Separate translators into "from MLIR" and "to MLIR".

Translations performed by mlir-translate only have MLIR on one end.
MLIR-to-MLIR conversions (including dialect changes) should be treated as
passes and run by mlir-opt.  Individual translations should not care about
reading or writing MLIR and should work on in-memory representation of MLIR
modules instead.  Split the TranslateFunction interface and the translate
registry into two parts: "from MLIR" and "to MLIR".

Update mlir-translate to handle both registries together by wrapping
translation functions into source-to-source convresions.  Remove MLIR parsing
and writing from individual translations and make them operate on Modules
instead.  This removes the need for individual translators to include
tools/mlir-translate/mlir-translate.h, which can now be safely removed.

Remove mlir-to-mlir translation that only existed as a registration example and
use mlir-opt instead for tests.

PiperOrigin-RevId: 222398707

1 files changed, 40 insertions, 14 deletions

diff --git a/mlir/lib/Translation/Translation.cpp b/mlir/lib/Translation/Translation.cpp
index 96765c71b81..c1a9f9d11fc 100644
--- a/mlir/lib/Translation/Translation.cpp
+++ b/mlir/lib/Translation/Translation.cpp
@@ -25,24 +25,50 @@
 
 using namespace mlir;
 
-// Get the mutable static map between translations registered and the
-// TranslateFunctions that perform those translations.
-static llvm::StringMap<TranslateFunction> &getMutableTranslationRegistry() {
-  static llvm::StringMap<TranslateFunction> translationRegistry;
-  return translationRegistry;
+// Get the mutable static map between registered "to MLIR" translations and the
+// TranslateToMLIRFunctions that perform those translations.
+static llvm::StringMap<TranslateToMLIRFunction> &
+getMutableTranslationToMLIRRegistry() {
+  static llvm::StringMap<TranslateToMLIRFunction> translationToMLIRRegistry;
+  return translationToMLIRRegistry;
+}
+// Get the mutable static map between registered "from MLIR" translations and
+// the TranslateFromMLIRFunctions that perform those translations.
+static llvm::StringMap<TranslateFromMLIRFunction> &
+getMutableTranslationFromMLIRRegistry() {
+  static llvm::StringMap<TranslateFromMLIRFunction> translationFromMLIRRegistry;
+  return translationFromMLIRRegistry;
+}
+
+TranslateToMLIRRegistration::TranslateToMLIRRegistration(
+    StringRef name, const TranslateToMLIRFunction &function) {
+  auto &translationToMLIRRegistry = getMutableTranslationToMLIRRegistry();
+  if (translationToMLIRRegistry.find(name) != translationToMLIRRegistry.end())
+    llvm::report_fatal_error(
+        "Attempting to overwrite an existing <to> function");
+  assert(function && "Attempting to register an empty translate <to> function");
+  translationToMLIRRegistry[name] = function;
 }
 
-TranslateRegistration::TranslateRegistration(
-    StringRef name, const TranslateFunction &function) {
-  auto &translationRegistry = getMutableTranslationRegistry();
-  if (translationRegistry.find(name) != translationRegistry.end())
-    llvm::report_fatal_error("Attempting to overwrite an existing function");
-  assert(function && "Attempting to register an empty translate function");
-  translationRegistry[name] = function;
+TranslateFromMLIRRegistration::TranslateFromMLIRRegistration(
+    StringRef name, const TranslateFromMLIRFunction &function) {
+  auto &translationFromMLIRRegistry = getMutableTranslationFromMLIRRegistry();
+  if (translationFromMLIRRegistry.find(name) !=
+      translationFromMLIRRegistry.end())
+    llvm::report_fatal_error(
+        "Attempting to overwrite an existing <from> function");
+  assert(function && "Attempting to register an empty translate <to> function");
+  translationFromMLIRRegistry[name] = function;
 }
 
 // Merely add the const qualifier to the mutable registry so that external users
 // cannot modify it.
-const llvm::StringMap<TranslateFunction> &mlir::getTranslationRegistry() {
-  return getMutableTranslationRegistry();
+const llvm::StringMap<TranslateToMLIRFunction> &
+mlir::getTranslationToMLIRRegistry() {
+  return getMutableTranslationToMLIRRegistry();
+}
+
+const llvm::StringMap<TranslateFromMLIRFunction> &
+mlir::getTranslationFromMLIRRegistry() {
+  return getMutableTranslationFromMLIRRegistry();
 }