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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187278 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/CodeGen/BasicTargetTransformInfo.cpp b/lib/CodeGen/BasicTargetTransformInfo.cpp
index 3755320ab1..cb12a40ff0 100644
--- a/lib/CodeGen/BasicTargetTransformInfo.cpp
+++ b/lib/CodeGen/BasicTargetTransformInfo.cpp
@@ -65,6 +65,8 @@ public:
     return this;
   }
 
+  virtual bool hasBranchDivergence() const;
+
   /// \name Scalar TTI Implementations
   /// @{
 
@@ -124,6 +126,7 @@ llvm::createBasicTargetTransformInfoPass(const TargetMachine *TM) {
   return new BasicTTI(TM);
 }
 
+bool BasicTTI::hasBranchDivergence() const { return false; }
 
 bool BasicTTI::isLegalAddImmediate(int64_t imm) const {
   return getTLI()->isLegalAddImmediate(imm);