[ET-VK][ez] SDPA don't branch based on whether bounds check needed (#15600)

Title says it all!

Why?

* The branching path is causing incorrect output on Samsung S24. It's unclear what the exact underlying issue is but the problem is not reproducible on other GPUs and appears to be an issue specific to Adreno 750 architecture. To be safe, always use bounds checking.

Differential Revision: [D86226136](https://our.internmc.facebook.com/intern/diff/D86226136/)

Author: pytorchbot

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

@@ -119,55 +119,27 @@ void main() {
   }
   // Otherwise, need to actually compute output tile
   else {
-    const bool dont_check_bounds = (S - s) >= TILE_M &&
-        (context_len - c) >= TILE_N;
-
-    if (dont_check_bounds) {
-      for (int d4 = worker_id; d4 < D4; d4 += NUM_WORKERS_PER_OUT) {
-        load_q_projected_tile_no_checks(
-          q_tile,
-          d4,
-          s,
-          q_h,
-          D4,
-          Q_H,
-          S);
-
-        load_k_cache_tile_no_checks(
-          w_tile,
-          d4,
-          c,
-          kv_h,
-          D4,
-          context_len,
-          C,
-          KV_H);
-
-        fp_accumulate_with_fp_weight(out_tile, q_tile, w_tile);
-      }
-    } else {
-      for (int d4 = worker_id; d4 < D4; d4 += NUM_WORKERS_PER_OUT) {
-        load_q_projected_tile_with_checks(
-          q_tile,
-          d4,
-          s,
-          q_h,
-          D4,
-          Q_H,
-          S);
-
-        load_k_cache_tile_with_checks(
-          w_tile,
-          d4,
-          c,
-          kv_h,
-          D4,
-          context_len,
-          C,
-          KV_H);
-
-        fp_accumulate_with_fp_weight(out_tile, q_tile, w_tile);
-      }
+    for (int d4 = worker_id; d4 < D4; d4 += NUM_WORKERS_PER_OUT) {
+      load_q_projected_tile_with_checks(
+        q_tile,
+        d4,
+        s,
+        q_h,
+        D4,
+        Q_H,
+        S);
+
+      load_k_cache_tile_with_checks(
+        w_tile,
+        d4,
+        c,
+        kv_h,
+        D4,
+        context_len,
+        C,
+        KV_H);
+
+      fp_accumulate_with_fp_weight(out_tile, q_tile, w_tile);
     }
   }
 

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

@@ -130,55 +130,28 @@ void main() {
   }
   // Otherwise, need to actually compute output tile
   else {
-    const bool dont_check_bounds = (S - s) >= TILE_M &&
-        (context_len - c) >= TILE_N;
-
-    if (dont_check_bounds) {
-      for (int d4 = 0; d4 < D4; d4++) {
-        load_q_projected_tile_no_checks(
-          q_tile,
-          d4,
-          s,
-          q_h,
-          D4,
-          Q_H,
-          S);
-
-        load_k_cache_tile_no_checks(
-          w_tile,
-          d4,
-          c,
-          kv_h,
-          D4,
-          context_len,
-          C,
-          KV_H);
-
-        fp_accumulate_with_fp_weight(out_tile, q_tile, w_tile);
-      }
-    } else {
-      for (int d4 = 0; d4 < D4; d4++) {
-        load_q_projected_tile_with_checks(
-          q_tile,
-          d4,
-          s,
-          q_h,
-          D4,
-          Q_H,
-          S);
-
-        load_k_cache_tile_with_checks(
-          w_tile,
-          d4,
-          c,
-          kv_h,
-          D4,
-          context_len,
-          C,
-          KV_H);
-
-        fp_accumulate_with_fp_weight(out_tile, q_tile, w_tile);
-      }
+    for (int d4 = 0; d4 < D4; d4++) {
+      load_q_projected_tile_with_checks(
+        q_tile,
+        d4,
+        s,
+        q_h,
+        D4,
+        Q_H,
+        S);
+
+      load_k_cache_tile_with_checks(
+        w_tile,
+        d4,
+        c,
+        kv_h,
+        D4,
+        context_len,
+        C,
+        KV_H);
+
+
+      fp_accumulate_with_fp_weight(out_tile, q_tile, w_tile);
     }
 
     // Apply scale and mask