[llvm] r368339 - [MBP] Disable aggressive loop rotate in plain mode
Carrot Wei via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 15 16:00:09 PDT 2019
On Thu, Aug 15, 2019 at 8:10 AM Xinliang David Li <xinliangli at gmail.com> wrote:
>
> So your patch just triggered the bug? +David Blaikie.
>
It's very likely a debug information bug just triggered by the MBP
patch according to current finding. My understanding of the debug
information propagation should not depend on code layout, it depends
on data flow and control flow.
Before ExtendRanges processing bb62, the MBB looks like
bb.62 (%ir-block.187):
; predecessors: %bb.61
successors: %bb.63(0x80000000); %bb.63(100.00%)
liveins: $edi, $edx
renamable $eax = MOV32rm $esi, 1, $noreg, 0, $noreg :: (load 4 from %stack.54)
MOV32mr $esi, 1, $noreg, 24, $noreg, killed renamable $edx :: (store
4 into %stack.56)
renamable $edx = MOV32rm $esi, 1, $noreg, 20, $noreg :: (load 4 from
%stack.55)
renamable $eax = SHL32ri killed renamable $eax(tied-def 0), 2,
implicit-def dead $eflags, debug-location !13658;
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ..
/../v8/src/torque/csa-generator.cc:76 ] ]
renamable $ebx = LEA32r killed renamable $eax, 2, renamable $eax, 0,
$noreg, debug-location !13658; ../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/to
rque/csa-generator.cc:76 ] ]
renamable $eax = LEA32r $noreg, 4, killed renamable $edi, 0, $noreg,
debug-location !13658; ../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/torque/csa
-generator.cc:76 ] ]
renamable $eax = LEA32r killed renamable $eax, 2, renamable $eax, 0,
$noreg, debug-location !13658; ../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/to
rque/csa-generator.cc:76 ] ]
MOV32mr $esi, 1, $noreg, 0, $noreg, killed renamable $eax :: (store
4 into %stack.54)
Then it calls join to propagate the debug information from its
predecessors into bb62, bb62 has only 1 predecessor bb61
bb.61 (%ir-block.177):
; predecessors: %bb.60
successors: %bb.62(0x40000000), %bb.69(0x40000000); %bb.62(50.00%),
%bb.69(50.00%)
liveins: $eax, $ebx, $ecx, $edx
DBG_VALUE $ecx, $noreg, !"range", !DIExpression(DW_OP_LLVM_fragment,
0, 32), debug-location !13632; ../../v8\src/torque/utils.h:0 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/torq
ue/csa-generator.cc:76 ] ] line no:263
DBG_VALUE $eax, $noreg, !"i", !DIExpression(), debug-location
!13633; ../../v8\src/torque/utils.h:0 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ] lin
e no:266
DBG_VALUE $eax, $noreg, !"range", !DIExpression(DW_OP_LLVM_fragment,
32, 32), debug-location !13632; ../../v8\src/torque/utils.h:0 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/tor
que/csa-generator.cc:76 ] ] line no:263
DBG_VALUE $noreg, $noreg, !"this", !DIExpression(), debug-location
!13641; ../../v8\src/torque/utils.h:0 @[
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v
8/src/torque/csa-generator.cc:76 ] ] ] line no:0
DBG_VALUE $noreg, $noreg, !"this", !DIExpression(), debug-location
!13643; ../../v8\src/torque/utils.h:0 @[
../../v8\src/torque/utils.h:261 @[ ../../v8\src/torque/utils.h:266 @[
../../v8/src/to
rque/csa-generator.cc:94 @[ ../../v8/src/torque/csa-generator.cc:76 ]
] ] ] line no:0
DBG_VALUE $noreg, $noreg, !"this", !DIExpression(), debug-location
!13645; ../../buildtools/third_party/libc++/trunk/include\vector:0 @[
../../v8\src/torque/utils.h:224 @[ ../../v8\src/torque/u
tils.h:261 @[ ../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ] ] ] ] line no:0
MOV32mr $esi, 1, $noreg, 4, $noreg, killed renamable $eax :: (store
4 into %stack.53)
DBG_VALUE $esi, 0, !"range", !DIExpression(DW_OP_plus_uconst, 4,
DW_OP_LLVM_fragment, 32, 32), debug-location !13632;
../../v8\src/torque/utils.h:0 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ] line no:263 indirect
renamable $eax = MOV32rm renamable $ebx, 1, $noreg, 4, $noreg,
debug-location !13647 :: (load 4 from %ir.179);
../../buildtools/third_party/libc++/trunk/include\vector:656 @[
../../v8\src/torqu
e/utils.h:224 @[ ../../v8\src/torque/utils.h:261 @[
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ] ] ] ]
