== valgrind: Unrecognised instruction at address 0x5adb623.
==16432== at 0x5ADB623: findChar(QChar const*, int, QChar, int,
Qt::CaseSensitivity) (in /usr/lib64/libQt5Core.so.5.4.0)
==16432== by 0x5AEC0C9: QString::split(QChar, QString::SplitBehavior,
Qt::CaseSensitivity) const (in /usr/lib64/libQt5Core.so.5.4.0)
==16432== by 0x5BC8E61:
QStandardPaths::standardLocations(QStandardPaths::StandardLocation) (in
/usr/lib64/libQt5Core.so.5.4.0)
==16432== by 0x5B7D9B7:
QStandardPaths::locate(QStandardPaths::StandardLocation, QString const&,
QFlags<QStandardPaths::LocateOption>) (in /usr/lib64/libQt5Core.so.5.4.0)
==16432== by 0x5BB6028: QLoggingRegistry::init() (in
/usr/lib64/libQt5Core.so.5.4.0)
==16432== by 0x5C2BC8A: QCoreApplication::init() (in
/usr/lib64/libQt5Core.so.5.4.0)
==16432== by 0x5C2BEF5:
QCoreApplication::QCoreApplication(QCoreApplicationPrivate&) (in
/usr/lib64/libQt5Core.so.5.4.0)
==16432== by 0x5560718:
QGuiApplication::QGuiApplication(QGuiApplicationPrivate&) (in
/usr/lib64/libQt5Gui.so.5.4.0)
==16432== by 0x4F8F23C: QApplication::QApplication(int&, char**, int) (in
/usr/lib64/libQt5Widgets.so.5.4.0)
==16432== by 0x40D62D: main (main.cpp:37)
I've run it through GDB and grabbed a disassembly output (More can be provided
if requested):
0x0000000005adb619 <+329>: mov %r8,%rax
0x0000000005adb61c <+332>: vmovups (%rax),%xmm0
0x0000000005adb620 <+336>: mov %rcx,%r8
=> 0x0000000005adb623 <+339>: vpcomw $0x4,%xmm1,%xmm0,%xmm0
0x0000000005adb629 <+345>: vpmovmskb %xmm0,%esi
0x0000000005adb62d <+349>: test %si,%si
0x0000000005adb630 <+352>: je 0x5adb610
<_ZL8findCharPK5QChariS_iN2Qt15CaseSensitivityE+320>
0x0000000005adb632 <+354>: bsf %esi,%esi
0x0000000005adb635 <+357>: sub %rdi,%rax
My system CPU is an AMD FX-8150, and Qt (where the instruction seems to
originate) is compiled with GCC 4.8. I am running a Gentoo based system and
have used -march=native, -O2, and -fomit-frame-pointer as my only three default
CFLAGS.
If it helps I can setup a VM with SSH access temporarily to aid in
testing/debugging of the problem. However, for sanity sake I will only do this
Valgrind developers.
My final observersations seem to be that the XOP and FM4 instructions
introduced in the bulldozer generation AMD processors seem to cause the most
trouble. But that may be beyond the scope of this bug report.
Reproducible: Always
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