Bug 29395 - Broken instance method intrinsics in the JIT
Summary: Broken instance method intrinsics in the JIT
Alias: None
Product: Runtime
Classification: Mono
Component: JIT ()
Version: unspecified
Hardware: All All
: --- major
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2015-04-24 18:10 UTC by Alex Rønne Petersen
Modified: 2015-05-01 13:34 UTC (History)
3 users (show)

Is this bug a regression?: ---
Last known good build:

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Description Alex Rønne Petersen 2015-04-24 18:10:19 UTC
Test case 1:

using System;
public class Tests {
 public static void Main (String[] args) {
  string s = "ABC";
  for (int j = 0; j < 10000; ++j) {
   for (int i = 0; i < 100000; ++i) {
    char c = s [args.Length];

Takes ~2.5 secs, takes ~0.9 secs with the fix.

Test case 2:

using System;
class Program {
 static int Main () {
  var s = "abcd";
  s = s.PadRight (int.MaxValue);
  for (int i = s.Length - 1; i >= 0; i -= 2048) {
   if (s [i] != ' ') {
    Console.WriteLine ("incorrect at {0}", i);
  return 0;

This test case crashes before the fix.
Comment 2 Mohit Kheterpal 2015-04-27 14:39:48 UTC
Hi Alex,

I have tried to verify this issue but I am getting out of memory exception at line 
> s = s.PadRight (int.MaxValue); in test case 2

Could you please let me know with which build of mono should I reproduce this issue and with which version of mono should I check to verify it ?
Comment 3 Mohit Kheterpal 2015-04-28 06:00:45 UTC
I have checked the first test case and it seems that the performance is improved with the new mono i.e. MonoFramework-MDK-

With old mono i.e. : ~.87ms Screencast : http://www.screencast.com/t/g4HlZZ9V
with new mono i.e. ~.12ms Screencast : http://www.screencast.com/t/CLC6ph1p0

Hence closing this issue.

Comment 4 Mohit Kheterpal 2015-05-01 13:34:05 UTC
I have checked this issue again and this issue is working fine with C5 build of Mono

Hence closing this issue.