Constant fold shifts, turning this loop:

.LBB_Z5test0PdS__3:     # no_exit.1
        fldl data(,%eax,8)
        fldl 24(%esp)
        faddp %st(1)
        fstl 24(%esp)
        incl %eax
        movl $16000, %ecx
        sarl $3, %ecx
        cmpl %eax, %ecx
        fstpl 16(%esp)
        #FP_REG_KILL
        jg .LBB_Z5test0PdS__3   # no_exit.1

into:

.LBB_Z5test0PdS__3:     # no_exit.1
        fldl data(,%eax,8)
        fldl 24(%esp)
        faddp %st(1)
        fstl 24(%esp)
        incl %eax
        cmpl $2000, %eax
        fstpl 16(%esp)
        #FP_REG_KILL
        jl .LBB_Z5test0PdS__3   # no_exit.1


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19427 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index f3c18d37d3..224b969694 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -535,6 +535,9 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,
       case ISD::AND  : return getConstant(C1 & C2, VT);
       case ISD::OR   : return getConstant(C1 | C2, VT);
       case ISD::XOR  : return getConstant(C1 ^ C2, VT);
+      case ISD::SHL  : return getConstant(C1 << (int)C2, VT);
+      case ISD::SRL  : return getConstant(C1 >> (unsigned)C2, VT);
+      case ISD::SRA  : return getConstant(N1C->getSignExtended() >>(int)C2, VT);
       default: break;
       }