[Mlir-commits] [mlir] [mlir-tblgen] trim method body to empty with only spaces to avoid crash (PR #139568)

[llvmlistbot at llvm.org]

https://github.com/fengxie created https://github.com/llvm/llvm-project/pull/139568

method body or default impl must be true empty. Even they contain only spaces, ``mlir-tblgen`` considers they are non-empty and generates invalid code lead to segment fault. It's very hard to debug.

```c++
    InterfaceMethod<
      ...
      /*methodBody=*/  [{ }],    // This must be true empty. Leaving a space here can lead to segment fault which is hard to figure out why
      /*defaultImpl=*/ [{
        ...
      }]
```

This PR trim spaces when method body or default implementation of interface method is not empty. Now ``mlir-tblgen`` generates valid code even when they contain only spaces.

>From 1dfa667491a0b6249685779b6fb3835255266c31 Mon Sep 17 00:00:00 2001
From: Fung Xie <ftse at nvidia.com>
Date: Mon, 12 May 2025 23:27:57 +0800
Subject: [PATCH 1/2] trim method body with spaces to avoid crash

---
 mlir/lib/TableGen/Interfaces.cpp              |  6 +++
 .../mlir-tblgen/method-body-has-spaces.td     | 45 +++++++++++++++++++
 2 files changed, 51 insertions(+)
 create mode 100644 mlir/test/mlir-tblgen/method-body-has-spaces.td

diff --git a/mlir/lib/TableGen/Interfaces.cpp b/mlir/lib/TableGen/Interfaces.cpp
index a209b003b0f3b..9e9d4e4d3b13a 100644
--- a/mlir/lib/TableGen/Interfaces.cpp
+++ b/mlir/lib/TableGen/Interfaces.cpp
@@ -47,12 +47,18 @@ bool InterfaceMethod::isStatic() const {
 // Return the body for this method if it has one.
 std::optional<StringRef> InterfaceMethod::getBody() const {
   auto value = def->getValueAsString("body");
+  // Trim leading and trailing spaces from the default implementation.
+  if (!value.empty())
+    value = value.trim();
   return value.empty() ? std::optional<StringRef>() : value;
 }
 
 // Return the default implementation for this method if it has one.
 std::optional<StringRef> InterfaceMethod::getDefaultImplementation() const {
   auto value = def->getValueAsString("defaultBody");
+  // Trim leading and trailing spaces from the default implementation.
+  if (!value.empty())
+    value = value.trim();
   return value.empty() ? std::optional<StringRef>() : value;
 }
 
diff --git a/mlir/test/mlir-tblgen/method-body-has-spaces.td b/mlir/test/mlir-tblgen/method-body-has-spaces.td
new file mode 100644
index 0000000000000..41ff84e9b480a
--- /dev/null
+++ b/mlir/test/mlir-tblgen/method-body-has-spaces.td
@@ -0,0 +1,45 @@
+// RUN: mlir-tblgen -gen-op-defs -I %S/../../include %s | FileCheck %s
+
+include "mlir/IR/OpBase.td"
+
+def TestEmptyMethodBodyTypeInterface : TypeInterface<"TestEmptyMethodBodyTypeInterface"> {
+  let cppNamespace = "::TestEmptyMethodBodyTypeInterface";
+  let description = [{
+    Treat method body with only spaces as empty.
+  }];
+  let methods = [
+    InterfaceMethod<
+      /*desc=*/        [{ Trim spaces of method body and default implementation }],
+      /*returnType=*/  "StringRef",
+      /*methodName=*/  "trimSpaces",
+      /*args=*/        (ins),
+      // CHECK-LABEL: StringRef detail::TestEmptyMethodBodyTypeInterfaceInterfaceTraits::Model<ConcreteType>::trimSpaces
+      // CHECK-SAME: {
+      // CHECK-NEXT: return (::llvm::cast<ConcreteType>(tablegen_opaque_val)).trimSpaces();
+      // CHECK-NEXT: }
+      /*methodBody=*/  [{  }],
+      /*defaultImpl=*/ [{ return StringRef(); }]
+    >
+  ];
+}
+
+def TestEmptyDefaultImplTypeInterface : TypeInterface<"TestEmptyDefaultImplTypeInterface"> {
+  let cppNamespace = "::TestEmptyDefaultImplTypeInterface";
+  let description = [{
+    Treat default implementation with only spaces as empty.
+  }];
+
+  let methods = [
+    InterfaceMethod<
+      /*desc=*/        [{ Trim spaces of default implementation }],
+      /*returnType=*/  "StringRef",
+      /*methodName=*/  "trimSpaces",
+      /*args=*/        (ins),
+      /*methodBody=*/  [{ return StringRef(); }],
+      // COM: Don't generate default implementation
+      // CHECK-NOT: StringRef detail::TestEmptyDefaultImplTypeInterfaceInterfaceTraits::ExternalModel<ConcreteModel, ConcreteType>::trimSpaces
+      /*defaultImpl=*/ [{
+      }]
+    >
+  ];
+}

>From 7b59fe547301e5c19b81aee8d1401a2c4c0abed5 Mon Sep 17 00:00:00 2001
From: Fung Xie <ftse at nvidia.com>
Date: Mon, 12 May 2025 23:51:27 +0800
Subject: [PATCH 2/2] fix test and rename

---
 ...ethod-body-has-spaces.td => method-body-with-only-spaces.td} | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 rename mlir/test/mlir-tblgen/{method-body-has-spaces.td => method-body-with-only-spaces.td} (94%)

diff --git a/mlir/test/mlir-tblgen/method-body-has-spaces.td b/mlir/test/mlir-tblgen/method-body-with-only-spaces.td
similarity index 94%
rename from mlir/test/mlir-tblgen/method-body-has-spaces.td
rename to mlir/test/mlir-tblgen/method-body-with-only-spaces.td
index 41ff84e9b480a..daa0067e062d5 100644
--- a/mlir/test/mlir-tblgen/method-body-has-spaces.td
+++ b/mlir/test/mlir-tblgen/method-body-with-only-spaces.td
@@ -1,4 +1,4 @@
-// RUN: mlir-tblgen -gen-op-defs -I %S/../../include %s | FileCheck %s
+// RUN: mlir-tblgen --gen-type-interface-decls -I %S/../../include %s | FileCheck %s
 
 include "mlir/IR/OpBase.td"