SimplifyCFG: Use parallel-and and parallel-or mode to consolidate branch conditions

Merge consecutive if-regions if they contain identical statements.
Both transformations reduce number of branches.  The transformation
is guarded by a target-hook, and is currently enabled only for +R600,
but the correctness has been tested on X86 target using a variety of
CPU benchmarks.

Patch by: Mei Ye

llvm-svn: 187278

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp
index 4b2bf3c770b..4ad71627bea 100644
--- a/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -88,6 +88,10 @@ unsigned TargetTransformInfo::getUserCost(const User *U) const {
   return PrevTTI->getUserCost(U);
 }
 
+bool TargetTransformInfo::hasBranchDivergence() const {
+  return PrevTTI->hasBranchDivergence();
+}
+
 bool TargetTransformInfo::isLoweredToCall(const Function *F) const {
   return PrevTTI->isLoweredToCall(F);
 }
@@ -420,6 +424,8 @@ struct NoTTI : ImmutablePass, TargetTransformInfo {
                                 U->getOperand(0)->getType() : 0);
   }
 
+  bool hasBranchDivergence() const { return false; }
+
   bool isLoweredToCall(const Function *F) const {
     // FIXME: These should almost certainly not be handled here, and instead
     // handled with the help of TLI or the target itself. This was largely