[llvm-commits] [llvm] r37908 - in /llvm/trunk: include/llvm/CodeGen/MachineModuleInfo.h lib/CodeGen/MachineModuleInfo.cpp

[Duncan Sands]

Author: baldrick
Date: Thu Jul  5 10:15:01 2007
New Revision: 37908

URL: http://llvm.org/viewvc/llvm-project?rev=37908&view=rev
Log:
Make sure only one copy of a filter is placed in the
exception handling table if we encounter it multiple
times.  Filters could be folded harder than this, but
that would mean a lot more work for not much gain.

Modified:
    llvm/trunk/include/llvm/CodeGen/MachineModuleInfo.h
    llvm/trunk/lib/CodeGen/MachineModuleInfo.cpp

Modified: llvm/trunk/include/llvm/CodeGen/MachineModuleInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineModuleInfo.h?rev=37908&r1=37907&r2=37908&view=diff

==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineModuleInfo.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachineModuleInfo.h Thu Jul  5 10:15:01 2007
@@ -1022,6 +1022,11 @@
   //
   std::vector<unsigned> FilterIds;
 
+  // FilterEnds - List of the indices in FilterIds corresponding to filter
+  // terminators.
+  //
+  std::vector<unsigned> FilterEnds;
+
   // Personalities - Vector of all personality functions ever seen. Used to emit
   // common EH frames.
   std::vector<Function *> Personalities;

Modified: llvm/trunk/lib/CodeGen/MachineModuleInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineModuleInfo.cpp?rev=37908&r1=37907&r2=37908&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/MachineModuleInfo.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineModuleInfo.cpp Thu Jul  5 10:15:01 2007
@@ -1522,6 +1522,7 @@
   LandingPads.clear();
   TypeInfos.clear();
   FilterIds.clear();
+  FilterEnds.clear();
 }
 
 /// getDescFor - Convert a Value to a debug information descriptor.
@@ -1772,13 +1773,30 @@
 /// getFilterIDFor - Return the filter id for the specified typeinfos.  This is
 /// function wide.
 int MachineModuleInfo::getFilterIDFor(std::vector<unsigned> &TyIds) {
-  // TODO: map duplicate filters to the same filter id; a filter equal to the
-  // tail of an existing filter also need not be added; re-order filters and
-  // filter elements to maximize this kind of sharing.
+  // If the new filter coincides with the tail of an existing filter, then
+  // re-use the existing filter.  Folding filters more than this requires
+  // re-ordering filters and/or their elements - probably not worth it.
+  for (std::vector<unsigned>::iterator I = FilterEnds.begin(),
+       E = FilterEnds.end(); I != E; ++I) {
+    unsigned i = *I, j = TyIds.size();
+
+    while (i && j)
+      if (FilterIds[--i] != TyIds[--j])
+        goto try_next;
+
+    if (!j)
+      // The new filter coincides with range [i, end) of the existing filter.
+      return -(1 + i);
+
+try_next:;
+  }
+
+  // Add the new filter.
   int FilterID = -(1 + FilterIds.size());
   FilterIds.reserve(FilterIds.size() + TyIds.size() + 1);
   for (unsigned I = 0, N = TyIds.size(); I != N; ++I)
     FilterIds.push_back(TyIds[I]);
+  FilterEnds.push_back(FilterIds.size());
   FilterIds.push_back(0); // terminator
   return FilterID;
 }