Comment #19 on issue 615 by [email protected]: "instanceof" operator broken
on x64
http://code.google.com/p/v8/issues/detail?id=615
It seems impossible for the source code to produce the generated code
shown, unless
there is a compiler bug. So I would like to look at the code that
generates the
InstanceofStub stub. Could I get a copy of the disassembly of
InstanceofStub::Generate? I am especially interested in the lines around
address
300, calling the CmpObjectType function. The disassembly I got has the line
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+287>: mov
0x318103(%rip),%ecx # 0x81e808 <_ZN2v88internal16kScratchRegisterE>
which loads the correct register, r10, rather than the rax.
You would do this by entering gdb, with the command
gdb shell
and typing:
(gdb)
disass 'v8::internal::InstanceofStub::Generate(v8::internal::MacroAssembler*)'
Here is what I got, and the lines at addresses 287 through 300 generate the
code that
is different on your two builds.
Dump of assembler code for function
_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE:
0x00000000005065e0
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+0>:
push %r15
0x00000000005065e2
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+2>: mov
$0x10,%edx
0x00000000005065e7
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+7>:
push %r14
0x00000000005065e9
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+9>:
push %r13
0x00000000005065eb
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+11>:
push %r12
...
0x00000000005066f4
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+276>: mov
%r13,%rdx
0x00000000005066f7
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+279>: mov
%rbx,%rdi
0x00000000005066fa
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+282>: callq
0x529e80
<_ZN2v88internal14MacroAssembler9JumpIfSmiENS0_8RegisterEPNS0_5LabelE>
0x00000000005066ff
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+287>: mov
0x318103(%rip),%ecx # 0x81e808 <_ZN2v88internal16kScratchRegisterE>
---Type <return> to continue, or q <return> to quit---
0x0000000000506705
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+293>: mov
0x303f0d(%rip),%esi # 0x80a618 <_ZN2v88internal3rbxE>
0x000000000050670b
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+299>: mov
$0x9d,%edx
0x0000000000506710
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+304>: mov
%rbx,%rdi
0x0000000000506713
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+307>: callq
0x52a960
<_ZN2v88internal14MacroAssembler13CmpObjectTypeENS0_8RegisterENS0_12InstanceTypeES2_>
0x0000000000506718
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+312>: mov
%r13,%rdx
0x000000000050671b
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+315>: mov
$0x2,%esi
0x0000000000506720
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+320>: mov
%rbx,%rdi
0x0000000000506723
<_ZN2v88internal14InstanceofStub8GenerateEPNS0_14MacroAssemblerE+323>: callq
0x4f5fb0 <_ZN2v88internal9Assembler1jENS0_9ConditionEPNS0_5LabelE>
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