refactor(compiler): Introduce compilation pipeline with multiple entries / exits

This refactoring commit restructures the compilation pipeline of
`zamacompiler`, such that it is possible to enter and exit the
pipeline at different points, effectively defining the level of
abstraction at the input and the required level of abstraction for the
output.

The entry point is specified using the `--entry-dialect`
argument. Valid choices are:

  `--entry-dialect=hlfhe`:   Source contains HLFHE operations
  `--entry-dialect=midlfhe`: Source contains MidLFHE operations
  `--entry-dialect=lowlfhe`: Source contains LowLFHE operations
  `--entry-dialect=std`:     Source does not contain any FHE Operations
  `--entry-dialect=llvm`:    Source is in LLVM dialect

The exit point is defined by an action, specified using --action.

  `--action=roundtrip`:
     Parse the source file to in-memory representation and immediately
     dump as text without any processing

  `--action=dump-midlfhe`:
     Lower source to MidLFHE and dump result as text

  `--action=dump-lowlfhe`:
     Lower source to LowLFHE and dump result as text

  `--action=dump-std`:
     Lower source to only standard MLIR dialects (i.e., all FHE
     operations have already been lowered)

  `--action=dump-llvm-dialect`:
     Lower source to MLIR's LLVM dialect (i.e., the LLVM dialect, not
     LLVM IR)

  `--action=dump-llvm-ir`:
     Lower source to plain LLVM IR (i.e., not the LLVM dialect, but
     actual LLVM IR)

  `--action=dump-optimized-llvm-ir`:
     Lower source to plain LLVM IR (i.e., not the LLVM dialect, but
     actual LLVM IR), pass the result through the LLVM optimizer and
     print the result.

  `--action=dump-jit-invoke`:
     Execute the full lowering pipeline to optimized LLVM IR, JIT
     compile the result, invoke the function specified in
     `--jit-funcname` with the parameters from `--jit-args` and print
     the functions return value.

compiler/lib/Support/CompilerEngine.cpp

@@ -1,8 +1,16 @@
-#include "zamalang/Support/CompilerEngine.h"
-#include "zamalang/Conversion/Passes.h"
+#include <mlir/Dialect/LLVMIR/LLVMDialect.h>
+#include <mlir/Dialect/Linalg/IR/LinalgOps.h>
+#include <mlir/Dialect/MemRef/IR/MemRef.h>
+#include <mlir/Dialect/StandardOps/IR/Ops.h>
 #include <mlir/ExecutionEngine/OptUtils.h>
 #include <mlir/Parser.h>
 
+#include <zamalang/Dialect/HLFHE/IR/HLFHEDialect.h>
+#include <zamalang/Dialect/LowLFHE/IR/LowLFHEDialect.h>
+#include <zamalang/Dialect/MidLFHE/IR/MidLFHEDialect.h>
+#include <zamalang/Support/CompilerEngine.h>
+#include <zamalang/Support/Pipeline.h>
+
 namespace mlir {
 namespace zamalang {
 
@@ -29,10 +37,20 @@ llvm::Error CompilerEngine::compile(std::string mlirStr) {
     return llvm::make_error<llvm::StringError>("mlir parsing failed",
                                                llvm::inconvertibleErrorCode());
   }
-  mlir::zamalang::V0FHEContext fheContext;
+
+  mlir::zamalang::V0FHEConstraint defaultGlobalFHECircuitConstraint{.norm2 = 10,
+                                                                    .p = 7};
+  const mlir::zamalang::V0Parameter *parameter =
+      getV0Parameter(defaultGlobalFHECircuitConstraint);
+
+  mlir::zamalang::V0FHEContext fheContext{defaultGlobalFHECircuitConstraint,
+                                          *parameter};
+
+  mlir::ModuleOp module = module_ref.get();
+
   // Lower to MLIR Std
-  if (mlir::zamalang::CompilerTools::lowerHLFHEToMlirStdsDialect(
-          *context, module_ref.get(), fheContext)
+  if (mlir::zamalang::pipeline::lowerHLFHEToStd(*context, module, fheContext,
+                                                false)
           .failed()) {
     return llvm::make_error<llvm::StringError>("failed to lower to MLIR Std",
                                                llvm::inconvertibleErrorCode());
@@ -53,8 +71,7 @@ llvm::Error CompilerEngine::compile(std::string mlirStr) {
   keySet = std::move(maybeKeySet.get());
 
   // Lower to MLIR LLVM Dialect
-  if (mlir::zamalang::CompilerTools::lowerMlirStdsDialectToMlirLLVMDialect(
-          *context, module_ref.get())
+  if (mlir::zamalang::pipeline::lowerStdToLLVMDialect(*context, module, false)
           .failed()) {
     return llvm::make_error<llvm::StringError>(
         "failed to lower to LLVM dialect", llvm::inconvertibleErrorCode());
@@ -114,4 +131,4 @@ llvm::Expected<uint64_t> CompilerEngine::run(std::vector<uint64_t> args) {
   return res;
 }
 } // namespace zamalang
-} // namespace mlir
+} // namespace mlir