Check for register clobbers when merging a vreg live range with a

reserved physreg in RegisterCoalescer.

Previously, we only checked for clobbers when merging into a READ of
the physreg, but not when merging from a WRITE to the physreg.

Differential Revision: https://reviews.llvm.org/D28527

llvm-svn: 291942

1 files changed, 8 insertions, 8 deletions

diff --git a/llvm/lib/CodeGen/RegisterCoalescer.cpp b/llvm/lib/CodeGen/RegisterCoalescer.cpp
index 0f4bb59c49a..57d5b5013d8 100644
--- a/llvm/lib/CodeGen/RegisterCoalescer.cpp
+++ b/llvm/lib/CodeGen/RegisterCoalescer.cpp
@@ -1582,6 +1582,14 @@ bool RegisterCoalescer::joinReservedPhysReg(CoalescerPair &CP) {
         return false;
       }
     }
+
+    // We must also check for overlaps with regmask clobbers.
+    BitVector RegMaskUsable;
+    if (LIS->checkRegMaskInterference(RHS, RegMaskUsable) &&
+        !RegMaskUsable.test(DstReg)) {
+      DEBUG(dbgs() << "\t\tRegMask interference\n");
+      return false;
+    }
   }
 
   // Skip any value computations, we are not adding new values to the
@@ -1616,14 +1624,6 @@ bool RegisterCoalescer::joinReservedPhysReg(CoalescerPair &CP) {
           DEBUG(dbgs() << "\t\tInterference (read): " << *MI);
           return false;
         }
-
-        // We must also check for clobbers caused by regmasks.
-        for (const auto &MO : MI->operands()) {
-          if (MO.isRegMask() && MO.clobbersPhysReg(DstReg)) {
-            DEBUG(dbgs() << "\t\tInterference (regmask clobber): " << *MI);
-            return false;
-          }
-        }
       }
     }