renamable $edi = MOV32rm renamable $ebx, 1, $noreg, 0, $noreg,
debug-location !13647 :: (load 4 from %ir.181);
../../buildtools/third_party/libc++/trunk/include\vector:656 @[
../../v8\src/torqu
e/utils.h:224 @[ ../../v8\src/torque/utils.h:261 @[
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ] ] ] ]
MOV32mr $esi, 1, $noreg, 0, $noreg, killed renamable $ecx :: (store
4 into %stack.54)
DBG_VALUE $esi, 0, !"range", !DIExpression(DW_OP_LLVM_fragment, 0,
32), debug-location !13632; ../../v8\src/torque/utils.h:0 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/torque/cs
a-generator.cc:76 ] ] line no:263 indirect
$ecx = MOV32rr $eax, debug-location !13647;
../../buildtools/third_party/libc++/trunk/include\vector:656 @[
../../v8\src/torque/utils.h:224 @[ ../../v8\src/torque/utils.h:261 @[
../../v8\src/to
rque/utils.h:266 @[ ../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ] ] ] ]
MOV32mr $esi, 1, $noreg, 20, $noreg, renamable $edi :: (store 4 into
%stack.55)
renamable $ecx = SUB32rr killed renamable $ecx(tied-def 0), killed
renamable $edi, implicit-def dead $eflags, debug-location !13647;
../../buildtools/third_party/libc++/trunk/include\vector:656
@[ ../../v8\src/torque/utils.h:224 @[ ../../v8\src/torque/utils.h:261
@[ ../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ]
] ] ]
renamable $edi = MOV32rm $esi, 1, $noreg, 4, $noreg :: (load 4 from %stack.53)
DBG_VALUE $edi, $noreg, !"range", !DIExpression(), debug-location
!13632; ../../v8\src/torque/utils.h:0 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ]
line no:263
renamable $ecx = exact SAR32ri killed renamable $ecx(tied-def 0), 2,
implicit-def dead $eflags, debug-location !13647;
../../buildtools/third_party/libc++/trunk/include\vector:656 @[
../../v8\s
rc/torque/utils.h:224 @[ ../../v8\src/torque/utils.h:261 @[
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ] ] ] ]
renamable $ecx = IMUL32rri killed renamable $ecx, -1431655765,
implicit-def dead $eflags, debug-location !13647;
../../buildtools/third_party/libc++/trunk/include\vector:656 @[
../../v8\src/tor
que/utils.h:224 @[ ../../v8\src/torque/utils.h:261 @[
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ] ] ] ]
DBG_VALUE $noreg, $noreg, !"this", !DIExpression(), debug-location
!13655; ../../v8\src/torque/utils.h:0 @[
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v
8/src/torque/csa-generator.cc:76 ] ] ] line no:0
DBG_VALUE $noreg, $noreg, !"other", !DIExpression(), debug-location
!13655; ../../v8\src/torque/utils.h:0 @[
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../
v8/src/torque/csa-generator.cc:76 ] ] ] line no:169
CMP32rr renamable $ecx, renamable $edi, implicit-def $eflags,
debug-location !13657; ../../v8\src/torque/utils.h:170 @[
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:9
4 @[ ../../v8/src/torque/csa-generator.cc:76 ] ] ]
JCC_1 %bb.69, 6, implicit $eflags, debug-location !13658;
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ]
This MBB has 5 DBG_VALUE instructions contains information about
variable "range". Function join adds 2 DBG_VALUE instructions about
variable "range" to bb62
bb.62 (%ir-block.187):
; predecessors: %bb.61
successors: %bb.63(0x80000000); %bb.63(100.00%)
liveins: $edi, $edx
DBG_VALUE $edi, $noreg, !"range", !DIExpression(), debug-location
!13632; ../../v8\src/torque/utils.h:0 @[
../../v8/src/torque/csa-generator.cc:94 @[
../../v8/src/torque/csa-generator.cc:76 ] ]
line no:263
DBG_VALUE $esi, 0, !"range", !DIExpression(DW_OP_LLVM_fragment, 0,
32), debug-location !13632; ../../v8\src/torque/utils.h:0 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/torque/cs
a-generator.cc:76 ] ] line no:263 indirect
renamable $eax = MOV32rm $esi, 1, $noreg, 0, $noreg :: (load 4 from %stack.54)
MOV32mr $esi, 1, $noreg, 24, $noreg, killed renamable $edx :: (store
4 into %stack.56)
renamable $edx = MOV32rm $esi, 1, $noreg, 20, $noreg :: (load 4 from
%stack.55)
renamable $eax = SHL32ri killed renamable $eax(tied-def 0), 2,
implicit-def dead $eflags, debug-location !13658;
../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ..
