[MLIR][LLVM] Use ViewLikeOpInterface (llvm#111663)

This commit adds the ViewLikeOpInterface to the GEP and AddrSpaceCast
operations. This allows us to simplify the inliner interface. At the
same time, the change also makes the inliner interface more extensible
for downstream users that have custom view-like operations.

Author: gysit

mlir/include/mlir/Dialect/LLVMIR/LLVMDialect.h

@@ -29,6 +29,7 @@
 #include "mlir/Interfaces/FunctionInterfaces.h"
 #include "mlir/Interfaces/InferTypeOpInterface.h"
 #include "mlir/Interfaces/SideEffectInterfaces.h"
+#include "mlir/Interfaces/ViewLikeInterface.h"
 #include "mlir/Support/ThreadLocalCache.h"
 #include "llvm/ADT/PointerEmbeddedInt.h"
 #include "llvm/IR/DerivedTypes.h"

mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td

@@ -24,6 +24,7 @@ include "mlir/Interfaces/ControlFlowInterfaces.td"
 include "mlir/Interfaces/InferTypeOpInterface.td"
 include "mlir/Interfaces/MemorySlotInterfaces.td"
 include "mlir/Interfaces/SideEffectInterfaces.td"
+include "mlir/Interfaces/ViewLikeInterface.td"
 
 class LLVM_Builder<string builder> {
   string llvmBuilder = builder;
@@ -246,7 +247,9 @@ def LLVM_AllocaOp : LLVM_Op<"alloca",
 def LLVM_GEPOp : LLVM_Op<"getelementptr", [Pure,
     DeclareOpInterfaceMethods<PromotableOpInterface>,
     DeclareOpInterfaceMethods<SafeMemorySlotAccessOpInterface>,
-    DeclareOpInterfaceMethods<DestructurableAccessorOpInterface>]> {
+    DeclareOpInterfaceMethods<DestructurableAccessorOpInterface>,
+    DeclareOpInterfaceMethods<ViewLikeOpInterface>
+    ]> {
   let arguments = (ins LLVM_ScalarOrVectorOf<LLVM_AnyPointer>:$base,
                    Variadic<LLVM_ScalarOrVectorOf<AnySignlessInteger>>:$dynamicIndices,
                    DenseI32ArrayAttr:$rawConstantIndices,
@@ -495,7 +498,8 @@ def LLVM_BitcastOp : LLVM_CastOp<"bitcast", "BitCast", LLVM_AnyNonAggregate,
 def LLVM_AddrSpaceCastOp : LLVM_CastOp<"addrspacecast", "AddrSpaceCast",
     LLVM_ScalarOrVectorOf<LLVM_AnyPointer>,
     LLVM_ScalarOrVectorOf<LLVM_AnyPointer>,
-    [DeclareOpInterfaceMethods<PromotableOpInterface>]> {
+    [DeclareOpInterfaceMethods<PromotableOpInterface>,
+     DeclareOpInterfaceMethods<ViewLikeOpInterface>]> {
   let hasFolder = 1;
 }
 def LLVM_IntToPtrOp : LLVM_CastOp<"inttoptr", "IntToPtr",

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

@@ -3226,6 +3226,8 @@ OpFoldResult LLVM::AddrSpaceCastOp::fold(FoldAdaptor adaptor) {
   return foldChainableCast(*this, adaptor);
 }
 
+Value LLVM::AddrSpaceCastOp::getViewSource() { return getArg(); }
+
 //===----------------------------------------------------------------------===//
 // Folder for LLVM::GEPOp
 //===----------------------------------------------------------------------===//
@@ -3276,6 +3278,8 @@ OpFoldResult LLVM::GEPOp::fold(FoldAdaptor adaptor) {
   return {};
 }
 
+Value LLVM::GEPOp::getViewSource() { return getBase(); }
+
 //===----------------------------------------------------------------------===//
 // ShlOp
 //===----------------------------------------------------------------------===//

mlir/lib/Dialect/LLVMIR/Transforms/InlinerInterfaceImpl.cpp

@@ -16,6 +16,7 @@
 #include "mlir/Dialect/LLVMIR/LLVMDialect.h"
 #include "mlir/IR/Matchers.h"
 #include "mlir/Interfaces/DataLayoutInterfaces.h"
+#include "mlir/Interfaces/ViewLikeInterface.h"
 #include "mlir/Transforms/InliningUtils.h"
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/Support/Debug.h"
@@ -229,11 +230,10 @@ static FailureOr<SmallVector<Value>>
 getUnderlyingObjectSet(Value pointerValue) {
   SmallVector<Value> result;
   WalkContinuation walkResult = walkSlice(pointerValue, [&](Value val) {
-    if (auto gepOp = val.getDefiningOp<LLVM::GEPOp>())
-      return WalkContinuation::advanceTo(gepOp.getBase());
-
-    if (auto addrCast = val.getDefiningOp<LLVM::AddrSpaceCastOp>())
-      return WalkContinuation::advanceTo(addrCast.getOperand());
+    // Attempt to advance to the source of the underlying view-like operation.
+    // Examples of view-like operations include GEPOp and AddrSpaceCastOp.
+    if (auto viewOp = val.getDefiningOp<ViewLikeOpInterface>())
+      return WalkContinuation::advanceTo(viewOp.getViewSource());
 
     // Attempt to advance to control flow predecessors.
     std::optional<SmallVector<Value>> controlFlowPredecessors =