You're asking about the ratio of "compiler bugs in code generation impacting behavior" to "bugs in C source code"? Obviously the number depends critically on th

You're asking about the ratio of "compiler bugs in code generation impacting behavior" to "bugs in C source code"? Obviously the number depends critically on the denominator... Defect density for DAL A software is well studied and very, very low. See, e.g., [1]. "Most estimates put the number of residual defects for a good software process at 1 to 10 per KNCSL," of which 1% are of catastrophic severity. These processes give a low enough defect rate that real-world failures are dominated by errors in the requirements process rather than in the process of converting requirements to source code; it's not hard to see that at this point compiler bugs can be non-negligible. [1] https://apps.dtic.mil/sti/pdfs/AD1088687.pdf https://apps.dtic.mil/sti/pdfs/AD1088687.pdf