A good chunk of what people (used to) term "optimization bugs" fell under that umbrella. Program works w/ optimization off, but fails w/ optimization on. Or opt

A good chunk of what people (used to) term "optimization bugs" fell under that umbrella. Program works w/ optimization off, but fails w/ optimization on. Or optimization would "fail" because of program bugs like uninitialize memory that "works" w/ optimization off. Even with old compilers, if you turned optimization on and saw problems, it was almost always an issue with the code being compiled, not the compiler. But that's often not how the blame was laid.