[MLIR][Shape] Merge shape to std/scf lowerings.

Merge the two lowering passes because they are not useful by themselves. The new
pass lowers to `std` and `scf` is considered an auxiliary dialect.

See also
https://llvm.discourse.group/t/conversions-with-multiple-target-dialects/1541/12

Differential Revision: https://reviews.llvm.org/D86779

Author: frgossen

mlir/include/mlir/Conversion/Passes.h

@@ -23,7 +23,6 @@
 #include "mlir/Conversion/SCFToGPU/SCFToGPUPass.h"
 #include "mlir/Conversion/SCFToStandard/SCFToStandard.h"
 #include "mlir/Conversion/SPIRVToLLVM/ConvertSPIRVToLLVMPass.h"
-#include "mlir/Conversion/ShapeToSCF/ShapeToSCF.h"
 #include "mlir/Conversion/ShapeToStandard/ShapeToStandard.h"
 #include "mlir/Conversion/StandardToLLVM/ConvertStandardToLLVMPass.h"
 #include "mlir/Conversion/StandardToSPIRV/ConvertStandardToSPIRVPass.h"

mlir/include/mlir/Conversion/Passes.td

@@ -239,17 +239,7 @@ def ConvertShapeToStandard : Pass<"convert-shape-to-std", "ModuleOp"> {
   let summary = "Convert operations from the shape dialect into the standard "
                 "dialect";
   let constructor = "mlir::createConvertShapeToStandardPass()";
-  let dependentDialects = ["StandardOpsDialect"];
-}
-
-//===----------------------------------------------------------------------===//
-// ShapeToSCF
-//===----------------------------------------------------------------------===//
-
-def ConvertShapeToSCF : FunctionPass<"convert-shape-to-scf"> {
-  let summary = "Convert operations from the shape dialect to the SCF dialect";
-  let constructor = "mlir::createConvertShapeToSCFPass()";
-  let dependentDialects = ["scf::SCFDialect"];
+  let dependentDialects = ["StandardOpsDialect", "scf::SCFDialect"];
 }
 
 //===----------------------------------------------------------------------===//

mlir/include/mlir/Conversion/ShapeToSCF/ShapeToSCF.h

@@ -12,7 +12,6 @@ add_subdirectory(OpenMPToLLVM)
 add_subdirectory(SCFToGPU)
 add_subdirectory(SCFToSPIRV)
 add_subdirectory(SCFToStandard)
-add_subdirectory(ShapeToSCF)
 add_subdirectory(ShapeToStandard)
 add_subdirectory(SPIRVToLLVM)
 add_subdirectory(StandardToLLVM)