Taken into account Duncan's comments for r149481 dated by 2nd Feb 2012:

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120130/136146.html

Implemented CaseIterator and it solves almost all described issues: we don't need to mix operand/case/successor indexing anymore. Base iterator class is implemented as a template since it may be initialized either from "const SwitchInst*" or from "SwitchInst*".

ConstCaseIt is just a read-only iterator.
CaseIt is read-write iterator; it allows to change case successor and case value.

Usage of iterator allows totally remove resolveXXXX methods. All indexing convertions done automatically inside the iterator's getters.

Main way of iterator usage looks like this:
SwitchInst *SI = ... // intialize it somehow

for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd(); i != e; ++i) {
  BasicBlock *BB = i.getCaseSuccessor();
  ConstantInt *V = i.getCaseValue();
  // Do something.
}

If you want to convert case number to TerminatorInst successor index, just use getSuccessorIndex iterator's method.
If you want initialize iterator from TerminatorInst successor index, use CaseIt::fromSuccessorIndex(...) method.

There are also related changes in llvm-clients: klee and clang.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152297 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 21 insertions, 26 deletions

diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index fe05e3546a..45e6aff0ee 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -2158,10 +2158,11 @@ bool GVN::processInstruction(Instruction *I) {
     Value *SwitchCond = SI->getCondition();
     BasicBlock *Parent = SI->getParent();
     bool Changed = false;
-    for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i) {
-      BasicBlock *Dst = SI->getCaseSuccessor(i);
+    for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd();
+         i != e; ++i) {
+      BasicBlock *Dst = i.getCaseSuccessor();
       if (isOnlyReachableViaThisEdge(Parent, Dst, DT))
-        Changed |= propagateEquality(SwitchCond, SI->getCaseValue(i), Dst);
+        Changed |= propagateEquality(SwitchCond, i.getCaseValue(), Dst);
     }
     return Changed;
   }
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index fa25a8fcd7..4ef5298dc0 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -1087,8 +1087,7 @@ bool JumpThreading::ProcessThreadableEdges(Value *Cond, BasicBlock *BB,
     else if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator()))
       DestBB = BI->getSuccessor(cast<ConstantInt>(Val)->isZero());
     else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) {
-      unsigned ValCase = SI->findCaseValue(cast<ConstantInt>(Val));
-      DestBB = SI->getSuccessor(SI->resolveSuccessorIndex(ValCase));
+      DestBB = SI->findCaseValue(cast<ConstantInt>(Val)).getCaseSuccessor();
     } else {
       assert(isa<IndirectBrInst>(BB->getTerminator())
               && "Unexpected terminator");
diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index 2c75f637f4..28e0706116 100644
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -445,8 +445,9 @@ bool LoopUnswitch::processCurrentLoop() {
         // Do not process same value again and again.
         // At this point we have some cases already unswitched and
         // some not yet unswitched. Let's find the first not yet unswitched one.
-        for (unsigned i = 0; i < NumCases; ++i) {
-          Constant* UnswitchValCandidate = SI->getCaseValue(i);
+        for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd();
+             i != e; ++i) {
+          Constant* UnswitchValCandidate = i.getCaseValue();
           if (!BranchesInfo.isUnswitched(SI, UnswitchValCandidate)) {
             UnswitchVal = UnswitchValCandidate;
             break;
@@ -574,12 +575,13 @@ bool LoopUnswitch::IsTrivialUnswitchCondition(Value *Cond, Constant **Val,
     // this. 
     // Note that we can't trivially unswitch on the default case or
     // on already unswitched cases.
-    for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i) {
+    for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd();
+         i != e; ++i) {
       BasicBlock* LoopExitCandidate;
       if ((LoopExitCandidate = isTrivialLoopExitBlock(currentLoop, 
-                                               SI->getCaseSuccessor(i)))) {
+                                               i.getCaseSuccessor()))) {
         // Okay, we found a trivial case, remember the value that is trivial.
-        ConstantInt* CaseVal = SI->getCaseValue(i);
+        ConstantInt* CaseVal = i.getCaseValue();
 
         // Check that it was not unswitched before, since already unswitched
         // trivial vals are looks trivial too.
@@ -1117,16 +1119,16 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
     SwitchInst *SI = dyn_cast<SwitchInst>(U);
     if (SI == 0 || !isa<ConstantInt>(Val)) continue;
     
-    unsigned DeadCase = SI->findCaseValue(cast<ConstantInt>(Val));
+    SwitchInst::CaseIt DeadCase = SI->findCaseValue(cast<ConstantInt>(Val));
     // Default case is live for multiple values.
-    if (DeadCase == SwitchInst::ErrorIndex) continue;
+    if (DeadCase == SI->caseDefault()) continue;
     
     // Found a dead case value.  Don't remove PHI nodes in the 
     // successor if they become single-entry, those PHI nodes may
     // be in the Users list.
 
     BasicBlock *Switch = SI->getParent();
-    BasicBlock *SISucc = SI->getCaseSuccessor(DeadCase);
+    BasicBlock *SISucc = DeadCase.getCaseSuccessor();
     BasicBlock *Latch = L->getLoopLatch();
     
     BranchesInfo.setUnswitched(SI, Val);
@@ -1146,7 +1148,7 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
     // Compute the successors instead of relying on the return value
     // of SplitEdge, since it may have split the switch successor
     // after PHI nodes.
-    BasicBlock *NewSISucc = SI->getCaseSuccessor(DeadCase);
+    BasicBlock *NewSISucc = DeadCase.getCaseSuccessor();
     BasicBlock *OldSISucc = *succ_begin(NewSISucc);
     // Create an "unreachable" destination.
     BasicBlock *Abort = BasicBlock::Create(Context, "us-unreachable",
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index 4274b509d2..8d0b86606a 100644
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -564,7 +564,7 @@ void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI,
       return;
     }
 
-    Succs[SI->resolveSuccessorIndex(SI->findCaseValue(CI))] = true;
+    Succs[SI->findCaseValue(CI).getSuccessorIndex()] = true;
     return;
   }
 
@@ -623,14 +623,7 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
     if (CI == 0)
       return !SCValue.isUndefined();
 
-    // Make sure to skip the "default value" which isn't a value
-    for (unsigned i = 0, E = SI->getNumCases(); i != E; ++i)
-      if (SI->getCaseValue(i) == CI) // Found the taken branch.
-        return SI->getCaseSuccessor(i) == To;
-
-    // If the constant value is not equal to any of the branches, we must
-    // execute default branch.
-    return SI->getDefaultDest() == To;
+    return SI->findCaseValue(CI).getCaseSuccessor() == To;
   }
 
   // Just mark all destinations executable!
@@ -1495,12 +1488,12 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
       // If the input to SCCP is actually switch on undef, fix the undef to
       // the first constant.
       if (isa<UndefValue>(SI->getCondition())) {
-        SI->setCondition(SI->getCaseValue(0));
-        markEdgeExecutable(BB, SI->getCaseSuccessor(0));
+        SI->setCondition(SI->caseBegin().getCaseValue());
+        markEdgeExecutable(BB, SI->caseBegin().getCaseSuccessor());
         return true;
       }
 
-      markForcedConstant(SI->getCondition(), SI->getCaseValue(0));
+      markForcedConstant(SI->getCondition(), SI->caseBegin().getCaseValue());
       return true;
     }
   }