Coverage: improve efficiency of the counter propagation to the expansion regions.

This patch reduces the complexity of the two inner loops in order to speed up 
the loading of coverage data for very large functions.

llvm-svn: 214228

1 files changed, 12 insertions, 8 deletions

diff --git a/llvm/lib/ProfileData/CoverageMappingReader.cpp b/llvm/lib/ProfileData/CoverageMappingReader.cpp
index 21acae1bbdd..75ade55e2ed 100644
--- a/llvm/lib/ProfileData/CoverageMappingReader.cpp
+++ b/llvm/lib/ProfileData/CoverageMappingReader.cpp
@@ -251,15 +251,19 @@ std::error_code RawCoverageMappingReader::read(CoverageMappingRecord &Record) {
   // from the expanded file.
   // Perform multiple passes to correctly propagate the counters through
   // all the nested expansion regions.
+  SmallVector<CounterMappingRegion *, 8> FileIDExpansionRegionMapping;
+  FileIDExpansionRegionMapping.resize(VirtualFileMapping.size(), nullptr);
   for (unsigned Pass = 1, S = VirtualFileMapping.size(); Pass < S; ++Pass) {
-    for (auto &I : MappingRegions) {
-      if (I.Kind == CounterMappingRegion::ExpansionRegion) {
-        for (const auto &J : MappingRegions) {
-          if (J.FileID == I.ExpandedFileID) {
-            I.Count = J.Count;
-            break;
-          }
-        }
+    for (auto &R : MappingRegions) {
+      if (R.Kind != CounterMappingRegion::ExpansionRegion)
+        continue;
+      assert(!FileIDExpansionRegionMapping[R.ExpandedFileID]);
+      FileIDExpansionRegionMapping[R.ExpandedFileID] = &R;
+    }
+    for (auto &R : MappingRegions) {
+      if (FileIDExpansionRegionMapping[R.FileID]) {
+        FileIDExpansionRegionMapping[R.FileID]->Count = R.Count;
+        FileIDExpansionRegionMapping[R.FileID] = nullptr;
       }
     }
   }