[CIR][NFC] Fix warnings in release builds (llvm#168791)

This fixes several warnings that occur in CIR release builds.

Author: andykaylor

clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp

@@ -292,7 +292,7 @@ emitSuspendExpression(CIRGenFunction &cgf, CGCoroData &coro,
                       AggValueSlot aggSlot, bool ignoreResult,
                       mlir::Block *scopeParentBlock,
                       mlir::Value &tmpResumeRValAddr, bool forLValue) {
-  mlir::LogicalResult awaitBuild = mlir::success();
+  [[maybe_unused]] mlir::LogicalResult awaitBuild = mlir::success();
   LValueOrRValue awaitRes;
 
   CIRGenFunction::OpaqueValueMapping binder =

clang/lib/CIR/CodeGen/CIRGenException.cpp

@@ -425,7 +425,7 @@ void CIRGenFunction::exitCXXTryStmt(const CXXTryStmt &s, bool isFnTryBlock) {
     assert(!cir::MissingFeatures::incrementProfileCounter());
 
     // Perform the body of the catch.
-    mlir::LogicalResult emitResult =
+    [[maybe_unused]] mlir::LogicalResult emitResult =
         emitStmt(catchStmt->getHandlerBlock(), /*useCurrentScope=*/true);
     assert(emitResult.succeeded() && "failed to emit catch handler block");
 

clang/lib/CIR/CodeGen/CIRGenExprCXX.cpp

@@ -426,7 +426,7 @@ static mlir::Value emitCXXNewAllocSize(CIRGenFunction &cgf, const CXXNewExpr *e,
     const llvm::APInt &count =
         mlir::cast<cir::IntAttr>(constNumElements).getValue();
 
-    unsigned numElementsWidth = count.getBitWidth();
+    [[maybe_unused]] unsigned numElementsWidth = count.getBitWidth();
     bool hasAnyOverflow = false;
 
     // The equivalent code in CodeGen/CGExprCXX.cpp handles these cases as

clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp

@@ -459,7 +459,8 @@ void CIRGenItaniumCXXABI::emitVTableDefinitions(CIRGenVTables &cgvt,
                  "emitVTableDefinitions: __fundamental_type_info");
   }
 
-  auto vtableAsGlobalValue = dyn_cast<cir::CIRGlobalValueInterface>(*vtable);
+  [[maybe_unused]] auto vtableAsGlobalValue =
+      dyn_cast<cir::CIRGlobalValueInterface>(*vtable);
   assert(vtableAsGlobalValue && "VTable must support CIRGlobalValueInterface");
   // Always emit type metadata on non-available_externally definitions, and on
   // available_externally definitions if we are performing whole program

clang/lib/CIR/Dialect/Transforms/LoweringPrepare.cpp

@@ -462,7 +462,7 @@ static mlir::Type higherPrecisionElementTypeForComplexArithmetic(
       return info.getFloat128Format();
     }
 
-    assert(false && "Unsupported float type semantics");
+    llvm_unreachable("Unsupported float type semantics");
   };
 
   const mlir::Type higherElementType = getHigherPrecisionFPType(elementType);