Revert several FastISel commits to track down a buildbot error.

This reverts:
r215595 "[FastISel][X86] Add large code model support for materializing floating-point constants."
r215594 "[FastISel][X86] Use XOR to materialize the "0" value."
r215593 "[FastISel][X86] Emit more efficient instructions for integer constant materialization."
r215591 "[FastISel][AArch64] Make use of the zero register when possible."
r215588 "[FastISel] Let the target decide first if it wants to materialize a constant."
r215582 "[FastISel][AArch64] Cleanup constant materialization code. NFCI."

llvm-svn: 215673

1 files changed, 15 insertions, 21 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index 93a366a8546..1c2cee29a79 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -198,24 +198,29 @@ unsigned FastISel::getRegForValue(const Value *V) {
   return Reg;
 }
 
-unsigned FastISel::MaterializeConstant(const Value *V, MVT VT) {
+/// materializeRegForValue - Helper for getRegForValue. This function is
+/// called when the value isn't already available in a register and must
+/// be materialized with new instructions.
+unsigned FastISel::materializeRegForValue(const Value *V, MVT VT) {
   unsigned Reg = 0;
+
   if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
     if (CI->getValue().getActiveBits() <= 64)
       Reg = FastEmit_i(VT, VT, ISD::Constant, CI->getZExtValue());
-  } else if (isa<AllocaInst>(V))
+  } else if (isa<AllocaInst>(V)) {
     Reg = TargetMaterializeAlloca(cast<AllocaInst>(V));
-  else if (isa<ConstantPointerNull>(V))
+  } else if (isa<ConstantPointerNull>(V)) {
     // Translate this as an integer zero so that it can be
     // local-CSE'd with actual integer zeros.
     Reg =
       getRegForValue(Constant::getNullValue(DL.getIntPtrType(V->getContext())));
-  else if (const ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
-    if (CF->isNullValue())
+  } else if (const ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
+    if (CF->isNullValue()) {
       Reg = TargetMaterializeFloatZero(CF);
-    else
+    } else {
       // Try to emit the constant directly.
       Reg = FastEmit_f(VT, VT, ISD::ConstantFP, CF);
+    }
 
     if (!Reg) {
       // Try to emit the constant by using an integer constant with a cast.
@@ -248,26 +253,15 @@ unsigned FastISel::MaterializeConstant(const Value *V, MVT VT) {
     BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
             TII.get(TargetOpcode::IMPLICIT_DEF), Reg);
   }
-  return Reg;
-}
 
-/// materializeRegForValue - Helper for getRegForValue. This function is
-/// called when the value isn't already available in a register and must
-/// be materialized with new instructions.
-unsigned FastISel::materializeRegForValue(const Value *V, MVT VT) {
-  unsigned Reg = 0;
-  // Give the target-specific code a try first.
-  if (isa<Constant>(V))
+  // If target-independent code couldn't handle the value, give target-specific
+  // code a try.
+  if (!Reg && isa<Constant>(V))
     Reg = TargetMaterializeConstant(cast<Constant>(V));
 
-  // If target-specific code couldn't or didn't want to handle the value, then
-  // give target-independent code a try.
-  if (!Reg)
-    Reg = MaterializeConstant(V, VT);
-
   // Don't cache constant materializations in the general ValueMap.
   // To do so would require tracking what uses they dominate.
-  if (Reg) {
+  if (Reg != 0) {
     LocalValueMap[V] = Reg;
     LastLocalValue = MRI.getVRegDef(Reg);
   }