My suspicion is about the expression folding change in r13900. Expression folding will be some what different on PPC than Intel as we don't generate conditional moves for PPC. This means we can be stressing the folding of operators and ifcmps together more. PPC should show greater benefit than Intel from expression folding as a number of the expression folding rules are similar to what we do on Intel in BURS. Anyway, I need time and a PPC to narrow down what the bug is. For now we could try disabling some of the expression folding rules using the boolean at the top of the file. I have disabled folding over uninterruptible regions in r13906. Folding references and ifcmps could also be the source of the problem.