[PPC] Use VSX/FP Facility integer load when an integer load's only users are conversion to FP
http://reviews.llvm.org/D18405
When the integer value loaded is never used directly as integer we should use VSX
or Floating Point Facility integer loads and avoid extra direct move
llvm-svn: 265593
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 1a1c660..70d00c2 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -6504,6 +6504,30 @@
DAG.UpdateNodeOperands(TF.getNode(), ResChain, NewResChain);
}
+/// \brief Analyze profitability of direct move
+/// prefer float load to int load plus direct move
+/// when there is no integer use of int load
+static bool directMoveIsProfitable(const SDValue &Op) {
+ SDNode *Origin = Op.getOperand(0).getNode();
+ if (Origin->getOpcode() != ISD::LOAD)
+ return true;
+
+ for (SDNode::use_iterator UI = Origin->use_begin(),
+ UE = Origin->use_end();
+ UI != UE; ++UI) {
+
+ // Only look at the users of the loaded value.
+ if (UI.getUse().get().getResNo() != 0)
+ continue;
+
+ if (UI->getOpcode() != ISD::SINT_TO_FP &&
+ UI->getOpcode() != ISD::UINT_TO_FP)
+ return true;
+ }
+
+ return false;
+}
+
/// \brief Custom lowers integer to floating point conversions to use
/// the direct move instructions available in ISA 2.07 to avoid the
/// need for load/store combinations.
@@ -6572,7 +6596,8 @@
// If we have direct moves, we can do all the conversion, skip the store/load
// however, without FPCVT we can't do most conversions.
- if (Subtarget.hasDirectMove() && Subtarget.isPPC64() && Subtarget.hasFPCVT())
+ if (Subtarget.hasDirectMove() && directMoveIsProfitable(Op) &&
+ Subtarget.isPPC64() && Subtarget.hasFPCVT())
return LowerINT_TO_FPDirectMove(Op, DAG, dl);
assert((Op.getOpcode() == ISD::SINT_TO_FP || Subtarget.hasFPCVT()) &&