Test failure JIT/Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.sh

[VincentBu]

Run: runtime-coreclr jitstressregs 20211121.1

Failed test:

CoreCLR OSX x64 Checked jitstressregs1 @ OSX.1014.Amd64.Open

- JIT/Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.sh

CoreCLR Linux x64 Checked jitstressregs1 @ Ubuntu.1804.Amd64.Open

- JIT/Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.sh

Error message:

Assert failure(PID 89843 [0x00015ef3], Thread: 487470 [0x7702e]): Assertion failed 'paddingToAdd == paddingNeeded' in 'Benchstone.BenchF.MatInv4:Bench():bool' during 'Emit code' (IL size 321)

File: /Users/runner/work/1/s/src/coreclr/jit/emitxarch.cpp Line: 10070
Image: /private/tmp/helix/working/BC7A09DB/p/corerun
task_for_pid(89843) FAILED 5 (os/kern) failure
/private/tmp/helix/working/BC7A09DB/w/B1520973/e/JIT/Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.sh: line 379: 89843 Abort trap: 6           (core dumped) $LAUNCHER $ExePath "${CLRTestExecutionArguments[@]}"

Return code:      1
Raw output file:      /tmp/helix/working/BC7A09DB/w/B1520973/uploads/Reports/JIT.Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.output.txt
Raw output:
BEGIN EXECUTION
/tmp/helix/working/BC7A09DB/p/corerun -p System.Reflection.Metadata.MetadataUpdater.IsSupported=false MatInv4.dll ''
Expected: 100
Actual: 134
END EXECUTION - FAILED
Test Harness Exitcode is : 1
To run the test:

set CORE_ROOT=/tmp/helix/working/BC7A09DB/p
/private/tmp/helix/working/BC7A09DB/w/B1520973/e/JIT/Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.sh
Expected: True
Actual:   False


Stack trace
   at JIT_Performance._CodeQuality_Benchstones_BenchF_MatInv4_MatInv4_MatInv4_._CodeQuality_Benchstones_BenchF_MatInv4_MatInv4_MatInv4_sh()

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Issue Details

---

Run: runtime-coreclr jitstressregs 20211121.1

Failed test:

CoreCLR OSX x64 Checked jitstressregs1 @ OSX.1014.Amd64.Open

- JIT/Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.sh

CoreCLR Linux x64 Checked jitstressregs1 @ Ubuntu.1804.Amd64.Open

- JIT/Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.sh

Error message:

Assert failure(PID 89843 [0x00015ef3], Thread: 487470 [0x7702e]): Assertion failed 'paddingToAdd == paddingNeeded' in 'Benchstone.BenchF.MatInv4:Bench():bool' during 'Emit code' (IL size 321)

File: /Users/runner/work/1/s/src/coreclr/jit/emitxarch.cpp Line: 10070
Image: /private/tmp/helix/working/BC7A09DB/p/corerun
task_for_pid(89843) FAILED 5 (os/kern) failure
/private/tmp/helix/working/BC7A09DB/w/B1520973/e/JIT/Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.sh: line 379: 89843 Abort trap: 6           (core dumped) $LAUNCHER $ExePath "${CLRTestExecutionArguments[@]}"

Return code:      1
Raw output file:      /tmp/helix/working/BC7A09DB/w/B1520973/uploads/Reports/JIT.Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.output.txt
Raw output:
BEGIN EXECUTION
/tmp/helix/working/BC7A09DB/p/corerun -p System.Reflection.Metadata.MetadataUpdater.IsSupported=false MatInv4.dll ''
Expected: 100
Actual: 134
END EXECUTION - FAILED
Test Harness Exitcode is : 1
To run the test:

set CORE_ROOT=/tmp/helix/working/BC7A09DB/p
/private/tmp/helix/working/BC7A09DB/w/B1520973/e/JIT/Performance/CodeQuality/Benchstones/BenchF/MatInv4/MatInv4/MatInv4.sh
Expected: True
Actual:   False


Stack trace
   at JIT_Performance._CodeQuality_Benchstones_BenchF_MatInv4_MatInv4_MatInv4_._CodeQuality_Benchstones_BenchF_MatInv4_MatInv4_MatInv4_sh()

Author:	VincentBu
Assignees:	-
Labels:	os-linux, os-mac-os-x, JitStress, arch-x64, area-CodeGen-coreclr, untriaged
Milestone:	-

[JulieLeeMSFT]

@BruceForstall PTAL.

[BruceForstall]

@kunalspathak assert related to loop alignment (and also JitStressRegs=1?)

[kunalspathak]

This is happening precisely because of a scenario for which I added a separate flag to track if alignment flag is removed or not. But after re-thinking from #60787 (comment) I decided to remove it. Here is the scenario:

We align a loop IG04 that sometimes might contain a jmp instruction that we selected to hide the align instruction for a future loop (IG15 in this case). When we calculate the loop adjustments heuristic, we get the loop size of loop that starts at IG04. We see that IG05 contains align instruction at the end, but since we don't know yet how much padding will be added at the end of IG05, we exclude the 15 bytes padding bytes from the loop size. However, later, when we have to adjust the alignment for the loop that starts at IG15, we might decide to either not add padding at all (because of heuristics) or might add padding <= 15 bytes to it. As such the size of a loop that starts at IG04 will vary compared to the size we calculated our alignment heuristics. As such the presence of a IG that ends with alignment (align behind jmp) is misleading to our calculation and IMO, we should not align such a loop (IG04 in below example).

...
IG03:
        <align for IG04>
IG04:                            ; loop start at IG04
       ...
IG05:
      ...
      jmp ...
      <align for IG15>    ; there is another loop at IG15 and we decide to put its alignment in this block.
IG06:
      ...
      jne IG04

...

Alternatively, one may argue to why bother place align instruction for loop IG15 at the end of IG05 (which is part of a loop) rather than placing it in IG14 which is just before the loop start. We cannot do it currently because during placeLoopAlignInstructions phase, we do not have information of which BasicBlock is part of a loop. I will discuss this offline with @BruceForstall as well before going forward with this approach.