Output divergence

[aartbik]

Isolate (/b/s/w/itt9jC7a/dart_fuzzAONVOA) FP NO-FFI FLAT : KBC-MIX-DebugIA32 - JIT-OPTCOUNTER-SLOWPATH-ReleaseSIMARM: !DIVERGENCE! 1.59:1050843418 (output)

-- BEGIN REPRODUCE  --

dartfuzz.dart --fp --no-ffi --flat --seed 1050843418 /b/s/w/itt9jC7a/dart_fuzzAONVOA/fuzz.dart

-- RUN 1 --

/b/s/w/ir/pkg/vm/tool/gen_kernel --gen-bytecode --platform=/b/s/w/ir/out/DebugIA32/vm_platform_strong.dill -o /b/s/w/itt9jC7a/dart_fuzzAONVOA/out.dill /b/s/w/itt9jC7a/dart_fuzzAONVOA/fuzz.dart
/b/s/w/ir/out/DebugIA32/dart --enable-interpreter --old_gen_heap_size=128 /b/s/w/itt9jC7a/dart_fuzzAONVOA/out.dill

-- RUN 2 --

/b/s/w/ir/out/ReleaseSIMARM/dart --optimization_counter_threshold=1 --use-slow-path --old_gen_heap_size=128 /b/s/w/itt9jC7a/dart_fuzzAONVOA/fuzz.dart

-- END REPRODUCE  --

[aartbik]

Confirmed difference for the SIMARM JIT run:

< [-nan, -nan, -nan, -nan]
---
> [inf, inf, inf, inf]

fuzz.dart.txt

[alexmarkov]

The small repro:

import 'dart:typed_data';

Float32x4 var16 = new Float32x4(1.0, 1.0, 1.0, 1.0);

main() {
  for (int i = 0; i < 10; ++i) {
    print(var16 / Float32x4.zero());
  }
}

out/ReleaseSIMARM/dart --optimization_counter_threshold=5 foo.dart
[inf, inf, inf, inf]
[inf, inf, inf, inf]
[-nan, -nan, -nan, -nan]
[-nan, -nan, -nan, -nan]
[-nan, -nan, -nan, -nan]
[-nan, -nan, -nan, -nan]
[-nan, -nan, -nan, -nan]
[-nan, -nan, -nan, -nan]
[-nan, -nan, -nan, -nan]
[-nan, -nan, -nan, -nan]

It looks like this problem was already reported (#26675), fixed (3da9c34), but the fix was reverted (2cb8062).

@mraleph do you have any plans to reland the fix?

[mraleph]

I somehow missed that my commit was reverted. I will rebase and try relanding.