spirv-val: Fix crash with bad OpUntypedArrayLengthKHR (#6493)

working on the internal extension (and being new to Untyped Pointers
still) I accidentally set the `OpUntypedArrayLengthKHR` Pointer ID to be
`OpTypeUntypedPointerKHR` and it just crashed in `spirv-val`... so now
it doesn't crash and provides hopefully a likely good answer for the
next person like me

... the issue is `pointer` and `type` are really easy to mix up...
`OpTypeUntyped` will always be my favorite thing to explain to those new
to SPIR-V 😄

Author: spencer-lunarg

source/val/validate_memory.cpp

@@ -2140,9 +2140,10 @@ spv_result_t ValidateArrayLength(ValidationState_t& state,
   auto pointer_ty_id = state.GetOperandTypeId(inst, (untyped ? 3 : 2));
   auto pointer_ty = state.FindDef(pointer_ty_id);
   if (untyped) {
-    if (pointer_ty->opcode() != spv::Op::OpTypeUntypedPointerKHR) {
+    if (!pointer_ty ||
+        pointer_ty->opcode() != spv::Op::OpTypeUntypedPointerKHR) {
       return state.diag(SPV_ERROR_INVALID_ID, inst)
-             << "Pointer must be an untyped pointer";
+             << "Pointer must be an untyped pointer object";
     }
   } else if (pointer_ty->opcode() != spv::Op::OpTypePointer) {
     return state.diag(SPV_ERROR_INVALID_ID, inst)

test/val/val_memory_test.cpp

@@ -8010,7 +8010,46 @@ OpFunctionEnd
   CompileSuccessfully(spirv, SPV_ENV_UNIVERSAL_1_3);
   EXPECT_EQ(SPV_ERROR_INVALID_ID, ValidateInstructions(SPV_ENV_UNIVERSAL_1_3));
   EXPECT_THAT(getDiagnosticString(),
-              HasSubstr("Pointer must be an untyped pointer"));
+              HasSubstr("Pointer must be an untyped pointer object"));
+}
+
+TEST_F(ValidateMemory, UntypedArrayLengthBadPointer2) {
+  const std::string spirv = R"(
+               OpCapability Shader
+               OpCapability UntypedPointersKHR
+               OpCapability Int64
+               OpExtension "SPV_KHR_untyped_pointers"
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint GLCompute %main "main" %b
+               OpExecutionMode %main LocalSize 1 1 1
+               OpDecorate %_runtimearr_float ArrayStride 4
+               OpDecorate %B Block
+               OpMemberDecorate %B 0 NonWritable
+               OpMemberDecorate %B 0 Offset 0
+               OpDecorate %b NonWritable
+               OpDecorate %b Binding 0
+               OpDecorate %b DescriptorSet 0
+       %void = OpTypeVoid
+          %4 = OpTypeFunction %void
+      %float = OpTypeFloat 32
+%_runtimearr_float = OpTypeRuntimeArray %float
+          %B = OpTypeStruct %_runtimearr_float
+        %ptr = OpTypeUntypedPointerKHR StorageBuffer
+          %b = OpUntypedVariableKHR %ptr StorageBuffer %B
+      %ulong = OpTypeInt 64 0
+       %long = OpTypeInt 64 1
+       %main = OpFunction %void None %4
+          %6 = OpLabel
+         %13 = OpUntypedArrayLengthKHR %ulong %b %ptr 0
+         %15 = OpBitcast %long %13
+               OpReturn
+               OpFunctionEnd
+)";
+
+  CompileSuccessfully(spirv, SPV_ENV_UNIVERSAL_1_3);
+  EXPECT_EQ(SPV_ERROR_INVALID_ID, ValidateInstructions(SPV_ENV_UNIVERSAL_1_3));
+  EXPECT_THAT(getDiagnosticString(),
+              HasSubstr("Pointer must be an untyped pointer object"));
 }
 
 TEST_F(ValidateMemory, UntypedArrayLengtBadStruct) {