[ir] Guard SPIR-V transforms in build files

We only need to build these transforms if we are building the SPIR-V
writer.

Bug: tint:1906
Change-Id: Ia54747b3c14c9bac0bbfe676880eb15781051c21
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/140892
Auto-Submit: James Price <jrprice@google.com>
Kokoro: James Price <jrprice@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: James Price <jrprice@google.com>
diff --git a/src/tint/BUILD.gn b/src/tint/BUILD.gn
index 8fcc1f8..739f5b3 100644
--- a/src/tint/BUILD.gn
+++ b/src/tint/BUILD.gn
@@ -525,14 +525,8 @@
       "ir/transform/block_decorated_structs.h",
       "ir/transform/demote_to_helper.cc",
       "ir/transform/demote_to_helper.h",
-      "ir/transform/merge_return.cc",
-      "ir/transform/merge_return.h",
       "ir/transform/shader_io.cc",
       "ir/transform/shader_io.h",
-      "ir/transform/shader_io_spirv.cc",
-      "ir/transform/shader_io_spirv.h",
-      "ir/transform/var_for_dynamic_index.cc",
-      "ir/transform/var_for_dynamic_index.h",
     ]
     deps = [
       ":libtint_builtins_src",
@@ -546,6 +540,12 @@
       sources += [
         "ir/transform/builtin_polyfill_spirv.cc",
         "ir/transform/builtin_polyfill_spirv.h",
+        "ir/transform/merge_return.cc",
+        "ir/transform/merge_return.h",
+        "ir/transform/shader_io_spirv.cc",
+        "ir/transform/shader_io_spirv.h",
+        "ir/transform/var_for_dynamic_index.cc",
+        "ir/transform/var_for_dynamic_index.h",
       ]
     }
   }
@@ -1894,10 +1894,7 @@
         "ir/transform/add_empty_entry_point_test.cc",
         "ir/transform/block_decorated_structs_test.cc",
         "ir/transform/demote_to_helper_test.cc",
-        "ir/transform/merge_return_test.cc",
-        "ir/transform/shader_io_test.cc",
         "ir/transform/test_helper.h",
-        "ir/transform/var_for_dynamic_index_test.cc",
       ]
 
       deps = [
@@ -1907,7 +1904,12 @@
       ]
 
       if (tint_build_spv_writer) {
-        sources += [ "ir/transform/builtin_polyfill_spirv_test.cc" ]
+        sources += [
+          "ir/transform/builtin_polyfill_spirv_test.cc",
+          "ir/transform/merge_return_test.cc",
+          "ir/transform/shader_io_spirv_test.cc",
+          "ir/transform/var_for_dynamic_index_test.cc",
+        ]
       }
     }
   }
diff --git a/src/tint/CMakeLists.txt b/src/tint/CMakeLists.txt
index 16f0b30..7ac4f43 100644
--- a/src/tint/CMakeLists.txt
+++ b/src/tint/CMakeLists.txt
@@ -679,6 +679,12 @@
     list(APPEND TINT_LIB_SRCS
       ir/transform/builtin_polyfill_spirv.cc
       ir/transform/builtin_polyfill_spirv.h
+      ir/transform/merge_return.cc
+      ir/transform/merge_return.h
+      ir/transform/shader_io_spirv.cc
+      ir/transform/shader_io_spirv.h
+      ir/transform/var_for_dynamic_index.cc
+      ir/transform/var_for_dynamic_index.h
       writer/spirv/ir/generator_impl_ir.cc
       writer/spirv/ir/generator_impl_ir.h
     )
@@ -848,16 +854,10 @@
     ir/transform/block_decorated_structs.h
     ir/transform/demote_to_helper.cc
     ir/transform/demote_to_helper.h
-    ir/transform/merge_return.cc
-    ir/transform/merge_return.h
     ir/transform/shader_io.cc
     ir/transform/shader_io.h
-    ir/transform/shader_io_spirv.cc
-    ir/transform/shader_io_spirv.h
     ir/transform/transform.cc
     ir/transform/transform.h
-    ir/transform/var_for_dynamic_index.cc
-    ir/transform/var_for_dynamic_index.h
   )
 endif()
 
@@ -1330,6 +1330,9 @@
     if(${TINT_BUILD_IR})
       list(APPEND TINT_TEST_SRCS
         ir/transform/builtin_polyfill_spirv_test.cc
+        ir/transform/merge_return_test.cc
+        ir/transform/shader_io_spirv_test.cc
+        ir/transform/var_for_dynamic_index_test.cc
         writer/spirv/ir/generator_impl_ir_access_test.cc
         writer/spirv/ir/generator_impl_ir_binary_test.cc
         writer/spirv/ir/generator_impl_ir_bitcast_test.cc
@@ -1621,9 +1624,6 @@
       ir/transform/add_empty_entry_point_test.cc
       ir/transform/block_decorated_structs_test.cc
       ir/transform/demote_to_helper_test.cc
-      ir/transform/merge_return_test.cc
-      ir/transform/shader_io_test.cc
-      ir/transform/var_for_dynamic_index_test.cc
       ir/unary_test.cc
       ir/user_call_test.cc
       ir/validate_test.cc
diff --git a/src/tint/ir/transform/shader_io_test.cc b/src/tint/ir/transform/shader_io_spirv_test.cc
similarity index 99%
rename from src/tint/ir/transform/shader_io_test.cc
rename to src/tint/ir/transform/shader_io_spirv_test.cc
index 7f18722..1717e5c 100644
--- a/src/tint/ir/transform/shader_io_test.cc
+++ b/src/tint/ir/transform/shader_io_spirv_test.cc
@@ -14,7 +14,6 @@
 
 #include <utility>
 
-#include "src/tint/ir/transform/shader_io.h"
 #include "src/tint/ir/transform/shader_io_spirv.h"
 #include "src/tint/ir/transform/test_helper.h"
 #include "src/tint/type/struct.h"