From: Chris Lattner <sabre@nondot.org>
Date: Sat, 31 Oct 2009 22:11:15 +0000 (+0000)
Subject: Make sure PRE doesn't split crit edges from indirectbr.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=fb6e701f08d7ec065222abbbc6727dc80de3d17e;p=oota-llvm.git

Make sure PRE doesn't split crit edges from indirectbr.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85692 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index 33ad4e1059d..0e3f7507da8 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -1810,7 +1810,7 @@ bool GVN::processBlock(BasicBlock *BB) {
 
 /// performPRE - Perform a purely local form of PRE that looks for diamond
 /// control flow patterns and attempts to perform simple PRE at the join point.
-bool GVN::performPRE(Function& F) {
+bool GVN::performPRE(Function &F) {
   bool Changed = false;
   SmallVector<std::pair<TerminatorInst*, unsigned>, 4> toSplit;
   DenseMap<BasicBlock*, Value*> predMap;
@@ -1875,6 +1875,10 @@ bool GVN::performPRE(Function& F) {
       // we would need to insert instructions in more than one pred.
       if (NumWithout != 1 || NumWith == 0)
         continue;
+      
+      // Don't do PRE across indirect branch.
+      if (isa<IndirectBrInst>(PREPred->getTerminator()))
+        continue;
 
       // We can't do PRE safely on a critical edge, so instead we schedule
       // the edge to be split and perform the PRE the next time we iterate