1 files changed, 12 insertions, 5 deletions
diff --git a/mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp b/mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp
index fe50865..0c8114d 100644
--- a/mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp
+++ b/mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp
@@ -1276,12 +1276,19 @@ LogicalResult spirv::GlobalVariableOp::verify() {
     Operation *initOp = SymbolTable::lookupNearestSymbolFrom(
         (*this)->getParentOp(), init.getAttr());
     // TODO: Currently only variable initialization with specialization
-    // constants and other variables is supported. They could be normal
-    // constants in the module scope as well.
-    if (!initOp || !isa<spirv::GlobalVariableOp, spirv::SpecConstantOp,
-                        spirv::SpecConstantCompositeOp>(initOp)) {
+    // constants is supported. There could be normal constants in the module
+    // scope as well.
+    //
+    // In the current setup we also cannot initialize one global variable with
+    // another. The problem is that if we try to initialize pointer of type X
+    // with another pointer type, the validator fails because it expects the
+    // variable to be initialized to be type X, not pointer to X. Now
+    // `spirv.GlobalVariable` only allows pointer type, so in the current design
+    // we cannot initialize one `spirv.GlobalVariable` with another.
+    if (!initOp ||
+        !isa<spirv::SpecConstantOp, spirv::SpecConstantCompositeOp>(initOp)) {
       return emitOpError("initializer must be result of a "
-                         "spirv.SpecConstant or spirv.GlobalVariable or "
+                         "spirv.SpecConstant or "
                          "spirv.SpecConstantCompositeOp op");
     }
   }