[llvm] r240221 - [SwitchLowering] Remove quadratic vector removal.

[Benjamin Kramer]

Author: d0k
Date: Sat Jun 20 10:59:34 2015
New Revision: 240221

URL: http://llvm.org/viewvc/llvm-project?rev=240221&view=rev
Log:
[SwitchLowering] Remove quadratic vector removal.

This can be triggered with giant switches. No functionality change
intended.

Modified:
    llvm/trunk/lib/Transforms/Utils/LowerSwitch.cpp

Modified: llvm/trunk/lib/Transforms/Utils/LowerSwitch.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LowerSwitch.cpp?rev=240221&r1=240220&r2=240221&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LowerSwitch.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LowerSwitch.cpp Sat Jun 20 10:59:34 2015
@@ -364,9 +364,9 @@ unsigned LowerSwitch::Clusterify(CaseVec
   std::sort(Cases.begin(), Cases.end(), CaseCmp());
 
   // Merge case into clusters
-  if (Cases.size()>=2)
-    for (CaseItr I = Cases.begin(), J = std::next(Cases.begin());
-         J != Cases.end();) {
+  if (Cases.size() >= 2) {
+    CaseItr I = Cases.begin();
+    for (CaseItr J = std::next(I), E = Cases.end(); J != E; ++J) {
       int64_t nextValue = J->Low->getSExtValue();
       int64_t currentValue = I->High->getSExtValue();
       BasicBlock* nextBB = J->BB;
@@ -377,11 +377,13 @@ unsigned LowerSwitch::Clusterify(CaseVec
       assert(nextValue > currentValue && "Cases should be strictly ascending");
       if ((nextValue == currentValue + 1) && (currentBB == nextBB)) {
         I->High = J->High;
-        J = Cases.erase(J);
-      } else {
-        I = J++;
+        // FIXME: Combine branch weights.
+      } else if (++I != J) {
+        *I = *J;
       }
     }
+    Cases.erase(std::next(I), Cases.end());
+  }
 
   for (CaseItr I=Cases.begin(), E=Cases.end(); I!=E; ++I, ++numCmps) {
     if (I->Low != I->High)
@@ -477,12 +479,10 @@ void LowerSwitch::processSwitchInst(Swit
     // cases.
     assert(MaxPop > 0 && PopSucc);
     Default = PopSucc;
-    for (CaseItr I = Cases.begin(); I != Cases.end();) {
-      if (I->BB == PopSucc)
-        I = Cases.erase(I);
-      else
-        ++I;
-    }
+    Cases.erase(std::remove_if(
+                    Cases.begin(), Cases.end(),
+                    [PopSucc](const CaseRange &R) { return R.BB == PopSucc; }),
+                Cases.end());
 
     // If there are no cases left, just branch.
     if (Cases.empty()) {