[MLIR][LLVM] Remove the type consistency pass (#93283)

This commit removes the LLVM dialect's type consistency pass. This pass
was originally introduced to make type information on memory operations
consistent. The main benefactor of this consistency where Mem2Reg and
SROA, which were in the meantime improved to no longer require
consistent type information.

Apart from providing a no longer required functionality, the pass had
some fundamental flaws that lead to issues:
* It introduced trivial GEPs (only zero indices) that could be folded
again.
* Aggressively splitting stores lead to substantial performance
regressions in some cases. Subsequent memory coalescing were not able to
recover this information, due to using non-trivial bit-fiddling.

Author: Dinistro

mlir/include/mlir/Dialect/LLVMIR/Transforms/Passes.h

@@ -13,7 +13,6 @@
 #include "mlir/Dialect/LLVMIR/Transforms/LegalizeForExport.h"
 #include "mlir/Dialect/LLVMIR/Transforms/OptimizeForNVVM.h"
 #include "mlir/Dialect/LLVMIR/Transforms/RequestCWrappers.h"
-#include "mlir/Dialect/LLVMIR/Transforms/TypeConsistency.h"
 #include "mlir/Pass/Pass.h"
 
 namespace mlir {

mlir/include/mlir/Dialect/LLVMIR/Transforms/Passes.td

@@ -43,24 +43,6 @@ def LLVMRequestCWrappers
   let constructor = "::mlir::LLVM::createRequestCWrappersPass()";
 }
 
-def LLVMTypeConsistency
-    : Pass<"llvm-type-consistency", "::mlir::LLVM::LLVMFuncOp"> {
-  let summary = "Rewrites to improve type consistency";
-  let description = [{
-    Set of rewrites to improve the coherency of types within an LLVM dialect
-    program. This will adjust operations operating on pointers so they interpret
-    their associated pointee type as consistently as possible.
-  }];
-  let constructor = "::mlir::LLVM::createTypeConsistencyPass()";
-
-  let options = [
-    Option<"maxVectorSplitSize", "max-vector-split-size", "unsigned",
-           /*default=*/"512",
-           "Maximum size in bits of a vector value in a load or store operation"
-           " operating on multiple elements that should still be split">,
-  ];
-}
-
 def NVVMOptimizeForTarget : Pass<"llvm-optimize-for-nvvm-target"> {
   let summary = "Optimize NVVM IR";
   let constructor = "::mlir::NVVM::createOptimizeForTargetPass()";

mlir/include/mlir/Dialect/LLVMIR/Transforms/TypeConsistency.h

@@ -6,7 +6,6 @@ add_mlir_dialect_library(MLIRLLVMIRTransforms
   LegalizeForExport.cpp
   OptimizeForNVVM.cpp
   RequestCWrappers.cpp
-  TypeConsistency.cpp
 
   DEPENDS
   MLIRLLVMPassIncGen