- User Since
- Feb 16 2021, 9:06 AM (8 w, 3 h)
Tue, Mar 16
Mon, Mar 15
@nikic As you said, as soon as the GEPs are being updated to simple arithmetic operations, PHI Translation would never be confused by GEP polymorphs. So this changeset along with this whole instruction-combining is going to be out of the picture. But still, for up until that point, I would suggest to fix this unprofitable instCombine
Mar 9 2021
There is nothing wrong with phi translation and MemoryDependencyAnalysis to fix. This changeset is not introducing a new InstCombine to fix an issue in other passes. Current implementation of InstCombine is carelessly (without doing necessary checks) combine instructions. This changeset merely prevent some of these unprofitable combines. It doesn't make sense to change other passes when the instCombine itself is introducing the problem. Even without considering MemoryDependencyAnalysis there is no benefit in combining bitcast and gep in the testcase I added. This fusion will create a GEP that uses pure byte index instead of element index in a struct.
@nikic By making a little modification in my changeset, now none of existing tests are failing. I added a new test to show how the code is supposed to look like.
Feb 22 2021
I have updated my implementation base on reviewer's comments. The only reason that I had used void* pointer detection instead of Alloc like function was to cover more cases. However, since using pointer size in optimization passes are prohibited, I changed the implementation back to Alloc like function