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/global/i32.spvasm.expected.hlsl

@@ -1,8 +1,13 @@
 static int I = 0;
 
-[numthreads(1, 1, 1)]
-void main() {
+void main_1() {
   const int x_9 = I;
   const int x_11 = (x_9 + 1);
   return;
 }
+
+[numthreads(1, 1, 1)]
+void main() {
+  main_1();
+  return;
+}

test/ptr_ref/load/global/i32.spvasm.expected.msl

@@ -1,10 +1,15 @@
 #include <metal_stdlib>
 
 using namespace metal;
-kernel void tint_symbol() {
-  thread int tint_symbol_1 = 0;
-  int const x_9 = tint_symbol_1;
+void main_1(thread int* const tint_symbol_1) {
+  int const x_9 = *(tint_symbol_1);
   int const x_11 = (x_9 + 1);
   return;
 }
 
+kernel void tint_symbol() {
+  thread int tint_symbol_2 = 0;
+  main_1(&(tint_symbol_2));
+  return;
+}
+

test/ptr_ref/load/global/i32.spvasm.expected.spvasm

@@ -1,13 +1,14 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 12
+; Bound: 15
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
                OpName %I "I"
+               OpName %main_1 "main_1"
                OpName %main "main"
         %int = OpTypeInt 32 1
       %int_0 = OpConstant %int 0
@@ -16,9 +17,14 @@
        %void = OpTypeVoid
           %5 = OpTypeFunction %void
       %int_1 = OpConstant %int 1
-       %main = OpFunction %void None %5
+     %main_1 = OpFunction %void None %5
           %8 = OpLabel
           %9 = OpLoad %int %I
          %11 = OpIAdd %int %9 %int_1
                OpReturn
                OpFunctionEnd
+       %main = OpFunction %void None %5
+         %13 = OpLabel
+         %14 = OpFunctionCall %void %main_1
+               OpReturn
+               OpFunctionEnd

test/ptr_ref/load/global/i32.spvasm.expected.wgsl

@@ -1,8 +1,12 @@
 var<private> I : i32 = 0;
 
-[[stage(compute)]]
-fn main() {
+fn main_1() {
   let x_9 : i32 = I;
   let x_11 : i32 = (x_9 + 1);
   return;
 }
+
+[[stage(compute)]]
+fn main() {
+  main_1();
+}

test/ptr_ref/load/global/struct_field.spvasm.expected.hlsl

@@ -4,10 +4,15 @@ struct S {
 
 static S V;
 
-[numthreads(1, 1, 1)]
-void main() {
+void main_1() {
   int i = 0;
   const int x_15 = V.i;
   i = x_15;
   return;
 }
+
+[numthreads(1, 1, 1)]
+void main() {
+  main_1();
+  return;
+}

test/ptr_ref/load/global/struct_field.spvasm.expected.msl

@@ -5,11 +5,16 @@ struct S {
   int i;
 };
 
-kernel void tint_symbol() {
-  thread S tint_symbol_1 = {};
+void main_1(thread S* const tint_symbol_1) {
   int i = 0;
-  int const x_15 = tint_symbol_1.i;
+  int const x_15 = (*(tint_symbol_1)).i;
   i = x_15;
   return;
 }
 
+kernel void tint_symbol() {
+  thread S tint_symbol_2 = {};
+  main_1(&(tint_symbol_2));
+  return;
+}
+

test/ptr_ref/load/global/struct_field.spvasm.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 18
+; Bound: 21
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -10,8 +10,9 @@
                OpName %S "S"
                OpMemberName %S 0 "i"
                OpName %V "V"
-               OpName %main "main"
+               OpName %main_1 "main_1"
                OpName %i "i"
+               OpName %main "main"
                OpMemberDecorate %S 0 Offset 0
         %int = OpTypeInt 32 1
           %S = OpTypeStruct %int
@@ -25,7 +26,7 @@
        %uint = OpTypeInt 32 0
      %uint_0 = OpConstant %uint 0
 %_ptr_Private_int = OpTypePointer Private %int
-       %main = OpFunction %void None %6
+     %main_1 = OpFunction %void None %6
           %9 = OpLabel
           %i = OpVariable %_ptr_Function_int Function %12
          %16 = OpAccessChain %_ptr_Private_int %V %uint_0
@@ -33,3 +34,8 @@
                OpStore %i %17
                OpReturn
                OpFunctionEnd
+       %main = OpFunction %void None %6
+         %19 = OpLabel
+         %20 = OpFunctionCall %void %main_1
+               OpReturn
+               OpFunctionEnd

test/ptr_ref/load/global/struct_field.spvasm.expected.wgsl

@@ -4,10 +4,14 @@ struct S {
 
 var<private> V : S;
 
-[[stage(compute)]]
-fn main() {
+fn main_1() {
   var i : i32;
   let x_15 : i32 = V.i;
   i = x_15;
   return;
 }
+
+[[stage(compute)]]
+fn main() {
+  main_1();
+}