ART fix oat debug source map operations

Several places need to be fixed in OAT debug source map generation
(see comments in https://android-review.googlesource.com/#/c/102610/19/compiler/compiled_method.h):
1. Source Maps are deduplicated in Compiler Driver by implicit conversion
   SrcMapElems to bytes. This implies incorrect operator==.
2. SrcMapElem operator < is peculiar, and cannot be applied to
   SrcMapElems with negative to_ fields
3. SrcMap.Arrange method is not elegant

The fix is to introduce explicit conversion from SrcMapElem to one
signed 64-bit value, which is used as a base of two new operators < and ==.
They are correct and intuitive. DedupeHashFunc is changed to
explicitly convert array elements to byte, so the explicit type conversion
from SrcMapElem to byte is used.

Minor fix: In Line Table Programs the file index set command is generated
only if the index gets new value.

Change-Id: I5e2c03404a437254fc2db3485b22bfc1799b39b7
Signed-off-by: Yevgeny Rouban <yevgeny.y.rouban@intel.com>

1 files changed, 17 insertions, 36 deletions

diff --git a/compiler/compiled_method.h b/compiler/compiled_method.h
index d02cbff..36f4745 100644
--- a/compiler/compiled_method.h
+++ b/compiler/compiled_method.h
@@ -105,59 +105,40 @@ class SrcMapElem {
   uint32_t from_;
   int32_t to_;
 
+  explicit operator int64_t() const {
+    return (static_cast<int64_t>(to_) << 32) | from_;
+  }
+
   bool operator<(const SrcMapElem& sme) const {
-    uint64_t lhs = (static_cast<uint64_t>(from_) << 32) + to_;
-    uint64_t rhs = (static_cast<uint64_t>(sme.from_) << 32) + sme.to_;
-    return lhs < rhs;
+    return int64_t(*this) < int64_t(sme);
+  }
+
+  bool operator==(const SrcMapElem& sme) const {
+    return int64_t(*this) == int64_t(sme);
   }
 
-  operator uint8_t() const {
+  explicit operator uint8_t() const {
     return static_cast<uint8_t>(from_ + to_);
   }
 };
 
 class SrcMap FINAL : public std::vector<SrcMapElem> {
  public:
-  struct CompareByTo {
-    bool operator()(const SrcMapElem& lhs, const SrcMapElem& rhs) {
-      return lhs.to_ < rhs.to_;
-    }
-  };
-
-  struct CompareByFrom {
-    bool operator()(const SrcMapElem& lhs, const SrcMapElem& rhs) {
-      return lhs.from_ < rhs.from_;
-    }
-  };
-
-  void SortByTo() {
-    std::sort(begin(), end(), CompareByTo());
-  }
-
   void SortByFrom() {
-    std::sort(begin(), end(), CompareByFrom());
+    std::sort(begin(), end(), [] (const SrcMapElem& lhs, const SrcMapElem& rhs) -> bool {
+      return lhs.from_ < rhs.from_;
+    });
   }
 
   const_iterator FindByTo(int32_t to) const {
-    return std::lower_bound(begin(), end(), SrcMapElem({0, to}), CompareByTo());
+    return std::lower_bound(begin(), end(), SrcMapElem({0, to}));
   }
 
   SrcMap& Arrange() {
-    SortByTo();
-
-    // Remove duplicate pairs.
     if (!empty()) {
-      SrcMap tmp;
-      tmp.swap(*this);
-      iterator it = tmp.begin();
-      iterator prev = it;
-      it++;
-      push_back(*prev);
-      for (; it != tmp.end(); it++) {
-        if (prev->from_ != it->from_ || prev->to_ != it->to_) {
-          push_back(*(prev = it));
-        }
-      }
+      std::sort(begin(), end());
+      resize(std::unique(begin(), end()) - begin());
+      shrink_to_fit();
     }
     return *this;
   }