Quick: Fix DCE to mark wide register overlaps correctly.

Previously we missed some cases of overlap with registers
coming from previous blocks.

Bug: 20640451
Change-Id: I4b32a7aaea2dea1b0b9560ae3459a4d903683f20

1 files changed, 7 insertions, 0 deletions

diff --git a/runtime/base/bit_vector.h b/runtime/base/bit_vector.h
index be4d363bf5..6e4367ac9d 100644
--- a/runtime/base/bit_vector.h
+++ b/runtime/base/bit_vector.h
@@ -20,6 +20,8 @@
 #include <stdint.h>
 #include <iterator>
 
+#include "utils.h"
+
 namespace art {
 
 class Allocator;
@@ -116,6 +118,11 @@ class BitVector {
 
   virtual ~BitVector();
 
+  // The number of words necessary to encode bits.
+  static constexpr uint32_t BitsToWords(uint32_t bits) {
+    return RoundUp(bits, kWordBits) / kWordBits;
+  }
+
   // Mark the specified bit as "set".
   void SetBit(uint32_t idx) {
     /*