From f0ef882828bd9ba13cefce9869bde8be5e854956 Mon Sep 17 00:00:00 2001 From: Ulrich Weigand Date: Thu, 16 May 2013 14:53:05 +0000 Subject: [PowerPC] Report true displacement value from getPreIndexedAddressParts DAGCombiner::CombineToPreIndexedLoadStore calls a target routine to decompose a memory address into a base/offset pair. It expects the offset (if constant) to be the true displacement value in order to perform optional additional optimizations; in particular, to convert other uses of the original pointer into uses of the new base pointer after pre-increment. The PowerPC implementation of getPreIndexedAddressParts, however, simply calls SelectAddressRegImm, which returns a TargetConstant. This value is appropriate for encoding into the instruction, but it is not always usable as true displacement value: - Its type is always MVT::i32, even on 64-bit, where addresses ought to be i64 ... this causes the optimization to simply always fail on 64-bit due to this line in DAGCombiner: // FIXME: In some cases, we can be smarter about this. if (Op1.getValueType() != Offset.getValueType()) { - Its value is truncated to an unsigned 16-bit value if negative. This causes the above opimization to generate wrong code. This patch fixes both problems by simply returning the true displacement value (in its original type). This doesn't affect any other user of the displacement. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182012 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/PowerPC/PPCISelLowering.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'lib') diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp index 3e65606c43..84cf8f6a57 100644 --- a/lib/Target/PowerPC/PPCISelLowering.cpp +++ b/lib/Target/PowerPC/PPCISelLowering.cpp @@ -1061,7 +1061,7 @@ bool PPCTargetLowering::SelectAddressRegImm(SDValue N, SDValue &Disp, if (N.getOpcode() == ISD::ADD) { short imm = 0; if (isIntS16Immediate(N.getOperand(1), imm)) { - Disp = DAG.getTargetConstant((int)imm & 0xFFFF, MVT::i32); + Disp = DAG.getTargetConstant(imm, N.getValueType()); if (FrameIndexSDNode *FI = dyn_cast(N.getOperand(0))) { Base = DAG.getTargetFrameIndex(FI->getIndex(), N.getValueType()); } else { @@ -1093,7 +1093,7 @@ bool PPCTargetLowering::SelectAddressRegImm(SDValue N, SDValue &Disp, // If all of the bits are known zero on the LHS or RHS, the add won't // carry. Base = N.getOperand(0); - Disp = DAG.getTargetConstant((int)imm & 0xFFFF, MVT::i32); + Disp = DAG.getTargetConstant(imm, N.getValueType()); return true; } } -- cgit v1.2.3