[spirv-reader][ir] Support OpNop

Handle the SPIR-V `OpNop` instruction.

Bug: 42250952
Change-Id: I8e807f2341f3dd879ab2ff6cca430992d3fcd192
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/220495
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: dan sinclair <dsinclair@chromium.org>

src/tint/lang/spirv/reader/parser/BUILD.bazel

diff --git a/src/tint/lang/spirv/reader/parser/BUILD.bazel b/src/tint/lang/spirv/reader/parser/BUILD.bazel
index 4d6b347..3442711 100644
--- a/src/tint/lang/spirv/reader/parser/BUILD.bazel
+++ b/src/tint/lang/spirv/reader/parser/BUILD.bazel
@@ -84,6 +84,7 @@
     "function_test.cc",
     "helper_test.h",
     "memory_test.cc",
+    "misc_test.cc",
     "struct_test.cc",
     "var_test.cc",
   ],

src/tint/lang/spirv/reader/parser/BUILD.cmake

diff --git a/src/tint/lang/spirv/reader/parser/BUILD.cmake b/src/tint/lang/spirv/reader/parser/BUILD.cmake
index 5c09a18..baf96ae 100644
--- a/src/tint/lang/spirv/reader/parser/BUILD.cmake
+++ b/src/tint/lang/spirv/reader/parser/BUILD.cmake
@@ -93,6 +93,7 @@
   lang/spirv/reader/parser/function_test.cc
   lang/spirv/reader/parser/helper_test.h
   lang/spirv/reader/parser/memory_test.cc
+  lang/spirv/reader/parser/misc_test.cc
   lang/spirv/reader/parser/struct_test.cc
   lang/spirv/reader/parser/var_test.cc
 )

src/tint/lang/spirv/reader/parser/BUILD.gn

diff --git a/src/tint/lang/spirv/reader/parser/BUILD.gn b/src/tint/lang/spirv/reader/parser/BUILD.gn
index 53d22ff..85af7ad 100644
--- a/src/tint/lang/spirv/reader/parser/BUILD.gn
+++ b/src/tint/lang/spirv/reader/parser/BUILD.gn
@@ -92,6 +92,7 @@
         "function_test.cc",
         "helper_test.h",
         "memory_test.cc",
+        "misc_test.cc",
         "struct_test.cc",
         "var_test.cc",
       ]

src/tint/lang/spirv/reader/parser/misc_test.cc

diff --git a/src/tint/lang/spirv/reader/parser/misc_test.cc b/src/tint/lang/spirv/reader/parser/misc_test.cc
new file mode 100644
index 0000000..7d55b5a
--- /dev/null
+++ b/src/tint/lang/spirv/reader/parser/misc_test.cc
@@ -0,0 +1,56 @@
+// Copyright 2024 The Dawn & Tint Authors
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this
+//    list of conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its
+//    contributors may be used to endorse or promote products derived from
+//    this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "src/tint/lang/spirv/reader/parser/helper_test.h"
+
+namespace tint::spirv::reader {
+namespace {
+
+TEST_F(SpirvParserTest, Misc_OpNop) {
+    EXPECT_IR(R"(
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint GLCompute %main "main"
+               OpExecutionMode %main LocalSize 1 1 1
+       %void = OpTypeVoid
+    %ep_type = OpTypeFunction %void
+       %main = OpFunction %void None %ep_type
+ %main_start = OpLabel
+               OpNop
+               OpReturn
+               OpFunctionEnd
+)",
+              R"(
+%main = @compute @workgroup_size(1u, 1u, 1u) func():void {
+  $B1: {
+    ret
+  }
+)");
+}
+
+}  // namespace
+}  // namespace tint::spirv::reader

src/tint/lang/spirv/reader/parser/parser.cc

diff --git a/src/tint/lang/spirv/reader/parser/parser.cc b/src/tint/lang/spirv/reader/parser/parser.cc
index b675cb1..7f5606b 100644
--- a/src/tint/lang/spirv/reader/parser/parser.cc
+++ b/src/tint/lang/spirv/reader/parser/parser.cc
@@ -502,6 +502,8 @@
         TINT_SCOPED_ASSIGNMENT(current_block_, dst);
         for (auto& inst : src) {
             switch (inst.opcode()) {
+                case spv::Op::OpNop:
+                    break;
                 case spv::Op::OpAccessChain:
                 case spv::Op::OpInBoundsAccessChain:
                     EmitAccess(inst);