/../v8/src/torque/csa-generator.cc:76 ] ]
renamable $ebx = LEA32r killed renamable $eax, 2, renamable $eax, 0,
$noreg, debug-location !13658; ../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/to
rque/csa-generator.cc:76 ] ]
renamable $eax = LEA32r $noreg, 4, killed renamable $edi, 0, $noreg,
debug-location !13658; ../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/torque/csa
-generator.cc:76 ] ]
renamable $eax = LEA32r killed renamable $eax, 2, renamable $eax, 0,
$noreg, debug-location !13658; ../../v8\src/torque/utils.h:266 @[
../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/to
rque/csa-generator.cc:76 ] ]
MOV32mr $esi, 1, $noreg, 0, $noreg, killed renamable $eax :: (store
4 into %stack.54)
Then ExtendRanges process instructions in bb62 one by one.
1 the first DBG_VALUE instruction, a DebugVariable about var "range"
without fragment information is added to OpenRanges.
2 the second DBG_VALUE instruction, a DebugVariable about var "range"
with fragment information is added to OpenRanges.
3 the first MOV32rm instruction, the DebugVariable associated with the
second DBG_VALUE instruction is deleted from OpenRanges, a new
DebugVariable about var "range" without fragment information is added
to OpenRanges, the new DebugVariable is the same as the one associated
with the first DBG_VALUE instruction, but with a new ID, the new ID is
added to OpenRanges.VarLocs, OpenRanges.Vars is a map, so no new
DebugVariable is added to OpenRanges.Vars, it is just updated to map
to the new ID. So now OpenRanges.VarLocs and OpenRanges.Vars have
different number of elements.
Is there anything obviously wrong with these instructions and operations?
thanks
> David
>
> On Thu, Aug 15, 2019 at 12:02 AM Carrot Wei via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>>
>> When function LiveDebugValues::ExtendRanges works on following MBB
>>
>> bb.62 (%ir-block.187):
>> ; predecessors: %bb.61
>> successors: %bb.63(0x80000000); %bb.63(100.00%)
>> liveins: $edi, $edx
>> DBG_VALUE $edi, $noreg, !"range", !DIExpression(), debug-location !136
>> 32; ../../v8\src/torque/utils.h:0 @[
>> ../../v8/src/torque/csa-generator.cc:94 @[
>> ../../v8/src/torque/csa-generator.cc:76 ] ] line no:263
>> DBG_VALUE $esi, 0, !"range", !DIExpression(DW_OP_LLVM_fragment, 0, 32)
>> , debug-location !13632; ../../v8\src/torque/utils.h:0 @[ ../../v8/src/t
>> orque/csa-generator.cc:94 @[ ../../v8/src/torque/csa-generator.cc:76 ] ]
>> line no:263 indirect
>> renamable $eax = MOV32rm $esi, 1, $noreg, 0, $noreg :: (load 4 from %stack.54)
>> MOV32mr $esi, 1, $noreg, 24, $noreg, killed renamable $edx :: (store 4
>> into %stack.56)
>> renamable $edx = MOV32rm $esi, 1, $noreg, 20, $noreg :: (load 4 from %
>> stack.55)
>> renamable $eax = SHL32ri killed renamable $eax(tied-def 0), 2,
>> implicit-def dead $eflags, debug-location !13658;
>> ../../v8\src/torque/utils.h:2
>> 66 @[ ../../v8/src/torque/csa-generator.cc:94 @[ ../../v8/src/torque/csa
>> -generator.cc:76 ] ]
>> renamable $ebx = LEA32r killed renamable $eax, 2, renamable $eax, 0, $
>> noreg, debug-location !13658; ../../v8\src/torque/utils.h:266 @[ ../../v
>> 8/src/torque/csa-generator.cc:94 @[ ../../v8/src/torque/csa-generator.cc:76 ] ]
>> renamable $eax = LEA32r $noreg, 4, killed renamable $edi, 0, $noreg, d
>> ebug-location !13658; ../../v8\src/torque/utils.h:266 @[ ../../v8/src/to
>> rque/csa-generator.cc:94 @[ ../../v8/src/torque/csa-generator.cc:76 ] ]
>> renamable $eax = LEA32r killed renamable $eax, 2, renamable $eax, 0, $
>> noreg, debug-location !13658; ../../v8\src/torque/utils.h:266 @[
>> ../../v8/src/torque/csa-generator.cc:94 @[
>> ../../v8/src/torque/csa-generator.cc
>> :76 ] ]
>> MOV32mr $esi, 1, $noreg, 0, $noreg, killed renamable $eax :: (store 4
>> into %stack.54)
>>
>> The data structure OpenRanges got inconsistent internal state. Its
>> field OpenRanges.Vars and OpenRanges.VarLocs should have same number
>> of elements.
