[TLI] Add a new hook to TargetLowering to query the target if a load of a constant should be converted to simply the constant itself.

Before this patch we used getIntImmCost from TargetTransformInfo to determine if
a load of a constant should be converted to just a constant, but the threshold
for this was set to an arbitrary value. This value works well for the two
targets (X86 and ARM) that implement this target-hook, but it isn't
target-independent at all.

Now targets have the possibility to decide directly if this optimization should
be performed. The default value is set to false to preserve the current
behavior. The target hook has been moved to TargetLowering, which removed the
last use and need of TargetTransformInfo in SelectionDAG.

llvm-svn: 200271

1 files changed, 4 insertions, 8 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 430736aa46f..3aa3976322a 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -18,7 +18,6 @@
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
-#include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineConstantPool.h"
@@ -887,7 +886,7 @@ unsigned SelectionDAG::getEVTAlignment(EVT VT) const {
 
 // EntryNode could meaningfully have debug info if we can find it...
 SelectionDAG::SelectionDAG(const TargetMachine &tm, CodeGenOpt::Level OL)
-  : TM(tm), TSI(*tm.getSelectionDAGInfo()), TTI(0), TLI(0), OptLevel(OL),
+  : TM(tm), TSI(*tm.getSelectionDAGInfo()), TLI(0), OptLevel(OL),
     EntryNode(ISD::EntryToken, 0, DebugLoc(), getVTList(MVT::Other)),
     Root(getEntryNode()), NewNodesMustHaveLegalTypes(false),
     UpdateListeners(0) {
@@ -895,10 +894,8 @@ SelectionDAG::SelectionDAG(const TargetMachine &tm, CodeGenOpt::Level OL)
   DbgInfo = new SDDbgInfo();
 }
 
-void SelectionDAG::init(MachineFunction &mf, const TargetTransformInfo *tti,
-                        const TargetLowering *tli) {
+void SelectionDAG::init(MachineFunction &mf, const TargetLowering *tli) {
   MF = &mf;
-  TTI = tti;
   TLI = tli;
   Context = &mf.getFunction()->getContext();
 }
@@ -3575,9 +3572,8 @@ static SDValue getMemsetStringVal(EVT VT, SDLoc dl, SelectionDAG &DAG,
 
   // If the "cost" of materializing the integer immediate is less than the cost
   // of a load, then it is cost effective to turn the load into the immediate.
-  const TargetTransformInfo *TTI = DAG.getTargetTransformInfo();
-  if (TTI->getIntImmCost(Val, VT.getTypeForEVT(*DAG.getContext())) <
-      TargetTransformInfo::TCC_Load)
+  Type *Ty = VT.getTypeForEVT(*DAG.getContext());
+  if (TLI.shouldConvertConstantLoadToIntImm(Val, Ty))
     return DAG.getConstant(Val, VT);
   return SDValue(0, 0);
 }