[flang-commits] [flang] [flang][FIR] implement asm alias interface for fir.type under option (PR #208665)

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<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-flang-fir-hlfir

Author: jeanPerier

<details>
<summary>Changes</summary>

FIR is extremely verbose with derived types because the type lists all the component names and types, so in case of nested derived type, the type length in the assembly may grow over thousands of characters.

This patch implements the  `getAlias` that allows using the fir.type name as the MLIR type alias. This significantly reduce the IR size in application with derived type.

I am planning to enable this by default, but there will be some churn in the lit test, so I am first adding it under a developer option.

Assisted-by: Cursor

---
Full diff: https://github.com/llvm/llvm-project/pull/208665.diff


3 Files Affected:

- (modified) flang/include/flang/Optimizer/Dialect/FIRTypes.td (+4-1) 
- (modified) flang/lib/Optimizer/Dialect/FIRType.cpp (+20-2) 
- (added) flang/test/Fir/derived-type-aliases.fir (+24) 


``````````diff
diff --git a/flang/include/flang/Optimizer/Dialect/FIRTypes.td b/flang/include/flang/Optimizer/Dialect/FIRTypes.td
index 1d66507a23545..cc6b92f5171e2 100644
--- a/flang/include/flang/Optimizer/Dialect/FIRTypes.td
+++ b/flang/include/flang/Optimizer/Dialect/FIRTypes.td
@@ -15,6 +15,7 @@
 
 include "mlir/IR/AttrTypeBase.td"
 include "mlir/IR/BuiltinTypeInterfaces.td"
+include "mlir/IR/OpAsmInterface.td"
 include "flang/Optimizer/Dialect/FIRDialect.td"
 
 //===----------------------------------------------------------------------===//
@@ -316,7 +317,9 @@ def fir_PointerType : FIR_Type<"Pointer", "ptr"> {
   }];
 }
 
-def fir_RecordType : FIR_Type<"Record", "type", [MemRefElementTypeInterface]> {
+def fir_RecordType : FIR_Type<"Record", "type",
+    [DeclareTypeInterfaceMethods<OpAsmTypeInterface, ["getAlias"]>,
+     MemRefElementTypeInterface]> {
   let summary = "FIR derived type";
 
   let description = [{
diff --git a/flang/lib/Optimizer/Dialect/FIRType.cpp b/flang/lib/Optimizer/Dialect/FIRType.cpp
index 6eaecc69fe742..178860239e17d 100644
--- a/flang/lib/Optimizer/Dialect/FIRType.cpp
+++ b/flang/lib/Optimizer/Dialect/FIRType.cpp
@@ -24,6 +24,7 @@
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/TypeSwitch.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
 
 #define GET_TYPEDEF_CLASSES
@@ -31,6 +32,11 @@
 
 using namespace fir;
 
+static llvm::cl::opt<bool> enableFirTypeAliases(
+    "enable-fir-type-aliases",
+    llvm::cl::desc("Enable MLIR type aliases for FIR derived types"),
+    llvm::cl::init(false), llvm::cl::Hidden);
+
 namespace {
 
 template <typename TYPE>
@@ -1122,7 +1128,7 @@ void fir::RecordType::print(mlir::AsmPrinter &printer) const {
       char ch = '(';
       for (auto p : getLenParamList()) {
         printer << ch << p.first << ':';
-        p.second.print(printer.getStream());
+        printer.printType(p.second);
         ch = ',';
       }
       printer << ')';
@@ -1134,7 +1140,7 @@ void fir::RecordType::print(mlir::AsmPrinter &printer) const {
       char ch = '{';
       for (auto p : getTypeList()) {
         printer << ch << p.first << ':';
-        p.second.print(printer.getStream());
+        printer.printType(p.second);
         ch = ',';
       }
       printer << '}';
@@ -1147,6 +1153,18 @@ void fir::RecordType::print(mlir::AsmPrinter &printer) const {
   printer << '>';
 }
 
+mlir::OpAsmAliasResult fir::RecordType::getAlias(llvm::raw_ostream &os) const {
+  if (!enableFirTypeAliases)
+    return mlir::OpAsmAliasResult::NoAlias;
+  // Derived type names may contain "." that are forbidden in MLIR type
+  // alias. Replace them by a capital 'X' that cannot be found in user
+  // defined derived type and is also used as a replacement before generating
+  // llvm assembly.
+  for (char ch : getName())
+    os << (ch == '.' ? 'X' : ch);
+  return mlir::OpAsmAliasResult::OverridableAlias;
+}
+
 void fir::RecordType::finalize(llvm::ArrayRef<TypePair> lenPList,
                                llvm::ArrayRef<TypePair> typeList) {
   getImpl()->finalize(lenPList, typeList);
diff --git a/flang/test/Fir/derived-type-aliases.fir b/flang/test/Fir/derived-type-aliases.fir
new file mode 100644
index 0000000000000..b2495213e4c56
--- /dev/null
+++ b/flang/test/Fir/derived-type-aliases.fir
@@ -0,0 +1,24 @@
+// RUN: fir-opt %s | FileCheck %s --check-prefix=DEFAULT
+// RUN: fir-opt -enable-fir-type-aliases %s | FileCheck %s --check-prefix=ALIASES
+
+module {
+  func.func @use_aliases(
+      %arg0: !fir.ref<!fir.type<outer{inner:!fir.type<inner{p:!fir.box<!fir.ptr<f32>>}>}>>,
+      %arg1: !fir.ref<!fir.type<a.b{x:i32}>>,
+      %arg2: !fir.ref<!fir.type<a_b{x:i64}>>,
+      %arg3: !fir.ref<!fir.type<recursive{next:!fir.box<!fir.heap<!fir.type<recursive>>>}>>) {
+    return
+  }
+}
+
+// DEFAULT-NOT: !outer =
+// DEFAULT-NOT: !aXb =
+// DEFAULT-NOT: !a_b =
+// DEFAULT: func.func @use_aliases(%{{.*}}: !fir.ref<!fir.type<outer{inner:!fir.type<inner{p:!fir.box<!fir.ptr<f32>>}>}>>, %{{.*}}: !fir.ref<!fir.type<a.b{x:i32}>>, %{{.*}}: !fir.ref<!fir.type<a_b{x:i64}>>, %{{.*}}: !fir.ref<!fir.type<recursive{next:!fir.box<!fir.heap<!fir.type<recursive>>>}>>)
+
+// ALIASES-DAG: !aXb = !fir.type<a.b{x:i32}>
+// ALIASES-DAG: !a_b = !fir.type<a_b{x:i64}>
+// ALIASES-DAG: !inner = !fir.type<inner{p:!fir.box<!fir.ptr<f32>>}>
+// ALIASES-DAG: !outer = !fir.type<outer{inner:!inner}>
+// ALIASES-DAG: !recursive = !fir.type<recursive{next:!fir.box<!fir.heap<!fir.type<recursive>>>}>
+// ALIASES: func.func @use_aliases(%{{.*}}: !fir.ref<!outer>, %{{.*}}: !fir.ref<!aXb>, %{{.*}}: !fir.ref<!a_b>, %{{.*}}: !fir.ref<!recursive>)

``````````

</details>


https://github.com/llvm/llvm-project/pull/208665