[LLVMbugs] [Bug 5116] New: x86-64 JIT omits stubs in some cases they're needed
bugzilla-daemon at cs.uiuc.edu
bugzilla-daemon at cs.uiuc.edu
Thu Oct 1 15:11:56 PDT 2009
http://llvm.org/bugs/show_bug.cgi?id=5116
Summary: x86-64 JIT omits stubs in some cases they're needed
Product: libraries
Version: trunk
Platform: PC
OS/Version: Linux
Status: NEW
Severity: normal
Priority: P2
Component: Backend: X86
AssignedTo: unassignedbugs at nondot.org
ReportedBy: jyasskin at google.com
CC: llvmbugs at cs.uiuc.edu
Created an attachment (id=3598)
--> (http://llvm.org/bugs/attachment.cgi?id=3598)
JITTest.cpp addition to provoke the bug
The attached unit test generates the following assembly:
0x00007ffff7f45010 <test+0>: sub $0x8,%rsp
0x00007ffff7f45014 <test+4>: mov $0x7,%edi
0x00007ffff7f45019 <test+9>: callq 0x800000427cd8
0x00007ffff7f4501e <test+14>: add $0x8,%rsp
0x00007ffff7f45022 <test+18>: retq
where the intended target function is actually at address 0x427cd8. This
appears to be happening because the actual 64-bit offset gets truncated to 32
bits when it's stored into the callq instruction. This will only happen on
x86-64 systems when JIT code is allocated into memory far away from the
pre-compiled code segment. If lazy compilation is enabled, or the function is
looked up via dlsym instead of addGlobalMapping, the error doesn't happen.
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