[PATCH] D16693: Make sure all subranges are define during re-materialization of constants in RegCoalescer

[Marcello Maggioni via llvm-commits]

kariddi added a comment.

Thanks Mathias for all the comments!

I'm working on the new patch with your suggestions addressed.

The final commit would be split in two (fix + verifier).


================
Comment at: lib/CodeGen/MachineVerifier.cpp:1734-1737
@@ +1733,6 @@
+        }
+        // If any lane didn't have a proper definition report.
+        if (LiveMask != MaxMask)
+          report("Lane mask defined but no sub range reports its definition",
+                 MF);
+      }
----------------
MatzeB wrote:
> I think you can make this test more powerful if you leave out the if (MO.getSubReg() == 0) above and instead do something like this here:
> 
> ```
> LaneBitmask MOMask = TRI->getSubRegIndexLaneMask(MO.getSubReg());
> if ( (LiveMask & MOMask) != MOMask) { report(...); }
> ```
Actually this doesn't seem to be equivalent to what was there before. If getSubReg() returns 0 I get the mask ~0U from getSubRegIndexLaneMask

Would that work if I made that:


```
        LaneBitmask MOMask = TRI->getSubRegIndexLaneMask(MO.getSubReg()) & MaxMask;
        if ((LiveMask & MOMask) != MOMask) {
          report("Lane mask defined but no sub range reports its definition",
                 MF);
        }
```


Repository:
  rL LLVM

http://reviews.llvm.org/D16693