[mlir] Remove loop peeling explicit C'tor (#175419)

The SCF dialect loop peeling pass has an explicit C'tor. This creates an
inconvenience to use non default pass options, since they can only be
passed as a string after the pass creation. After removing the explicit
C'tor, the code auto generation creates 2 C'tors, which one of them can
directly receive pass options struct in case non default values are
required.
The explicit C'tor does not match auto generated C'tor convention, so
this change requires any uses of the pass in downstream projects to
update to use the auto generated C'tor.

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

diff --git a/mlir/include/mlir/Dialect/SCF/Transforms/Passes.h b/mlir/include/mlir/Dialect/SCF/Transforms/Passes.h
index 54b0118..e5794db 100644
--- a/mlir/include/mlir/Dialect/SCF/Transforms/Passes.h
+++ b/mlir/include/mlir/Dialect/SCF/Transforms/Passes.h
@@ -24,10 +24,6 @@
 /// vectorization.
 std::unique_ptr<Pass> createForLoopSpecializationPass();
 
-/// Creates a pass that peels for loops at their upper bounds for
-/// better vectorization.
-std::unique_ptr<Pass> createForLoopPeelingPass();
-
 /// Creates a pass that canonicalizes affine.min and affine.max operations
 /// inside of scf.for loops with known lower and upper bounds.
 std::unique_ptr<Pass> createSCFForLoopCanonicalizationPass();

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

diff --git a/mlir/include/mlir/Dialect/SCF/Transforms/Passes.td b/mlir/include/mlir/Dialect/SCF/Transforms/Passes.td
index 3ac651f..44e523f 100644
--- a/mlir/include/mlir/Dialect/SCF/Transforms/Passes.td
+++ b/mlir/include/mlir/Dialect/SCF/Transforms/Passes.td
@@ -23,7 +23,6 @@
 
 def SCFForLoopPeeling : Pass<"scf-for-loop-peeling"> {
   let summary = "Peel `for` loops at their upper bounds.";
-  let constructor = "mlir::createForLoopPeelingPass()";
   let options = [
     Option<"peelFront", "peel-front", "bool",
            /*default=*/"false",

mlir/lib/Dialect/SCF/Transforms/LoopSpecialization.cpp

diff --git a/mlir/lib/Dialect/SCF/Transforms/LoopSpecialization.cpp b/mlir/lib/Dialect/SCF/Transforms/LoopSpecialization.cpp
index c7588b4..cff01d1 100644
--- a/mlir/lib/Dialect/SCF/Transforms/LoopSpecialization.cpp
+++ b/mlir/lib/Dialect/SCF/Transforms/LoopSpecialization.cpp
@@ -337,6 +337,8 @@
 };
 
 struct ForLoopPeeling : public impl::SCFForLoopPeelingBase<ForLoopPeeling> {
+  using impl::SCFForLoopPeelingBase<ForLoopPeeling>::SCFForLoopPeelingBase;
+
   void runOnOperation() override {
     auto *parentOp = getOperation();
     MLIRContext *ctx = parentOp->getContext();
@@ -360,7 +362,3 @@
 std::unique_ptr<Pass> mlir::createForLoopSpecializationPass() {
   return std::make_unique<ForLoopSpecialization>();
 }
-
-std::unique_ptr<Pass> mlir::createForLoopPeelingPass() {
-  return std::make_unique<ForLoopPeeling>();
-}