Implement the first half of LiveDebugVariables.

Scan the MachineFunction for DBG_VALUE instructions, and replace them with a
data structure similar to LiveIntervals. The live range of a DBG_VALUE is
determined by propagating it down the dominator tree until a new DBG_VALUE is
found. When a DBG_VALUE lives in a register, its live range is confined to the
live range of the register's value.

LiveDebugVariables runs before coalescing, so DBG_VALUEs are not artificially
extended when registers are joined.

The missing half will recreate DBG_VALUE instructions from the intervals when
register allocation is complete.

The pass is disabled by default. It can be enabled with the temporary command
line option -live-debug-variables.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120636 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 14 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/SlotIndexes.h b/include/llvm/CodeGen/SlotIndexes.h
index c8f26544f0..fd965fc290 100644
--- a/include/llvm/CodeGen/SlotIndexes.h
+++ b/include/llvm/CodeGen/SlotIndexes.h
@@ -773,6 +773,20 @@ namespace llvm {
   };
 
 
+  // Specialize IntervalMapInfo for half-open slot index intervals.
+  template <typename> struct IntervalMapInfo;
+  template <> struct IntervalMapInfo<SlotIndex> {
+    static inline bool startLess(const SlotIndex &x, const SlotIndex &a) {
+      return x < a;
+    }
+    static inline bool stopLess(const SlotIndex &b, const SlotIndex &x) {
+      return b <= x;
+    }
+    static inline bool adjacent(const SlotIndex &a, const SlotIndex &b) {
+      return a == b;
+    }
+  };
+
 }
 
 #endif // LLVM_CODEGEN_LIVEINDEX_H