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%.

llvm-svn: 123905

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp b/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp
index 5fc7f323079..787c2712e75 100644
--- a/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp
@@ -166,8 +166,10 @@ void TargetInstrInfoImpl::reMaterialize(MachineBasicBlock &MBB,
   MBB.insert(I, MI);
 }
 
-bool TargetInstrInfoImpl::produceSameValue(const MachineInstr *MI0,
-                                           const MachineInstr *MI1) const {
+bool
+TargetInstrInfoImpl::produceSameValue(const MachineInstr *MI0,
+                                      const MachineInstr *MI1,
+                                      const MachineRegisterInfo *MRI) const {
   return MI0->isIdenticalTo(MI1, MachineInstr::IgnoreVRegDefs);
 }