[mlir][spirv] Enable validation of global vars tests (llvm#164974)

Currently the target test will fail with:

```
error: line 12: Initializer type must match the data type
  %var2 = OpVariable %_ptr_Uniform_float Uniform %var1
```

When passed:

```mlir
spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader], []> {
  spirv.GlobalVariable @var1 : !spirv.ptr<f32, Uniform>
  spirv.GlobalVariable @var2 initializer(@var1) bind(1, 0) : !spirv.ptr<f32, Uniform>
}
```

The problem is that we try to initialize `f32` pointer with `f32`
pointer, but the validator fails because it expects `var1` to be `f32`,
not a pointer to `f32`. `spirv.GlobalVariable` only allows pointer type,
so in the current design we cannot initialize one `spirv.GlobalVariable`
with another.

So, for now we disallow initialization of one global variable with
another. In the future we may want to re-work global variables if we
want to support that.

Author: IgWod-IMG

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");
     }
   }

mlir/test/Dialect/SPIRV/IR/structure-ops.mlir

@@ -501,7 +501,7 @@ spirv.module Logical GLSL450 {
 // -----
 
 spirv.module Logical GLSL450 {
-  // expected-error @+1 {{op initializer must be result of a spirv.SpecConstant or spirv.GlobalVariable or spirv.SpecConstantCompositeOp op}}
+  // expected-error @+1 {{op initializer must be result of a spirv.SpecConstant or spirv.SpecConstantCompositeOp op}}
   spirv.GlobalVariable @var0 initializer(@var1) : !spirv.ptr<f32, Private>
 }
 

mlir/test/Target/SPIRV/global-variable.mlir

@@ -1,11 +1,16 @@
 // RUN: mlir-translate -no-implicit-module -test-spirv-roundtrip -split-input-file %s | FileCheck %s
 
+// RUN: %if spirv-tools %{ rm -rf %t %}
+// RUN: %if spirv-tools %{ mkdir %t %}
+// RUN: %if spirv-tools %{ mlir-translate --no-implicit-module --serialize-spirv --split-input-file --spirv-save-validation-files-with-prefix=%t/module %s %}
+// RUN: %if spirv-tools %{ spirv-val %t %}
+
 // CHECK:      spirv.GlobalVariable @var0 bind(1, 0) : !spirv.ptr<f32, Input>
 // CHECK-NEXT: spirv.GlobalVariable @var1 bind(0, 1) : !spirv.ptr<f32, Output>
 // CHECK-NEXT: spirv.GlobalVariable @var2 built_in("GlobalInvocationId") : !spirv.ptr<vector<3xi32>, Input>
 // CHECK-NEXT: spirv.GlobalVariable @var3 built_in("GlobalInvocationId") : !spirv.ptr<vector<3xi32>, Input>
 
-spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader], []> {
+spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader, Linkage], []> {
   spirv.GlobalVariable @var0 bind(1, 0) : !spirv.ptr<f32, Input>
   spirv.GlobalVariable @var1 bind(0, 1) : !spirv.ptr<f32, Output>
   spirv.GlobalVariable @var2 {built_in = "GlobalInvocationId"} : !spirv.ptr<vector<3xi32>, Input>
@@ -14,16 +19,7 @@ spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader], []> {
 
 // -----
 
-spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader], []> {
-  // CHECK:         spirv.GlobalVariable @var1 : !spirv.ptr<f32, Input>
-  // CHECK-NEXT:    spirv.GlobalVariable @var2 initializer(@var1) bind(1, 0) : !spirv.ptr<f32, Input>
-  spirv.GlobalVariable @var1 : !spirv.ptr<f32, Input>
-  spirv.GlobalVariable @var2 initializer(@var1) bind(1, 0) : !spirv.ptr<f32, Input>
-}
-
-// -----
-
-spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader], []> {
+spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader, Linkage, Int8], []> {
   // CHECK:         spirv.SpecConstant @sc = 1 : i8
   // CHECK-NEXT:    spirv.GlobalVariable @var initializer(@sc) : !spirv.ptr<i8, Uniform>
   spirv.SpecConstant @sc = 1 : i8
@@ -33,7 +29,7 @@ spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader], []> {
 
 // -----
 
-spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader], []> {
+spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader, Linkage, Int8], []> {
   // CHECK:         spirv.SpecConstantComposite @scc (@sc0, @sc1, @sc2) : !spirv.array<3 x i8>
   // CHECK-NEXT:    spirv.GlobalVariable @var initializer(@scc) : !spirv.ptr<!spirv.array<3 x i8>, Uniform>
   spirv.SpecConstant @sc0 = 1 : i8
@@ -47,7 +43,7 @@ spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader], []> {
 
 // -----
 
-spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader], []> {
+spirv.module Logical GLSL450 requires #spirv.vce<v1.0, [Shader, Linkage], []> {
   spirv.GlobalVariable @globalInvocationID built_in("GlobalInvocationId") : !spirv.ptr<vector<3xi32>, Input>
   spirv.func @foo() "None" {
     // CHECK: %[[ADDR:.*]] = spirv.mlir.addressof @globalInvocationID : !spirv.ptr<vector<3xi32>, Input>