Teach SimplifyCFG how to simplify indirectbr instructions.

 - Eliminate redundant successors.
 - Convert an indirectbr with one successor into a direct branch.

Also, generalize SimplifyCFG to be able to be run on a function entry block.
It knows quite a few simplifications which are applicable to the entry
block, and it only needs a few checks to avoid trouble with the entry block.

llvm-svn: 111060

1 files changed, 2 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
index df6ef2ee75b..360749caf11 100644
--- a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
+++ b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
@@ -285,10 +285,9 @@ static bool IterativeSimplifyCFG(Function &F, const TargetData *TD) {
   while (LocalChange) {
     LocalChange = false;
     
-    // Loop over all of the basic blocks (except the first one) and remove them
-    // if they are unneeded...
+    // Loop over all of the basic blocks and remove them if they are unneeded...
     //
-    for (Function::iterator BBIt = ++F.begin(); BBIt != F.end(); ) {
+    for (Function::iterator BBIt = F.begin(); BBIt != F.end(); ) {
       if (SimplifyCFG(BBIt++, TD)) {
         LocalChange = true;
         ++NumSimpl;