search for: brcts

Hi Jonas, Are you talking specifically about the induction variable? You might look at what I did for PowerPC's counter-based loops (lib/Target/PowerPC/PPCCTRLoops.cpp, etc.). -Hal ----- Original Message ----- > From: "Jonas Paulsson via llvm-dev" <llvm-dev at lists.llvm.org> > To: "llvm-dev" <llvm-dev at lists.llvm.org> > Sent: Monday, March 28,

Hi Hal, yes, it's all about the induction variable. SystemZ has a late pass (pre-emit) that looks for MI sequences that can be rewritten to 'branch on count'. Currently only about half the number of BRCTs are output compared to gcc on the same benchmarks. One reason for this is that when a loop gets unrolled, the loop gets a greater increment / decrement than 1, which makes the late peephole transformation not work. Since LSR generates formula for induction variables and evaluates them, I thoug...

Hi, I am looking for a way to rewrite induction variables to use an addition of -1 whenever possible (and not otherwise unprofitable). This is needed to utilize hardware loop instructions, which are present on SystemZ (branch on count). Later in the backend, an 'add -1; compare w/ 0; jne 0'-sequence can be replaced with a brct instruction. I could not find any way in the LSR pass to