Generalize ExtendUsesToFormExtLoad to be usable for ANY_EXTEND,
in addition to ZERO_EXTEND and SIGN_EXTEND. Fix a bug in the
way it checked for live-out values, and simplify the way it
find users by using SDNode::use_iterator's (relatively) new
features. Also, make it slightly more permissive on targets
with free truncates.
In SelectionDAGBuild, avoid creating ANY_EXTEND nodes that are
larger than necessary. If the target's SwitchAmountTy has
enough bits, use it. This exposes the truncate to optimization
early, enabling more optimizations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68670 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
index fd15603..d46c9c0 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
@@ -2190,8 +2190,24 @@
void SelectionDAGLowering::visitShift(User &I, unsigned Opcode) {
SDValue Op1 = getValue(I.getOperand(0));
SDValue Op2 = getValue(I.getOperand(1));
- if (!isa<VectorType>(I.getType())) {
- if (TLI.getPointerTy().bitsLT(Op2.getValueType()))
+ if (!isa<VectorType>(I.getType()) &&
+ Op2.getValueType() != TLI.getShiftAmountTy()) {
+ // If the operand is smaller than the shift count type, promote it.
+ if (TLI.getShiftAmountTy().bitsGT(Op2.getValueType()))
+ Op2 = DAG.getNode(ISD::ANY_EXTEND, getCurDebugLoc(),
+ TLI.getShiftAmountTy(), Op2);
+ // If the operand is larger than the shift count type but the shift
+ // count type has enough bits to represent any shift value, truncate
+ // it now. This is a common case and it exposes the truncate to
+ // optimization early.
+ else if (TLI.getShiftAmountTy().getSizeInBits() >=
+ Log2_32_Ceil(Op2.getValueType().getSizeInBits()))
+ Op2 = DAG.getNode(ISD::TRUNCATE, getCurDebugLoc(),
+ TLI.getShiftAmountTy(), Op2);
+ // Otherwise we'll need to temporarily settle for some other
+ // convenient type; type legalization will make adjustments as
+ // needed.
+ else if (TLI.getPointerTy().bitsLT(Op2.getValueType()))
Op2 = DAG.getNode(ISD::TRUNCATE, getCurDebugLoc(),
TLI.getPointerTy(), Op2);
else if (TLI.getPointerTy().bitsGT(Op2.getValueType()))