transform/shader_io: Generate a wrapper function

This is a major reworking of this transform. The old transform code
was getting unwieldy, with part of the complication coming from the
handling of multiple return statements. By generating a wrapper
function instead, we can avoid a lot of this complexity.

The original entry point function is stripped of all shader IO
attributes (as well as `stage` and `workgroup_size`), but the body is
left unmodified. A new entry point wrapper function is introduced
which calls the original function, packing/unpacking the shader inputs
as necessary, and propagates the result to the corresponding shader
outputs.

The new code has been refactored to use a state object with the
different parts of the transform split into separate functions, which
makes it much more manageable.

Fixed: tint:1076
Bug: tint:920
Change-Id: I3490a0ea7a3509a4e198ce730e476516649d8d96
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/60521
Auto-Submit: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: James Price <jrprice@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>

test/var/initialization/workgroup/array.wgsl.expected.hlsl

@@ -4,9 +4,7 @@ struct tint_symbol_1 {
   uint local_invocation_index : SV_GroupIndex;
 };
 
-[numthreads(1, 1, 1)]
-void main(tint_symbol_1 tint_symbol) {
-  const uint local_invocation_index = tint_symbol.local_invocation_index;
+void main_inner(uint local_invocation_index) {
   {
     for(uint idx = local_invocation_index; (idx < 3u); idx = (idx + 1u)) {
       const uint i = idx;
@@ -15,5 +13,10 @@ void main(tint_symbol_1 tint_symbol) {
   }
   GroupMemoryBarrierWithGroupSync();
   v;
+}
+
+[numthreads(1, 1, 1)]
+void main(tint_symbol_1 tint_symbol) {
+  main_inner(tint_symbol.local_invocation_index);
   return;
 }

test/var/initialization/workgroup/array.wgsl.expected.msl

@@ -5,14 +5,18 @@ struct tint_array_wrapper {
   int arr[3];
 };
 
-kernel void tint_symbol(uint local_invocation_index [[thread_index_in_threadgroup]]) {
-  threadgroup tint_array_wrapper tint_symbol_2;
+void tint_symbol_inner(uint local_invocation_index, threadgroup tint_array_wrapper* const tint_symbol_1) {
   for(uint idx = local_invocation_index; (idx < 3u); idx = (idx + 1u)) {
     uint const i = idx;
-    tint_symbol_2.arr[i] = int();
+    (*(tint_symbol_1)).arr[i] = int();
   }
   threadgroup_barrier(mem_flags::mem_threadgroup);
-  (void) tint_symbol_2;
+  (void) *(tint_symbol_1);
+}
+
+kernel void tint_symbol(uint local_invocation_index [[thread_index_in_threadgroup]]) {
+  threadgroup tint_array_wrapper tint_symbol_2;
+  tint_symbol_inner(local_invocation_index, &(tint_symbol_2));
   return;
 }
 

test/var/initialization/workgroup/matrix.wgsl.expected.hlsl

@@ -4,13 +4,16 @@ struct tint_symbol_1 {
   uint local_invocation_index : SV_GroupIndex;
 };
 
-[numthreads(1, 1, 1)]
-void main(tint_symbol_1 tint_symbol) {
-  const uint local_invocation_index = tint_symbol.local_invocation_index;
+void main_inner(uint local_invocation_index) {
   {
     v = float2x3(0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f);
   }
   GroupMemoryBarrierWithGroupSync();
   v;
+}
+
+[numthreads(1, 1, 1)]
+void main(tint_symbol_1 tint_symbol) {
+  main_inner(tint_symbol.local_invocation_index);
   return;
 }

test/var/initialization/workgroup/scalar.wgsl.expected.hlsl

@@ -4,13 +4,16 @@ struct tint_symbol_1 {
   uint local_invocation_index : SV_GroupIndex;
 };
 
