[Mlir-commits] [mlir] [mlir][SPIR-V] Deserialize Volatile function parameter decorations (PR #232195)

[Alexander Shaposhnikov]

https://github.com/alexander-shaposhnikov created https://github.com/llvm/llvm-project/pull/232195

The serializer already supports Volatile function parameter decorations, but the deserializer rejects them. Accept Volatile using the existing spirv.decoration argument attribute, allowing these parameters to survive binary round trips.

>From 880cbd2119f122848154dcaafdf2cd88a668d072 Mon Sep 17 00:00:00 2001
From: Alexander Shaposhnikov <alexander.v.shaposhnikov at gmail.com>
Date: Wed, 14 Oct 2026 23:22:26 -0700
Subject: [PATCH] [mlir][SPIR-V] Deserialize Volatile function parameter
 decorations

The serializer already supports Volatile function parameter decorations,
but the deserializer rejects them. Accept Volatile using the existing
spirv.decoration argument attribute, allowing these parameters to survive
binary round trips.

Add round-trip tests for function definitions and imported declarations,
including Volatile combined with Alignment and FuncParamAttr decorations.
Extend the deserialization tests to check that unsupported decorations are
still rejected when present alongside Volatile.
---
 .../SPIRV/Deserialization/Deserializer.cpp    | 21 +++++++------
 .../SPIRV/function-parameter-attributes.mlir  | 30 +++++++++++++++++++
 .../Dialect/SPIRV/DeserializationTest.cpp     | 12 ++++----
 3 files changed, 48 insertions(+), 15 deletions(-)

diff --git a/mlir/lib/Target/SPIRV/Deserialization/Deserializer.cpp b/mlir/lib/Target/SPIRV/Deserialization/Deserializer.cpp
index 1cdc5686adfeb2..02c76515a5fed8 100644
--- a/mlir/lib/Target/SPIRV/Deserialization/Deserializer.cpp
+++ b/mlir/lib/Target/SPIRV/Deserialization/Deserializer.cpp
@@ -547,21 +547,24 @@ LogicalResult spirv::Deserializer::setFunctionArgAttrs(
     if (handled)
       continue;
 
-    if (decAttr.getName() == getSymbolDecoration(stringifyDecoration(
-                                 spirv::Decoration::RelaxedPrecision))) {
-      // TODO: Current implementation supports only one decoration per function
-      // parameter so RelaxedPrecision cannot be applied at the same time as,
-      // for example, Aliased/Restrict/etc. This should be relaxed to allow any
-      // combination of decoration allowed by the spec to be supported.
+    for (auto decoration :
+         {spirv::Decoration::RelaxedPrecision, spirv::Decoration::Volatile}) {
+      if (decAttr.getName() !=
+          getSymbolDecoration(stringifyDecoration(decoration)))
+        continue;
+
+      // TODO: Support multiple decorations per function parameter.
       if (foundDecorationAttr)
         return emitError(unknownLoc, "already found a decoration for function "
                                      "argument with result <id> ")
                << argID;
 
-      foundDecorationAttr = spirv::DecorationAttr::get(
-          context, spirv::Decoration::RelaxedPrecision);
-      continue;
+      foundDecorationAttr = spirv::DecorationAttr::get(context, decoration);
+      handled = true;
+      break;
     }
+    if (handled)
+      continue;
 
     return emitError(unknownLoc, "unhandled decoration '")
            << decAttr.getName().getValue()
diff --git a/mlir/test/Target/SPIRV/function-parameter-attributes.mlir b/mlir/test/Target/SPIRV/function-parameter-attributes.mlir
index 3559aef561601b..31b89fd29aed3f 100644
--- a/mlir/test/Target/SPIRV/function-parameter-attributes.mlir
+++ b/mlir/test/Target/SPIRV/function-parameter-attributes.mlir
@@ -103,3 +103,33 @@ spirv.module Physical64 OpenCL requires #spirv.vce<v1.0, [Addresses, Kernel, Lin
     linkage_attributes = #spirv.linkage_attributes<linkage_name = "external", linkage_type = <Import>>
   }
 }
+
+// -----
+
+// `volatile` pointer parameters are decorated with Volatile; it may be combined
+// with Alignment and FuncParamAttr decorations.
+spirv.module Physical64 OpenCL requires #spirv.vce<v1.0, [Addresses, Kernel, Linkage], []> {
+  // CHECK-LABEL: spirv.func @volatile(
+  // CHECK-SAME: !spirv.ptr<i32, CrossWorkgroup> {spirv.decoration = #spirv.decoration<Volatile>}
+  // CHECK-SAME: !spirv.ptr<i32, CrossWorkgroup> {spirv.alignment = 4 : i32, spirv.decoration = #spirv.decoration<Volatile>, spirv.func_param_attr = [#spirv.function_parameter_attribute<NoCapture>]}
+  spirv.func @volatile(
+      %a: !spirv.ptr<i32, CrossWorkgroup> {spirv.decoration = #spirv.decoration<Volatile>},
+      %b: !spirv.ptr<i32, CrossWorkgroup> {
+        spirv.alignment = 4 : i32,
+        spirv.decoration = #spirv.decoration<Volatile>,
+        spirv.func_param_attr = [#spirv.function_parameter_attribute<NoCapture>]}
+  ) "None" {
+    spirv.Return
+  }
+
+}
+
+// -----
+
+spirv.module Physical64 OpenCL requires #spirv.vce<v1.0, [Addresses, Kernel, Linkage], []> {
+  // CHECK-LABEL: spirv.func @volatile_declaration(
+  // CHECK-SAME: !spirv.ptr<i32, CrossWorkgroup> {spirv.decoration = #spirv.decoration<Volatile>}
+  spirv.func @volatile_declaration(%arg: !spirv.ptr<i32, CrossWorkgroup> {spirv.decoration = #spirv.decoration<Volatile>}) "None" attributes {
+    linkage_attributes = #spirv.linkage_attributes<linkage_name = "volatile_declaration", linkage_type = <Import>>
+  }
+}
diff --git a/mlir/unittests/Dialect/SPIRV/DeserializationTest.cpp b/mlir/unittests/Dialect/SPIRV/DeserializationTest.cpp
index db19eb9e222c1b..3bb757ae93e651 100644
--- a/mlir/unittests/Dialect/SPIRV/DeserializationTest.cpp
+++ b/mlir/unittests/Dialect/SPIRV/DeserializationTest.cpp
@@ -298,12 +298,12 @@ TEST_P(UnsupportedParameterDecorationTest, RejectWithSupportedDecoration) {
                    "result <id> 1");
 }
 
-INSTANTIATE_TEST_SUITE_P(
-    SPIRV, UnsupportedParameterDecorationTest,
-    ::testing::Values(spirv::Decoration::Alignment,
-                      spirv::Decoration::FuncParamAttr,
-                      spirv::Decoration::Restrict,
-                      spirv::Decoration::RelaxedPrecision));
+INSTANTIATE_TEST_SUITE_P(SPIRV, UnsupportedParameterDecorationTest,
+                         ::testing::Values(spirv::Decoration::Alignment,
+                                           spirv::Decoration::FuncParamAttr,
+                                           spirv::Decoration::Restrict,
+                                           spirv::Decoration::RelaxedPrecision,
+                                           spirv::Decoration::Volatile));
 
 TEST_F(DeserializationTest, AlignmentMissingOperand) {
   addHeader();