Only emit one entry in the exception action table for each action, even if

it occurs for multiple landing pads.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37267 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/DwarfWriter.cpp

@@ -2894,6 +2894,45 @@ private:
       O << UsedDirective << EHFrameInfo.FnName << ".eh\n\n";
   }
 
+  /// EquivPads - Whether two landing pads have equivalent actions.
+  static bool EquivPads(const LandingPadInfo *L, const LandingPadInfo *R) {
+    const std::vector<unsigned> &LIds = L->TypeIds;
+    const std::vector<unsigned> &RIds = R->TypeIds;
+    unsigned LSize = LIds.size(), RSize = RIds.size();
+
+    if (L->IsFilter != R->IsFilter)
+      return false;
+
+    if (LSize != RSize)
+      return false;
+
+    for (unsigned i = 0; i != LSize; ++i)
+      if (LIds[i] != RIds[i])
+        return false;
+
+    return true;
+  }
+
+  /// PadLT - An order on landing pads, with EquivPads as order equivalence.
+  static bool PadLT(const LandingPadInfo *L, const LandingPadInfo *R) {
+    const std::vector<unsigned> &LIds = L->TypeIds;
+    const std::vector<unsigned> &RIds = R->TypeIds;
+    unsigned LSize = LIds.size(), RSize = RIds.size();
+
+    if (L->IsFilter != R->IsFilter)
+      // Make filters come last
+      return L->IsFilter < R->IsFilter;
+
+    if (LSize != RSize)
+      return LSize < RSize;
+
+    for (unsigned i = 0; i != LSize; ++i)
+      if (LIds[i] != RIds[i])
+        return LIds[i] < RIds[i];
+
+    return false; // Equivalent
+  }
+
   /// EmitExceptionTable - Emit landpads and actions.
   ///
   /// The general organization of the table is complex, but the basic concepts
@@ -2933,13 +2972,18 @@ private:
     MMI->TidyLandingPads();
 
     const std::vector<GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
-    const std::vector<LandingPadInfo> &LandingPads = MMI->getLandingPads();
+    const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
-    if (LandingPads.empty()) return;
+    if (PadInfos.empty()) return;
 
-    // FIXME - Should fold actions for multiple landing pads.
+    // Sort the landing pads in order of their type ids.  This is used to fold
+    // duplicate actions.
+    SmallVector<const LandingPadInfo *, 32> LandingPads(PadInfos.size(), NULL);
+    for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
+      LandingPads[i] = &PadInfos[i];
+    std::sort(LandingPads.begin(), LandingPads.end(), PadLT);
 
     // Gather first action index for each landing pad site.
-    SmallVector<unsigned, 8> Actions;
+    SmallVector<unsigned, 32> Actions;
 
     // FIXME - Assume there is only one filter typeinfo list per function
     // time being.  I.E., Each call to eh_filter will have the same list.
@@ -2952,19 +2996,21 @@ private:
 
     // Look at each landing pad site to compute size.  We need the size of each
     // landing pad site info and the size of the landing pad's actions.
-    for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
-      const LandingPadInfo &LandingPad = LandingPads[i];
-      bool IsFilter = LandingPad.IsFilter;
-      unsigned SizeSiteActions = 0;
-      const std::vector<unsigned> &TypeIds = LandingPad.TypeIds;
-      unsigned SizeAction = 0;
     signed FirstAction;
 
-      if (IsFilter) {
+    for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
+      const LandingPadInfo *LandingPad = LandingPads[i];
+      unsigned SizeSiteActions = 0;
+
+      if (!i || !EquivPads(LandingPad, LandingPads[i-1])) {
+        const std::vector<unsigned> &TypeIds = LandingPad->TypeIds;
+        unsigned SizeAction = 0;
+
+        if (LandingPad->IsFilter) {
           // FIXME - Assume there is only one filter typeinfo list per function
           // time being.  I.E., Each call to eh_filter will have the same list.
           // This can change if a function is inlined.
-        Filter = &LandingPad;
+          Filter = LandingPad;
           SizeAction =  Asm->SizeSLEB128(-1) + Asm->SizeSLEB128(0);
           SizeSiteActions += SizeAction;
           // Record the first action of the landing pad site.
@@ -2984,11 +3030,13 @@ private:
           // Record the first action of the landing pad site.
           FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
         }
+      } // else re-use previous FirstAction
+
       Actions.push_back(FirstAction);
 
