From 8fa17424f7cb37b7a1fcf752c49396324cb5031f Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Sun, 24 Aug 2008 19:19:55 +0000 Subject: [PATCH] Move callseq_start above the call address load to allow load to be folded into the call node. llvm-svn: 55292 --- llvm/lib/Target/X86/X86ISelLowering.cpp | 9 +++++++-- llvm/test/CodeGen/X86/fold-call-2.ll | 10 ++++++++++ 2 files changed, 17 insertions(+), 2 deletions(-) create mode 100644 llvm/test/CodeGen/X86/fold-call-2.ll diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index 5d8cb1cd291a..09a30db218a1 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -1457,12 +1457,12 @@ EmitTailCallStoreRetAddr(SelectionDAG & DAG, MachineFunction &MF, SDValue X86TargetLowering::LowerCALL(SDValue Op, SelectionDAG &DAG) { MachineFunction &MF = DAG.getMachineFunction(); - SDValue Chain = Op.getOperand(0); + SDValue Chain = Op.getOperand(0); unsigned CC = cast(Op.getOperand(1))->getValue(); bool isVarArg = cast(Op.getOperand(2))->getValue() != 0; bool IsTailCall = cast(Op.getOperand(3))->getValue() != 0 && CC == CallingConv::Fast && PerformTailCallOpt; - SDValue Callee = Op.getOperand(4); + SDValue Callee = Op.getOperand(4); bool Is64Bit = Subtarget->is64Bit(); bool IsStructRet = CallIsStructReturn(Op); @@ -1499,6 +1499,11 @@ SDValue X86TargetLowering::LowerCALL(SDValue Op, SelectionDAG &DAG) { MF.getInfo()->setTCReturnAddrDelta(FPDiff); } + // If the address is a load, i.e. indirect function call, move callseq_start + // above the load. This makes it possible for the load to fold into the call. + if (Callee.Val == Chain.Val && ISD::isNormalLoad(Callee.Val) && + Chain.hasOneUse() && Callee.hasOneUse()) + Chain = Chain.getOperand(0); Chain = DAG.getCALLSEQ_START(Chain, DAG.getIntPtrConstant(NumBytes)); SDValue RetAddrFrIdx; diff --git a/llvm/test/CodeGen/X86/fold-call-2.ll b/llvm/test/CodeGen/X86/fold-call-2.ll new file mode 100644 index 000000000000..349f986830a0 --- /dev/null +++ b/llvm/test/CodeGen/X86/fold-call-2.ll @@ -0,0 +1,10 @@ +; RUN: llvm-as < %s | llc -mtriple=i386-apple-darwin | grep mov | count 1 + +@f = external global void ()* ; [#uses=1] + +define i32 @main() nounwind { +entry: + load void ()** @f, align 8 ; :0 [#uses=1] + tail call void %0( ) nounwind + ret i32 0 +}