[Triton-MLIR][Backend] Add ReduceOpConversion into TritonGPUToLLVM conversion (#774)

What is done in this PR:
- [x] Add `ConvertLayout`, `getSizePerThread` and `getShapePerCTA`
implementation for `SliceEncodingAttr`
- [x] Split `emitIndices` into two phases:
`emitBaseIndexForBlockedLayout` and `emitOffsetForBlockedLayout`
- [x] Add `ReduceOpConversion::matchAndRewriteBasic` implementation
- [x] Add `ReduceOpConversion::matchAndRewriteFast` implementation with
ptx instruction `shfl.sync`
- [x] Add support for scalar value in `StoreOpConversion`
- [x] Add Reduce1d and Reduce2d unit tests and pass all unit tests

Co-authored-by: Qingyi Liu <liuqingyi1993@gmail.com>

include/triton/Analysis/Allocation.h

@@ -6,6 +6,7 @@
 #include "llvm/ADT/SetVector.h"
 #include "llvm/Support/raw_ostream.h"
 
+#include "triton/Dialect/Triton/IR/Dialect.h"
 #include "triton/Dialect/TritonGPU/IR/Dialect.h"
 #include <atomic>
 #include <limits>
@@ -19,6 +20,8 @@ SmallVector<unsigned>
 getScratchConfigForCvtLayout(triton::gpu::ConvertLayoutOp op, unsigned &inVec,
                              unsigned &outVec);
 
+SmallVector<unsigned> getScratchConfigForReduce(triton::ReduceOp op);
+
 } // namespace triton
 
 /// Modified from llvm-15.0: llvm/ADT/AddressRanges.h

include/triton/Conversion/TritonGPUToLLVM/PtxAsmFormat.h

@@ -250,6 +250,12 @@ struct PTXIOInstr : public PTXInstrBase<PTXIOInstr> {
     return *this;
   }
 
+  // Add ".shared" suffix to instruction
+  PTXIOInstr &shared(bool predicate = true) {
+    o("shared", predicate);
+    return *this;
+  }
+
   // Add ".v" suffix to instruction
   PTXIOInstr &v(int vecWidth, bool predicate = true) {
     if (vecWidth > 1) {

include/triton/Dialect/TritonGPU/IR/TritonGPUAttrDefs.td

@@ -324,7 +324,9 @@ def SliceEncodingAttr : DistributedEncoding<"SliceEncoding"> {
     "Attribute":$parent
   );
 
-  let extraClassDeclaration = extraBaseClassDeclaration;
+  let extraClassDeclaration = extraBaseClassDeclaration # [{
+    SmallVector<int64_t> paddedShape(ArrayRef<int64_t> shape) const;
+  }];
 }