>>
>> Before handling the third instruction
>>
>> renamable $eax = MOV32rm $esi, 1, $noreg, 0, $noreg :: (load 4 from %stack.54)
>>
>> Both OpenRanges.Vars and OpenRanges.VarLocs have 2 elements. Then
>> function insertTransferDebugPair is called, it calls OpenRanges.erase
>> to delete 1 element from OpenRanges, then both OpenRanges.Vars and
>> OpenRanges.VarLocs have 1 element. Later OpenRanges.insert is called
>> for the new fragment, this function adds new element to
>> OpenRanges.Vars and OpenRanges.VarLocs at the same time, but the
>> SmallDenseMap OpenRanges.Vars already has the same key, so
>> OpenRanges.Vars just replaced the old value with new one, it still has
>> only 1 element, OpenRanges.VarLocs has 2 elements now. Later when
>> elements are removed from OpenRanges.Vars, OpenRanges.VarLocs still
>> contains 1 value, and caused the assertion failure in function
>> OpenRanges.empty.
>>
>> I'm not familiar with debug information, could anybody help to give me a hint?
>>
>> thanks a lot!
>>
>> On Tue, Aug 13, 2019 at 10:45 PM Carrot Wei <carrot at google.com> wrote:
>> >
>> > I didn't know llvm on linux can cross build windows binary.
>> > Now I can reproduce it.
>> >
>> > On Tue, Aug 13, 2019 at 12:21 AM Hans Wennborg <hans at chromium.org> wrote:
>> > >
>> > > Did you look at
>> > > https://bugs.chromium.org/p/chromium/issues/detail?id=992871#c3 ? It
>> > > shows how to reproduce using the tarball on Linux.
>> > >
>> > > On Mon, Aug 12, 2019 at 8:17 PM Carrot Wei <carrot at google.com> wrote:
>> > > >
>> > > > The MBP patch doesn't touch debug information, I suspect there is
>> > > > something unrelated was triggered.
>> > > > I tried your tarball, but found it is for windows, I don't have a
>> > > > windows machine :(. Do you have a linux reproduce? It's even better to
>> > > > have a compiler command line.
>> > > >
>> > > > On Mon, Aug 12, 2019 at 7:24 AM Hans Wennborg <hans at chromium.org> wrote:
>> > > > >
>> > > > > I've reverted this in r368579 since it causes asserts when building
>> > > > > Chromium. See https://bugs.chromium.org/p/chromium/issues/detail?id=992871
>> > > > > for details and reproducer.
>> > > > >
>> > > > > On Thu, Aug 8, 2019 at 10:24 PM Guozhi Wei via llvm-commits
>> > > > > <llvm-commits at lists.llvm.org> wrote:
>> > > > > >
>> > > > > > Author: carrot
>> > > > > > Date: Thu Aug 8 13:25:23 2019
>> > > > > > New Revision: 368339
>> > > > > >
>> > > > > > URL: http://llvm.org/viewvc/llvm-project?rev=368339&view=rev
>> > > > > > Log:
>> > > > > > [MBP] Disable aggressive loop rotate in plain mode
>> > > > > >
>> > > > > > Patch https://reviews.llvm.org/D43256 introduced more aggressive loop layout optimization which depends on profile information. If profile information is not available, the statically estimated profile information(generated by BranchProbabilityInfo.cpp) is used. If user program doesn't behave as BranchProbabilityInfo.cpp expected, the layout may be worse.
>> > > > > >
>> > > > > > To be conservative this patch restores the original layout algorithm in plain mode. But user can still try the aggressive layout optimization with -force-precise-rotation-cost=true.
>> > > > > >
>> > > > > > Differential Revision: https://reviews.llvm.org/D65673
>> _______________________________________________
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