[GlobalOpt] Reimplement softmax matcher natively (#24466)

Replace the wholesale relocation of the iree-dialects TransformMatchers
DSL with a self-contained, native matcher in RaiseSpecialOps.cpp, per the
review feedback that this should port only what RaiseSpecialOps needs
rather than carry the generic StructuredOpMatcher framework into
GlobalOptimization.

- Add a local matchSoftmax() plus small helpers that walk the softmax
  linalg-op graph directly (reduce_max -> sub -> exp -> reduce_add ->
  mul/reciprocal or div), handling both implicit (projected map) and
  explicit (pass-through generic) broadcasts. This is behaviorally
  faithful to makeSoftmaxMatcher, including the same-source invariant.
- Delete GlobalOptimization/TransformMatchers.{h,cpp} (~3000 lines) and
  drop the transform-dialect build deps that only existed for them. The
  iree-dialects deps stay removed.
- Add negative lit cases (wrong max init, mismatched source) alongside
  the existing softmax raising tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Han || Alex <36247722+Alex-Wengg@users.noreply.github.com>

Author: Alex-Wengg

compiler/src/iree/compiler/GlobalOptimization/BUILD.bazel

@@ -71,13 +71,11 @@ iree_compiler_cc_library(
         "RaiseSpecialOps.cpp",
         "RemoveZeroExtentTensors.cpp",
         "SimplifyPackUnpack.cpp",
-        "TransformMatchers.cpp",
         "Utils.cpp",
         "WarnOnUninitializedValues.cpp",
     ],
     hdrs = [
         "Passes.h",
-        "TransformMatchers.h",
         "Utils.h",
     ],
     deps = [
@@ -107,31 +105,25 @@ iree_compiler_cc_library(
         "//compiler/src/iree/compiler/Utils",
         "@llvm-project//llvm:Support",
         "@llvm-project//mlir:AffineDialect",
-        "@llvm-project//mlir:Analysis",
         "@llvm-project//mlir:ArithDialect",
         "@llvm-project//mlir:ArithUtils",
         "@llvm-project//mlir:ControlFlowDialect",
         "@llvm-project//mlir:DialectUtils",
-        "@llvm-project//mlir:FuncDialect",
         "@llvm-project//mlir:FunctionInterfaces",
         "@llvm-project//mlir:IR",
         "@llvm-project//mlir:LinalgDialect",
-        "@llvm-project//mlir:LinalgInterfaces",
         "@llvm-project//mlir:LinalgTransforms",
         "@llvm-project//mlir:LinalgUtils",
         "@llvm-project//mlir:MathDialect",
         "@llvm-project//mlir:MemRefDialect",
         "@llvm-project//mlir:MemRefTransforms",
         "@llvm-project//mlir:Pass",
-        "@llvm-project//mlir:Rewrite",
         "@llvm-project//mlir:SCFDialect",
         "@llvm-project//mlir:SCFTransforms",
         "@llvm-project//mlir:Support",
         "@llvm-project//mlir:TensorDialect",
         "@llvm-project//mlir:TensorTransforms",
         "@llvm-project//mlir:TensorUtils",
-        "@llvm-project//mlir:TransformDialect",
-        "@llvm-project//mlir:TransformDialectInterfaces",
         "@llvm-project//mlir:TransformUtils",
         "@llvm-project//mlir:Transforms",
     ],

compiler/src/iree/compiler/GlobalOptimization/CMakeLists.txt

@@ -38,7 +38,6 @@ iree_cc_library(
     GlobalOptimization
   HDRS
     "Passes.h"
-    "TransformMatchers.h"
     "Utils.h"
   SRCS
     "CleanupNumericNarrowing.cpp"
@@ -63,38 +62,31 @@ iree_cc_library(
     "RaiseSpecialOps.cpp"
     "RemoveZeroExtentTensors.cpp"
     "SimplifyPackUnpack.cpp"
-    "TransformMatchers.cpp"
     "Utils.cpp"
     "WarnOnUninitializedValues.cpp"
   DEPS
     ::PassHeaders
     ::PassesIncGen
     LLVMSupport
     MLIRAffineDialect
-    MLIRAnalysis
     MLIRArithDialect
     MLIRArithUtils
     MLIRControlFlowDialect
-    MLIRFuncDialect
     MLIRFunctionInterfaces
     MLIRIR
     MLIRLinalgDialect
-    MLIRLinalgInterfacesIncGenLib
     MLIRLinalgTransforms
     MLIRLinalgUtils
     MLIRMathDialect
     MLIRMemRefDialect
     MLIRMemRefTransforms
     MLIRPass
-    MLIRRewrite
     MLIRSCFDialect
     MLIRSCFTransforms
     MLIRSupport
     MLIRTensorDialect
     MLIRTensorTransforms
     MLIRTensorUtils
-    MLIRTransformDialect
-    MLIRTransformDialectInterfaces
     MLIRTransformUtils
     MLIRTransforms
     iree::compiler::Codegen::Common