spirv-reader: switch to HLSL-style pipeline IO

- When storing to sample_mask output, write to the 0th element
- Only make a return struct if it has members
- Adjust type signedness coercion when loading special builtins.
- Adapt tests

- Update expectations for end-to-end tests

- Handle sample_mask with stride
  Input variables normally don't have layout. But they can have it
  up through SPIR-V 1.4.
  Handle this case in the SPIR-V reader, by seeing through the
  intermediate alias type created for the strided array type.

Bug: tint:508
Change-Id: I0f19dc1305d3f250dbbc0698a602288c34245274
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/54743
Auto-Submit: David Neto <dneto@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: James Price <jrprice@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>

test/ptr_ref/load/param/ptr.spvasm.expected.hlsl

@@ -3,11 +3,16 @@ int func(int value, inout int pointer) {
   return (value + x_9);
 }
 
-[numthreads(1, 1, 1)]
-void main() {
+void main_1() {
   int i = 0;
   i = 123;
   const int x_19 = i;
   const int x_18 = func(x_19, i);
   return;
 }
+
+[numthreads(1, 1, 1)]
+void main() {
+  main_1();
+  return;
+}

test/ptr_ref/load/param/ptr.spvasm.expected.msl

@@ -6,7 +6,7 @@ int func(int value, thread int* const pointer) {
   return (value + x_9);
 }
 
-kernel void tint_symbol() {
+void main_1() {
   int i = 0;
   i = 123;
   int const x_19 = i;
@@ -14,3 +14,8 @@ kernel void tint_symbol() {
   return;
 }
 
+kernel void tint_symbol() {
+  main_1();
+  return;
+}
+

test/ptr_ref/load/param/ptr.spvasm.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 22
+; Bound: 25
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -10,8 +10,9 @@
                OpName %func "func"
                OpName %value "value"
                OpName %pointer "pointer"
-               OpName %main "main"
+               OpName %main_1 "main_1"
                OpName %i "i"
+               OpName %main "main"
         %int = OpTypeInt 32 1
 %_ptr_Function_int = OpTypePointer Function %int
           %1 = OpTypeFunction %int %int %_ptr_Function_int
@@ -28,7 +29,7 @@
          %10 = OpIAdd %int %value %9
                OpReturnValue %10
                OpFunctionEnd
-       %main = OpFunction %void None %11
+     %main_1 = OpFunction %void None %11
          %14 = OpLabel
           %i = OpVariable %_ptr_Function_int Function %17
                OpStore %i %int_0
@@ -37,3 +38,8 @@
          %20 = OpFunctionCall %int %func %19 %i
                OpReturn
                OpFunctionEnd
+       %main = OpFunction %void None %11
+         %23 = OpLabel
+         %24 = OpFunctionCall %void %main_1
+               OpReturn
+               OpFunctionEnd

test/ptr_ref/load/param/ptr.spvasm.expected.wgsl

@@ -3,11 +3,15 @@ fn func(value : i32, pointer : ptr<function, i32>) -> i32 {
   return (value + x_9);
 }
 
-[[stage(compute)]]
-fn main() {
+fn main_1() {
   var i : i32 = 0;
   i = 123;
   let x_19 : i32 = i;
   let x_18 : i32 = func(x_19, &(i));
   return;
 }
+
+[[stage(compute)]]
+fn main() {
+  main_1();
+}