[CIR] Add back verification of LoopOpInterface (llvm#1641)

The verification used to require a runtime type query of `ConditionOp`
which is not available outside the interface package; whereas the
dialect package depends on the interface package, causing a circular
dependency. This commit adds a singleton interface for `ConditionOp` to
break off the circular dependency, and replaces the runtime type query
using the newly added interface.

Tested locally with a build with shared library enabled and verified
that the build succeeds.

Author: fangyi-zhou

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -872,11 +872,10 @@ def SelectOp : CIR_Op<"select", [Pure,
 // ConditionOp
 //===----------------------------------------------------------------------===//
 
-def ConditionOp : CIR_Op<"condition", [
-  Terminator,
-  DeclareOpInterfaceMethods<RegionBranchTerminatorOpInterface,
-                            ["getSuccessorRegions"]>
-]> {
+def ConditionOp : CIR_Op<"condition", [Terminator, CIR_ConditionOpInterface,
+                                       DeclareOpInterfaceMethods<
+                                           RegionBranchTerminatorOpInterface,
+                                           ["getSuccessorRegions"]>]> {
   let summary = "Loop continuation condition.";
   let description = [{
     The `cir.condition` terminates conditional regions. It takes a single
@@ -2195,10 +2194,8 @@ def BrCondOp : CIR_Op<"brcond",
 // While & DoWhileOp
 //===----------------------------------------------------------------------===//
 
-class WhileOpBase<string mnemonic> : CIR_Op<mnemonic, [
-  LoopOpInterface,
-  NoRegionArguments,
-]> {
+class WhileOpBase<string mnemonic>
+    : CIR_Op<mnemonic, [CIR_LoopOpInterface, NoRegionArguments, ]> {
   defvar isWhile = !eq(mnemonic, "while");
   let summary = "C/C++ " # !if(isWhile, "while", "do-while") # " loop";
   let builders = [
@@ -2273,7 +2270,7 @@ def DoWhileOp : WhileOpBase<"do"> {
 // ForOp
 //===----------------------------------------------------------------------===//
 
-def ForOp : CIR_Op<"for", [LoopOpInterface, NoRegionArguments]> {
+def ForOp : CIR_Op<"for", [CIR_LoopOpInterface, NoRegionArguments]> {
   let summary = "C/C++ for loop counterpart";
   let description = [{
     Represents a C/C++ for loop. It consists of three regions:

clang/include/clang/CIR/Interfaces/CIRLoopOpInterface.td

@@ -13,10 +13,10 @@ include "mlir/IR/OpBase.td"
 include "mlir/Interfaces/ControlFlowInterfaces.td"
 include "mlir/Interfaces/LoopLikeInterface.td"
 
-def LoopOpInterface : OpInterface<"LoopOpInterface", [
-  DeclareOpInterfaceMethods<RegionBranchOpInterface>,
-  DeclareOpInterfaceMethods<LoopLikeOpInterface>
-]> {
+def CIR_LoopOpInterface
+    : OpInterface<"LoopOpInterface",
+                  [DeclareOpInterfaceMethods<RegionBranchOpInterface>,
+                   DeclareOpInterfaceMethods<LoopLikeOpInterface>]> {
   let description = [{
     Contains helper functions to query properties and perform transformations
     on a loop.
@@ -96,4 +96,12 @@ def LoopOpInterface : OpInterface<"LoopOpInterface", [
   }];
 }
 
+def CIR_ConditionOpInterface : OpInterface<"ConditionOpInterface", []> {
+  let description = [{
+    A singleton interface for ConditionOp only. This is used to break off a
+    a dependency from LoopOpInterface onto ConditionOp.
+  }];
+  let cppNamespace = "::cir";
+}
+
 #endif // CLANG_CIR_INTERFACES_CIRLOOPOPINTERFACE

clang/lib/CIR/Interfaces/CIRLoopOpInterface.cpp

@@ -44,11 +44,10 @@ void LoopOpInterface::getLoopOpSuccessorRegions(
 
 /// Verify invariants of the LoopOpInterface.
 llvm::LogicalResult detail::verifyLoopOpInterface(mlir::Operation *op) {
-  // FIXME: fix this so the conditionop isn't requiring MLIRCIR
-  // auto loopOp = mlir::cast<LoopOpInterface>(op);
-  // if (!mlir::isa<ConditionOp>(loopOp.getCond().back().getTerminator()))
-  //   return op->emitOpError(
-  //       "expected condition region to terminate with 'cir.condition'");
+  auto loopOp = mlir::cast<LoopOpInterface>(op);
+  if (!mlir::isa<ConditionOpInterface>(loopOp.getCond().back().getTerminator()))
+    return op->emitOpError(
+        "expected condition region to terminate with 'cir.condition'");
   return llvm::success();
 }
 

clang/test/CIR/IR/invalid.cir

@@ -1533,3 +1533,44 @@ cir.global external dsolocal @vfp = #cir.ptr<null> : !cir.ptr<!cir.func<(!s32i)
 
 // expected-error @below {{integer or floating point type}}
 !complex = !cir.complex<!cir.ptr<!cir.void>>
+
+// -----
+
+#false = #cir.bool<false> : !cir.bool
+#true = #cir.bool<true> : !cir.bool
+cir.func @b0() {
+  cir.scope {
+    cir.while {  // expected-error {{expected condition region to terminate with 'cir.condition'}}
+      cir.yield
+    } do {
+      cir.br ^bb1
+    ^bb1:
+      cir.return
+    }
+  }
+  cir.return
+}
+
+// -----
+
+cir.func @invalid_cond_region_terminator(%arg0 : !cir.bool) -> !cir.void {
+  cir.do { // expected-error {{op expected condition region to terminate with 'cir.condition'}}
+    cir.yield
+  } while {
+    cir.yield
+  }
+  cir.return
+}
+
+// -----
+
+cir.func @invalidConditionTerminator (%arg0 : !cir.bool) -> !cir.void {
+  cir.for : cond { // expected-error {{op expected condition region to terminate with 'cir.condition'}}
+    cir.yield
+  } body {
+    cir.yield
+  } step {
+    cir.yield
+  }
+  cir.return
+}