Use TargetTransformInfo to control switch-to-lookup table transformation

When the switch-to-lookup tables transform landed in SimplifyCFG, it
was pointed out that this could be inappropriate for some targets.
Since there was no way at the time for the pass to know anything about
the target, an awkward reverse-transform was added in CodeGenPrepare
that turned lookup tables back into switches for some targets.

This patch uses the new TargetTransformInfo to determine if a
switch should be transformed, and removes
CodeGenPrepare::ConvertLoadToSwitch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167011 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 1 deletions

diff --git a/include/llvm/Transforms/Utils/Local.h b/include/llvm/Transforms/Utils/Local.h
index 49eeb57..5c804d8 100644
--- a/include/llvm/Transforms/Utils/Local.h
+++ b/include/llvm/Transforms/Utils/Local.h
@@ -37,6 +37,7 @@ class AllocaInst;
 class ConstantExpr;
 class DataLayout;
 class TargetLibraryInfo;
+class TargetTransformInfo;
 class DIBuilder;
 
 template<typename T> class SmallVectorImpl;
@@ -134,7 +135,8 @@ bool EliminateDuplicatePHINodes(BasicBlock *BB);
 /// of the CFG.  It returns true if a modification was made, possibly deleting
 /// the basic block that was pointed to.
 ///
-bool SimplifyCFG(BasicBlock *BB, const DataLayout *TD = 0);
+bool SimplifyCFG(BasicBlock *BB, const DataLayout *TD = 0,
+                 const TargetTransformInfo *TTI = 0);
 
 /// FoldBranchToCommonDest - If this basic block is ONLY a setcc and a branch,
 /// and if a predecessor branches to us and one of our successors, fold the