-[numthreads(1, 1, 1)]
-void main(tint_symbol_1 tint_symbol) {
-  const uint local_invocation_index = tint_symbol.local_invocation_index;
+void main_inner(uint local_invocation_index) {
   {
     v = 0;
   }
   GroupMemoryBarrierWithGroupSync();
   v;
+}
+
+[numthreads(1, 1, 1)]
+void main(tint_symbol_1 tint_symbol) {
+  main_inner(tint_symbol.local_invocation_index);
   return;
 }

test/var/initialization/workgroup/scalar.wgsl.expected.msl

@@ -1,13 +1,17 @@
 #include <metal_stdlib>
 
 using namespace metal;
-kernel void tint_symbol(uint local_invocation_index [[thread_index_in_threadgroup]]) {
-  threadgroup int tint_symbol_2;
+void tint_symbol_inner(uint local_invocation_index, threadgroup int* const tint_symbol_1) {
   {
-    tint_symbol_2 = int();
+    *(tint_symbol_1) = int();
   }
   threadgroup_barrier(mem_flags::mem_threadgroup);
-  (void) tint_symbol_2;
+  (void) *(tint_symbol_1);
+}
+
+kernel void tint_symbol(uint local_invocation_index [[thread_index_in_threadgroup]]) {
+  threadgroup int tint_symbol_2;
+  tint_symbol_inner(local_invocation_index, &(tint_symbol_2));
   return;
 }
 

test/var/initialization/workgroup/struct.wgsl.expected.hlsl

@@ -9,14 +9,17 @@ struct tint_symbol_1 {
   uint local_invocation_index : SV_GroupIndex;
 };
 
-[numthreads(1, 1, 1)]
-void main(tint_symbol_1 tint_symbol) {
-  const uint local_invocation_index = tint_symbol.local_invocation_index;
+void main_inner(uint local_invocation_index) {
   {
     const S tint_symbol_2 = (S)0;
     v = tint_symbol_2;
   }
   GroupMemoryBarrierWithGroupSync();
   v;
+}
+
+[numthreads(1, 1, 1)]
+void main(tint_symbol_1 tint_symbol) {
+  main_inner(tint_symbol.local_invocation_index);
   return;
 }

test/var/initialization/workgroup/struct.wgsl.expected.msl

@@ -6,14 +6,18 @@ struct S {
   float b;
 };
 
-kernel void tint_symbol(uint local_invocation_index [[thread_index_in_threadgroup]]) {
-  threadgroup S tint_symbol_3;
+void tint_symbol_inner(uint local_invocation_index, threadgroup S* const tint_symbol_2) {
   {
-    S const tint_symbol_2 = {};
-    tint_symbol_3 = tint_symbol_2;
+    S const tint_symbol_1 = {};
+    *(tint_symbol_2) = tint_symbol_1;
   }
   threadgroup_barrier(mem_flags::mem_threadgroup);
-  (void) tint_symbol_3;
+  (void) *(tint_symbol_2);
+}
+
+kernel void tint_symbol(uint local_invocation_index [[thread_index_in_threadgroup]]) {
+  threadgroup S tint_symbol_3;
+  tint_symbol_inner(local_invocation_index, &(tint_symbol_3));
   return;
 }
 

test/var/initialization/workgroup/vector.wgsl.expected.hlsl

@@ -4,13 +4,16 @@ struct tint_symbol_1 {
   uint local_invocation_index : SV_GroupIndex;
 };
 
-[numthreads(1, 1, 1)]
-void main(tint_symbol_1 tint_symbol) {
-  const uint local_invocation_index = tint_symbol.local_invocation_index;
+void main_inner(uint local_invocation_index) {
   {
     v = int3(0, 0, 0);
   }
   GroupMemoryBarrierWithGroupSync();
   v;
+}
+
+[numthreads(1, 1, 1)]
+void main(tint_symbol_1 tint_symbol) {
+  main_inner(tint_symbol.local_invocation_index);
   return;
 }

test/var/initialization/workgroup/vector.wgsl.expected.msl

@@ -1,13 +1,17 @@
 #include <metal_stdlib>
 
 using namespace metal;
-kernel void tint_symbol(uint local_invocation_index [[thread_index_in_threadgroup]]) {
-  threadgroup int3 tint_symbol_2;
+void tint_symbol_inner(uint local_invocation_index, threadgroup int3* const tint_symbol_1) {
   {
-    tint_symbol_2 = int3();
+    *(tint_symbol_1) = int3();
   }
   threadgroup_barrier(mem_flags::mem_threadgroup);
-  (void) tint_symbol_2;
+  (void) *(tint_symbol_1);
+}
+
+kernel void tint_symbol(uint local_invocation_index [[thread_index_in_threadgroup]]) {
+  threadgroup int3 tint_symbol_2;
+  tint_symbol_inner(local_invocation_index, &(tint_symbol_2));
   return;
 }