       // Compute this sites contribution to size.
       SizeActions += SizeSiteActions;
-      unsigned M = LandingPad.BeginLabels.size();
+      unsigned M = LandingPad->BeginLabels.size();
       SizeSites += M*(sizeof(int32_t) +               // Site start.
                       sizeof(int32_t) +               // Site length.
                       sizeof(int32_t) +               // Landing pad.
@@ -3035,9 +3083,9 @@ private:
     PadMapType PadMap;
 
     for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
-      const LandingPadInfo &LandingPad = LandingPads[i];
+      const LandingPadInfo *LandingPad = LandingPads[i];
-      for (unsigned j=0, E = LandingPad.BeginLabels.size(); j != E; ++j) {
+      for (unsigned j=0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
-        unsigned BeginLabel = LandingPad.BeginLabels[j];
+        unsigned BeginLabel = LandingPad->BeginLabels[j];
         assert(!PadMap.count(BeginLabel) && "duplicate landing pad labels!");
         PadSite P = { i, j };
         PadMap[BeginLabel] = P;
@@ -3058,27 +3106,28 @@ private:
           continue;
 
         PadSite P = L->second;
-        const LandingPadInfo &LandingPad = LandingPads[P.PadIndex];
+        const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
 
-        assert(BeginLabel == LandingPad.BeginLabels[P.SiteIndex] &&
+        assert(BeginLabel == LandingPad->BeginLabels[P.SiteIndex] &&
                "Inconsistent landing pad map!");
 
         EmitSectionOffset("label", "eh_func_begin", BeginLabel, SubprogramCount,
                           false, true);
         Asm->EOL("Region start");
 
-        EmitDifference("label", LandingPad.EndLabels[P.SiteIndex],
+        EmitDifference("label", LandingPad->EndLabels[P.SiteIndex],
                        "label", BeginLabel);
         Asm->EOL("Region length");
 
-        if (LandingPad.TypeIds.empty()) {
+        if (LandingPad->TypeIds.empty()) {
           if (TAI->getAddressSize() == sizeof(int32_t))
             Asm->EmitInt32(0);
           else
             Asm->EmitInt64(0);
         } else {
-          EmitSectionOffset("label", "eh_func_begin", LandingPad.LandingPadLabel,
+          EmitSectionOffset("label", "eh_func_begin",
-                            SubprogramCount, false, true);
+                            LandingPad->LandingPadLabel, SubprogramCount,
+                            false, true);
         }
         Asm->EOL("Landing pad");
 
@@ -3089,11 +3138,12 @@ private:
 
     // Emit the actions.
     for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
-      const LandingPadInfo &LandingPad = LandingPads[i];
+      if (!i || Actions[i] != Actions[i-1]) {
-      const std::vector<unsigned> &TypeIds = LandingPad.TypeIds;
+        const LandingPadInfo *LandingPad = LandingPads[i];
+        const std::vector<unsigned> &TypeIds = LandingPad->TypeIds;
         unsigned SizeAction = 0;
 
-      if (LandingPad.IsFilter) {
+        if (LandingPad->IsFilter) {
           Asm->EmitSLEB128Bytes(-1);
           Asm->EOL("TypeInfo index");
           Asm->EmitSLEB128Bytes(0);
@@ -3111,6 +3161,7 @@ private:
           }
         }
       }
+    }
 
     // Emit the type ids.
     for (unsigned M = TypeInfos.size(); M; --M) {