Defer SplitKit value mapping until all defs are available.

The greedy register allocator revealed some problems with the value mapping in
SplitKit. We would sometimes start mapping values before all defs were known,
and that could change a value from a simple 1-1 mapping to a multi-def mapping
that requires ssa update.

The new approach collects all defs and register assignments first without
filling in any live intervals. Only when finish() is called, do we compute
liveness and mapped values. At this time we know with certainty which values map
to multiple values in a split range.

This also has the advantage that we can compute live ranges based on the
remaining uses after rematerializing at split points.

The current implementation has many opportunities for compile time optimization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124765 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1 insertions, 1 deletions

diff --git a/include/llvm/CodeGen/LiveInterval.h b/include/llvm/CodeGen/LiveInterval.h
index b2915cee97..88131fbc40 100644
--- a/include/llvm/CodeGen/LiveInterval.h
+++ b/include/llvm/CodeGen/LiveInterval.h
@@ -560,7 +560,7 @@ namespace llvm {
 
     /// getEqClass - Classify creates equivalence classes numbered 0..N. Return
     /// the equivalence class assigned the VNI.
-    unsigned getEqClass(const VNInfo *VNI) { return eqClass_[VNI->id]; }
+    unsigned getEqClass(const VNInfo *VNI) const { return eqClass_[VNI->id]; }
 
     /// Distribute - Distribute values in LIV[0] into a separate LiveInterval
     /// for each connected component. LIV must have a LiveInterval for each