[ET-VK] Using vec2 to store output positions to reudce shader register footprint. (#7502)

* [ET-VK] Reduced int precision for all int storage in conv pw op to improve performance.

Pull Request resolved: #7447

This diff reduces the precision of all int storage in the conv pw op to improve performance. The code changes include adding the extension GL_EXT_shader_explicit_arithmetic_types_int16 and changing the data type of ints to uint16.

ghstack-source-id: 260166244
@exported-using-ghexport

Differential Revision: [D67674212](https://our.internmc.facebook.com/intern/diff/D67674212/)

* [ET-VK] Minor fix to conv 2d op using wg_size from create_conv2d_global_wg_size to determine local wg size.

Pull Request resolved: #7450

This diff contains changes to the Convolution.cpp file in the Vulkan backend of Executorch. The changes involve updating the code to use the create_conv2d_global_wg_size function to determine the local workgroup size for the convolution operation. This is done to ensure that the correct workgroup size is used for the operation, which can improve performance.

ghstack-source-id: 260166246
@exported-using-ghexport

Differential Revision: [D67676422](https://our.internmc.facebook.com/intern/diff/D67676422/)

* [ET-VK] Modify conv 2d pw op shader and dispatch settings to linearly dispatch work accounting for linearity texture to improve performance.

Pull Request resolved: #7452

This diff modifies the convolution 2D pointwise op shader and dispatch settings to linearly dispatch work accounting for linearity texture to improve performance.
ghstack-source-id: 260166247
@exported-using-ghexport

Differential Revision: [D67683411](https://our.internmc.facebook.com/intern/diff/D67683411/)

* [ET-VK] Using vec2 to store output positions to reudce shader register footprint.

Pull Request resolved: #7474

The diff changes the use of `u16vec3` to `u16vec2` to store output positions in the conv2d_pw op. This change is made to reduce the shader register footprint and improve performance.
ghstack-source-id: 260166245
@exported-using-ghexport

Differential Revision: [D67726229](https://our.internmc.facebook.com/intern/diff/D67726229/)

---------

Co-authored-by: Vivek Trivedi <5340687+trivedivivek@users.noreply.github.com>

Author: pytorchbot

backends/vulkan/runtime/graph/ops/glsl/conv2d_pw.glsl

@@ -53,18 +53,18 @@ void main() {
   // +--------+--------+
   // | pos[2] | pos[3] |
   // +--------+--------+
-  u16vec3 pos[TILE_SIZE * TILE_SIZE];
+  u16vec2 pos[TILE_SIZE * TILE_SIZE];
   for (int y = 0, i = 0; y < TILE_SIZE; ++y) {
     for (int x = 0; x < TILE_SIZE; ++x) {
-      pos[i] = u16vec3(
-          gpos.x * TILE_SIZE + x, gpos.y * TILE_SIZE + y, gpos.z);
+      pos[i] = u16vec2(
+          gpos.x * TILE_SIZE + x, gpos.y * TILE_SIZE + y);
       i++;
     }
   }
 
   // If the top left position is out of bounds, then this invocation will have
   // no work to do.
-  if (any(greaterThanEqual(pos[0], out_limits))) {
+  if (any(greaterThanEqual(u16vec3(pos[0], gpos.z), out_limits))) {
     return;
   }
 
@@ -138,8 +138,8 @@ void main() {
   }
 
   for (int i = 0; i < TILE_SIZE * TILE_SIZE; ++i) {
-    if (all(lessThan(pos[i], out_limits))) {
-      imageStore(t_out, pos[i], op(sum[i], out_min, out_max));
+    if (all(lessThan(u16vec3(pos[i], gpos.z), out_limits))) {
+      imageStore(t_out, u16vec3(pos[i], gpos.z), op(sum[i], out_min, out_max));
     }
   }
 }