Sorry, several patches in one.

TargetInstrInfo:
Change produceSameValue() to take MachineRegisterInfo as an optional argument.
When in SSA form, targets can use it to make more aggressive equality analysis.

Machine LICM:
1. Eliminate isLoadFromConstantMemory, use MI.isInvariantLoad instead.
2. Fix a bug which prevent CSE of instructions which are not re-materializable.
3. Use improved form of produceSameValue.

ARM:
1. Teach ARM produceSameValue to look pass some PIC labels.
2. Look for operands from different loads of different constant pool entries
   which have same values.
3. Re-implement PIC GA materialization using movw + movt. Combine the pair with
   a "add pc" or "ldr [pc]" to form pseudo instructions. This makes it possible
   to re-materialize the instruction, allow machine LICM to hoist the set of
   instructions out of the loop and make it possible to CSE them. It's a bit
   hacky, but it significantly improve code quality.
4. Some minor bug fixes as well.

With the fixes, using movw + movt to materialize GAs significantly outperform the
load from constantpool method. 186.crafty and 255.vortex improved > 20%, 254.gap
and 176.gcc ~10%.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123905 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1 insertions, 6 deletions

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index f4d16fc167..a6e1fe79c1 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -2003,13 +2003,8 @@ SDValue ARMTargetLowering::LowerGlobalAddressDarwin(SDValue Op,
       return DAG.getNode(ARMISD::Wrapper, dl, PtrVT,
                                  DAG.getTargetGlobalAddress(GV, dl, PtrVT));
 
-    // FIXME: Not a constant pool!
-    unsigned PICLabelIndex = AFI->createPICLabelUId();
-    SDValue PICLabel = DAG.getConstant(PICLabelIndex, MVT::i32);
     SDValue Result = DAG.getNode(ARMISD::WrapperPIC, dl, PtrVT,
-                                 DAG.getTargetGlobalAddress(GV, dl, PtrVT),
-                                 PICLabel);
-    Result = DAG.getNode(ARMISD::PIC_ADD, dl, PtrVT, Result, PICLabel);
+                                 DAG.getTargetGlobalAddress(GV, dl, PtrVT));
     if (Subtarget->GVIsIndirectSymbol(GV, RelocM))
       Result = DAG.getLoad(PtrVT, dl, DAG.getEntryNode(), Result,
                            MachinePointerInfo::getGOT(), false, false, 0);