When RemoveCopyByCommutingDef is creating additional identity copies, just use

LiveInterval::MergeValueNumberInto instead of trying to extend LiveRanges and
getting it wrong.

This fixed PR8249 where a valno with a multi-segment live range was defined by
an identity copy created by RemoveCopyByCommutingDef. Some of the live
segments disappeared.

llvm-svn: 115385

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/include/llvm/CodeGen/LiveInterval.h b/llvm/include/llvm/CodeGen/LiveInterval.h
index 706d4495169..720fb830e47 100644
--- a/llvm/include/llvm/CodeGen/LiveInterval.h
+++ b/llvm/include/llvm/CodeGen/LiveInterval.h
@@ -81,6 +81,11 @@ namespace llvm {
     unsigned getFlags() const { return flags; }
     void setFlags(unsigned flags) { this->flags = flags; }
 
+    /// Merge flags from another VNInfo
+    void mergeFlags(const VNInfo *VNI) {
+      flags = (flags | VNI->flags) & ~IS_UNUSED;
+    }
+
     /// For a register interval, if this VN was definied by a copy instr
     /// getCopy() returns a pointer to it, otherwise returns 0.
     /// For a stack interval the behaviour of this method is undefined.