[vm][flutter][android] Logs are truncated at 1024 characters

[dcharkes]

In Flutter, Dart VM logs are truncated at 1024 characters:

E/DartVM  ( 6593): *** BEGIN CFG
E/DartVM  ( 6593): Unoptimized Compilation
E/DartVM  ( 6593): ==== package:flutter/src/rendering/proxy_box.dart_RenderAnnotatedRegion_set_value (SetterFunction)
E/DartVM  ( 6593): B0[graph]:0
E/DartVM  ( 6593): B1[function entry]:2
E/DartVM  ( 6593):     Constant(#0)
E/DartVM  ( 6593):     CheckStackOverflow:8(stack=0, loop=0)
E/DartVM  ( 6593):     DebugStepCheck:10()
E/DartVM  ( 6593):     t0 <- LoadLocal(newValue @1)
E/DartVM  ( 6593):     t1 <- Constant(#TypeParameter: X0; bound: Object)
E/DartVM  ( 6593):     t2 <- LoadLocal(this @2)
E/DartVM  ( 6593):     t2 <- LoadField(t2 . :type_arguments {final})
E/DartVM  ( 6593):     t3 <- Constant(#null)
E/DartVM  ( 6593):     t0 <- AssertAssignable:12(t0, t1, 'newValue', instantiator_type_args(t2), function_type_args(t3))
E/DartVM  ( 6593):     StoreLocal(newValue @1, t0)
E/DartVM  ( 6593):     goto:48 B5
E/DartVM  ( 6593): B6[function entry]:46
E/DartVM  ( 6593):     Constant(#1)
E/DartVM  ( 6593):     CheckStackOverflow:40(stack=0, loop=0)
E/DartVM  ( 6593):     DebugStepCheck:42()
E/DartVM  ( 6593):     goto:50 B5
E/DartVM  ( 6593): B5[join]:44 pred(B1, B6)
E/DartVM  ( 6593):     t0 <- LoadLocal(this @2)
E/DartVM  ( 6593):     t0 <- InstanceCall:14( get:_value@469160605<0>, t0)
E/DartVM  ( 6593):     t1 <- LoadLocal(newValue @1)
E/DartVM  ( 6593):     t0 <- InstanceCall:16( ==<0>, t0, t1 using unchecked entrypoint)
E/DartVM  ( 6593):     t1 <- LoadLocal(:t0 @-2)
E/DartVM  ( 6593):     AssertBoolean:18(t1)
E/DartVM  ( 6593):     t1 <- Constant(#true)
E/DartVM  ( 6593):     Branch if St
E/DartVM  ( 6593): *** BEGIN CFG
E/DartVM  ( 6593): Unoptimized Compilation

*** BEGIN CFG
Unoptimized Compilation
==== package:flutter/src/rendering/proxy_box.dart_RenderAnnotatedRegion_set_value (SetterFunction)
B0[graph]:0
B1[function entry]:2
    Constant(#0)
    CheckStackOverflow:8(stack=0, loop=0)
    DebugStepCheck:10()
    t0 <- LoadLocal(newValue @1)
    t1 <- Constant(#TypeParameter: X0; bound: Object)
    t2 <- LoadLocal(this @2)
    t2 <- LoadField(t2 . :type_arguments {final})
    t3 <- Constant(#null)
    t0 <- AssertAssignable:12(t0, t1, 'newValue', instantiator_type_args(t2), function_type_args(t3))
    StoreLocal(newValue @1, t0)
    goto:48 B5
B6[function entry]:46
    Constant(#1)
    CheckStackOverflow:40(stack=0, loop=0)
    DebugStepCheck:42()
    goto:50 B5
B5[join]:44 pred(B1, B6)
    t0 <- LoadLocal(this @2)
    t0 <- InstanceCall:14( get:_value@469160605<0>, t0)
    t1 <- LoadLocal(newValue @1)
    t0 <- InstanceCall:16( ==<0>, t0, t1 using unchecked entrypoint)
    t1 <- LoadLocal(:t0 @-2)
    AssertBoolean:18(t1)
    t1 <- Constant(#true)
    Branch if St

The above is exactly 1024 characters.

Related Flutter issue with a Dart workaround: flutter/flutter#22665

To reproduce this use a custom engine which allows all DartVM flags: flutter run --local-engine=android_debug_unopt_x86 --local-engine-src-path=$HOME/flt/engine/src -d emu --dart-flags --print-flow-graph,--print-flow-graph-filter=...

[dcharkes]

Workaround: flutter run --local-engine=android_debug_unopt_x86 --local-engine-src-path=$HOME/flt/engine/src -d emu --dart-flags --print-flow-graph,--print-flow-graph-filter=convertYUV420ToImage,--force-log-flush

However, that causes many extra newlines:

E/DartVM  (11212): *** BEGIN CFG
E/DartVM  (11212): Unoptimized Compilation
E/DartVM  (11212): ==== package:flutter_match/tflite/camera_utils.dart_CameraUtils_convertYUV420ToImage (RegularFunction
E/DartVM  (11212): )
E/DartVM  (11212): B0[graph]:0
E/DartVM  (11212): 
E/DartVM  (11212): B1[function entry]:2
E/DartVM  (11212): 
E/DartVM  (11212):     
E/DartVM  (11212): CheckStackOverflow:8(stack=0, loop=0)
E/DartVM  (11212): 
E/DartVM  (11212):     
E/DartVM  (11212): DebugStepCheck:10()
E/DartVM  (11212): 
E/DartVM  (11212):     
E/DartVM  (11212): t0 <- LoadLocal(cameraImage @1)
E/DartVM  (11212): 
E/DartVM  (11212):     
E/DartVM  (11212): t0 <- InstanceCall:12( get:width<0>, t0)
E/DartVM  (11212): 
E/DartVM  (11212):     
E/DartVM  (11212): StoreLocal(width @-1, t0)
E/DartVM  (11212): 
E/DartVM  (11212):     
E/DartVM  (11212): t0 <- LoadLocal(cameraImage @1)
E/DartVM  (11212): 
E/DartVM  (11212):     
E/DartVM  (11212): t0 <- InstanceCall:14( get:height<0>, t0)
E/DartVM  (11212): 
E/DartVM  (11212):     
E/DartVM  (11212): StoreLocal(height @-2, t0)
E/DartVM  (11212): 
E/DartVM  (11212):