Bug 727656 - assembler_x86 emits REX.W prefix for instructions that don't support it
Summary: assembler_x86 emits REX.W prefix for instructions that don't support it
Alias: None
Product: Fedora
Classification: Fedora
Component: java-1.6.0-openjdk
Version: 15
Hardware: Unspecified
OS: Linux
Target Milestone: ---
Assignee: Deepak Bhole
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2011-08-02 18:44 UTC by Andreas Girgensohn
Modified: 2012-08-07 15:56 UTC (History)
8 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2012-08-07 15:56:34 UTC

Attachments (Terms of Use)

Description Andreas Girgensohn 2011-08-02 18:44:38 UTC
Description of problem:

Bug 720854 uncovered a problem where valgrind did not handle a PTEST instruction with the REX.W prefix.  According to Jakub Jelinek and the Intel 64 and IA-32 Architectures Software Developer’s Manual (http://www.intel.com/Assets/PDF/manual/325383.pdf), that instruction does not support that prefix.

I went through hotspot/src/cpu/x86/vm/assembler_x86.cpp and checked instructions against the Instruction Set Reference.  The following instructions do not list REX.W as an option (with page numbers of the reference).

MOVDQA (p. 3-671)
MOVDQU (p. 3-674)
PCMPESTRI (p. 4-85)
PSRLQ (p. 4-244)
PTEST (p. 4-262)

The corresponding methods should probably call prefix_and_encode instead of prefixq_and_encode.

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. Launch tomcat6 from valgrind (see options below)

Actual results:

valgrind raises a SIGILL signal

Expected results:

valgrind and tomcat would run

Additional info:

In /usr/sbin/tomcat6:

JAVACMD="/usr/bin/valgrind --smc-check=all --trace-children=yes
--log-file=/var/log/tomcat6/valgrind.out --leak-check=yes --tool=memcheck

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