YJIT: Fix raw sample stack lengths in exit traces (#7728)

yjit-trace-exits appends a synthetic sample for the instruction being
exited, but we didn't increment the size of the stack. Fixing this count
correctly lets us successfully generate a flamegraph from the exits.

I also replaced the line number for instructions with 0, as I don't
think the previous value had meaning.

Co-authored-by: Adam Hess <HParker@github.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/yjit.rb b/yjit.rb
index 60a263c322..b2af7ef0be 100644
--- a/yjit.rb
+++ b/yjit.rb
@@ -67,7 +67,7 @@ module RubyVM::YJIT
     # [ length, line_1, line_2, line_n, ..., dummy value, count
     i = 0
     while i < raw_samples.length
-      stack_length = raw_samples[i] + 1
+      stack_length = raw_samples[i]
       i += 1 # consume the stack length
 
       sample_count = raw_samples[i + stack_length]