Ruby

Bug #15552

Updated by Eregon (Benoit Daloze) over 6 years ago

Specifically, the image generated is incorrect. 
 When modifying the footer of the benchmark like this: 

 ```ruby 
 alias printf_orig printf 
 def printf *args 
   $fp.printf(*args) 
 end 

 File.open("ao.ppm", "w") do |fp| 
   $fp = fp 
   printf("P6\n") 
   printf("%d %d\n", IMAGE_WIDTH, IMAGE_HEIGHT) 
   printf("255\n") 
   Scene.new.render(IMAGE_WIDTH, IMAGE_HEIGHT, NSUBSAMPLES) 
 end 

 undef printf 
 alias printf printf_orig 
 ``` 

 Here is the expected image: 
 ![ao_ref](https://user-images.githubusercontent.com/168854/51442303-dd6f8680-1cdb-11e9-89ac-e88773a384c8.png) 
 I get this image with MRI 2.6.0: 
 ![ao_mri_2_6_0](https://user-images.githubusercontent.com/168854/51442292-c7fa5c80-1cdb-11e9-9146-2ec3f447d479.png) 
 And interestingly, TruffleRuby 1.0.0-rc11 renders an image closer to the expected one: 
 ![ao_tr_rc11](https://user-images.githubusercontent.com/168854/51442298-d5174b80-1cdb-11e9-97f6-0b1fc59fcddf.png) 

 I guess this might be both an interpreter bug, and possibly also a bug in the benchmark code. source bug. 

 I think every benchmark should have some validation, otherwise it's prone to measure something unexpected like this.

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