add TLI support indicating that jumps are more expensive than logical operations

and use this to disable a specific optimization.  Patch by Micah Villmow!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120435 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 4 insertions, 1 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index d00643f1f1..6dfc6b53c7 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1403,6 +1403,7 @@ void SelectionDAGBuilder::visitBr(const BranchInst &I) {
 
   // If this is a series of conditions that are or'd or and'd together, emit
   // this as a sequence of branches instead of setcc's with and/or operations.
+  // As long as jumps are not expensive, this should improve performance.
   // For example, instead of something like:
   //     cmp A, B
   //     C = seteq
@@ -1417,7 +1418,8 @@ void SelectionDAGBuilder::visitBr(const BranchInst &I) {
   //     jle foo
   //
   if (const BinaryOperator *BOp = dyn_cast<BinaryOperator>(CondVal)) {
-    if (BOp->hasOneUse() &&
+    if (!TLI.isJumpExpensive() && 
+        BOp->hasOneUse() &&
         (BOp->getOpcode() == Instruction::And ||
          BOp->getOpcode() == Instruction::Or)) {
       FindMergedConditions(BOp, Succ0MBB, Succ1MBB, BrMBB, BrMBB,
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 12ca9291d9..b2c2dbb927 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -572,6 +572,7 @@ TargetLowering::TargetLowering(const TargetMachine &tm,
   SelectIsExpensive = false;
   IntDivIsCheap = false;
   Pow2DivIsCheap = false;
+  JumpIsExpensive = false;
   StackPointerRegisterToSaveRestore = 0;
   ExceptionPointerRegister = 0;
   ExceptionSelectorRegister = 0;