[Mlir-commits] [mlir] [mlir][spirv] Print and parse discardable attributes on spec constants (PR #227669)

[Samarth Narang]

https://github.com/snarang181 created https://github.com/llvm/llvm-project/pull/227669

The custom assembly formats of spirv.SpecConstant, spirv.SpecConstantComposite and spirv.EXT.SpecConstantCompositeReplicate never printed or parsed the discardable attribute dictionary, so any such attribute survived the generic form and bytecode but was silently dropped by a textual round trip. 

Fixes #225260

>From 3ae79d870bc7259232211fc67875a2cc085333c1 Mon Sep 17 00:00:00 2001
From: Samarth Narang <sn2910 at nyu.edu>
Date: Thu, 24 Sep 2026 12:14:48 +0000
Subject: [PATCH] [mlir][spirv] Print and parse discardable attributes on spec
 constants

The custom assembly formats of spirv.SpecConstant,
spirv.SpecConstantComposite and spirv.EXT.SpecConstantCompositeReplicate
never printed or parsed the discardable attribute dictionary, so any such
attribute survived the generic form and bytecode but was silently dropped by
a textual round trip. Print the dictionary after the existing syntax and
parse it back. spirv.SpecConstant keeps printing spec_id with its dedicated
syntax and elides it from the dictionary.

Fixes #225260
---
 mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp        | 13 ++++++++++---
 mlir/test/Dialect/SPIRV/IR/structure-ops.mlir | 14 ++++++++++++++
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp b/mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp
index 37ae6a942e491..f967ca61f3349 100644
--- a/mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp
+++ b/mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp
@@ -1902,7 +1902,7 @@ ParseResult spirv::SpecConstantOp::parse(OpAsmParser &parser,
       parser.parseAttribute(valueAttr, defaultValueAttrName, result.attributes))
     return failure();
 
-  return success();
+  return parser.parseOptionalAttrDict(result.attributes);
 }
 
 void spirv::SpecConstantOp::print(OpAsmPrinter &printer) {
@@ -1914,6 +1914,9 @@ void spirv::SpecConstantOp::print(OpAsmPrinter &printer) {
           (*this)->getDiscardableAttrOfType<IntegerAttr>(kSpecIdAttrName))
     printer << ' ' << kSpecIdAttrName << '(' << specID.getInt() << ')';
   printer << " = " << getDefaultValue();
+  printer.printOptionalAttrDict(
+      (*this)->getDiscardableAttrDictionary().getValue(),
+      /*elidedAttrs=*/{kSpecIdAttrName});
 }
 
 LogicalResult spirv::SpecConstantOp::verify() {
@@ -2009,7 +2012,7 @@ ParseResult spirv::SpecConstantCompositeOp::parse(OpAsmParser &parser,
       spirv::SpecConstantCompositeOp::getTypeAttrName(result.name);
   result.addAttribute(typeAttrName, TypeAttr::get(type));
 
-  return success();
+  return parser.parseOptionalAttrDict(result.attributes);
 }
 
 void spirv::SpecConstantCompositeOp::print(OpAsmPrinter &printer) {
@@ -2019,6 +2022,8 @@ void spirv::SpecConstantCompositeOp::print(OpAsmPrinter &printer) {
   printer.printSymbolName(getSymName());
   printer << " (" << llvm::interleaved(this->getConstituents().getValue())
           << ") : " << getType();
+  printer.printOptionalAttrDict(
+      (*this)->getDiscardableAttrDictionary().getValue());
 }
 
 LogicalResult spirv::SpecConstantCompositeOp::verify() {
@@ -2098,7 +2103,7 @@ spirv::EXTSpecConstantCompositeReplicateOp::parse(OpAsmParser &parser,
       spirv::EXTSpecConstantCompositeReplicateOp::getTypeAttrName(result.name);
   result.addAttribute(typeAttrName, TypeAttr::get(type));
 
-  return success();
+  return parser.parseOptionalAttrDict(result.attributes);
 }
 
 void spirv::EXTSpecConstantCompositeReplicateOp::print(OpAsmPrinter &printer) {
@@ -2107,6 +2112,8 @@ void spirv::EXTSpecConstantCompositeReplicateOp::print(OpAsmPrinter &printer) {
     printer << visibility.getValue() << ' ';
   printer.printSymbolName(getSymName());
   printer << " (" << this->getConstituent() << ") : " << getType();
+  printer.printOptionalAttrDict(
+      (*this)->getDiscardableAttrDictionary().getValue());
 }
 
 LogicalResult spirv::EXTSpecConstantCompositeReplicateOp::verify() {
diff --git a/mlir/test/Dialect/SPIRV/IR/structure-ops.mlir b/mlir/test/Dialect/SPIRV/IR/structure-ops.mlir
index 4acaa417501ac..799bc9e0c82d2 100644
--- a/mlir/test/Dialect/SPIRV/IR/structure-ops.mlir
+++ b/mlir/test/Dialect/SPIRV/IR/structure-ops.mlir
@@ -1372,3 +1372,17 @@ spirv.module Logical GLSL450 {
     spirv.Return
   }
 }
+
+// -----
+
+// Discardable attributes round-trip through the custom syntax.
+spirv.module Logical GLSL450 {
+  // CHECK: spirv.SpecConstant @sc_attrs spec_id(5) = 1 : i32 {test.marker = "keep"}
+  spirv.SpecConstant @sc_attrs spec_id(5) = 1 : i32 {test.marker = "keep"}
+  // CHECK: spirv.SpecConstant @sc = 1 : i32
+  spirv.SpecConstant @sc = 1 : i32
+  // CHECK: spirv.SpecConstantComposite @scc_attrs (@sc, @sc) : vector<2xi32> {test.marker = "keep"}
+  spirv.SpecConstantComposite @scc_attrs (@sc, @sc) : vector<2xi32> {test.marker = "keep"}
+  // CHECK: spirv.EXT.SpecConstantCompositeReplicate @sccr_attrs (@sc) : vector<2xi32> {test.marker = "keep"}
+  spirv.EXT.SpecConstantCompositeReplicate @sccr_attrs (@sc) : vector<2xi32> {test.marker = "keep"}
+}