From 952df1df05c8fed49fabe66a8556539bcb7a59d9 Mon Sep 17 00:00:00 2001
From: Eric A Stalee <87948564+Eric-A-Stalee@users.noreply.github.com>
Date: Thu, 27 Aug 2026 10:15:27 -0500
Subject: [PATCH 1/3] vulkan: fix missing view-alias dependencies in
 ggml_vk_graph_optimize

is_src_of doesn't treat two views of one tensor as dependent, so the optimizer reorders nodes across aliased reads and writes.

Result: silently wrong tokens under greedy decoding, different output on every server start, and invalid speculative-decoding acceptance, with nothing logged.

Hits Qwen3.8's recurrent state (and any model with view-aliased state) on AMD and NVIDIA Vulkan.  CUDA is clean.

Compare view_src bases on both sides.

Fixes #27805
---
 ggml/src/ggml-vulkan/ggml-vulkan.cpp | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/ggml/src/ggml-vulkan/ggml-vulkan.cpp b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
index 72e844aebfd5..082f1e80c481 100644
--- a/ggml/src/ggml-vulkan/ggml-vulkan.cpp
+++ b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
@@ -17779,15 +17779,24 @@ static void ggml_vk_graph_optimize(ggml_backend_t backend, struct ggml_cgraph *
     };
 
     auto const &is_src_of = [](const ggml_tensor *dst, const ggml_tensor *src) -> bool {
+        auto const &base = [](const ggml_tensor * tensor) {
+            return tensor->view_src ? tensor->view_src : tensor;
+        };
         for (uint32_t s = 0; s < GGML_MAX_SRC; ++s) {
             if (dst->src[s] == src) {
                 return true;
             }
+            // A source view of dst may read storage written through a different view by src.
+            if (dst->src[s] && base(dst->src[s]) == base(src)) {
+                return true;
+            }
+            // Moving dst forward may overwrite storage still read through a view by src.
+            if (src->src[s] && base(dst) == base(src->src[s])) {
+                return true;
+            }
         }
         // implicit dependency if they view the same tensor
-        const ggml_tensor *dst2 = dst->view_src ? dst->view_src : dst;
-        const ggml_tensor *src2 = src->view_src ? src->view_src : src;
-        if (dst2 == src2) {
+        if (base(dst) == base(src)) {
             return true;
         }
         return false;

From fcb381e2211a6c427d58f860ee703c0f7d3b9940 Mon Sep 17 00:00:00 2001
From: Eric A Stalee <87948564+Eric-A-Stalee@users.noreply.github.com>
Date: Fri, 28 Aug 2026 12:53:28 +0800
Subject: [PATCH 2/3] vulkan: don't treat view/no-op nodes as aliasing
 dependencies

Nodes whose op is NONE, RESHAPE, TRANSPOSE, VIEW or PERMUTE execute nothing, so aliasing through them is not a real dependency. The previous base comparison matched them anyway, which only costs the optimizer reordering freedom.

Co-authored-by: Jeff Bolz <jbolz@nvidia.com>
---
 ggml/src/ggml-vulkan/ggml-vulkan.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/ggml/src/ggml-vulkan/ggml-vulkan.cpp b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
index 082f1e80c481..203f820b9619 100644
--- a/ggml/src/ggml-vulkan/ggml-vulkan.cpp
+++ b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
@@ -17786,6 +17786,9 @@ static void ggml_vk_graph_optimize(ggml_backend_t backend, struct ggml_cgraph *
             if (dst->src[s] == src) {
                 return true;
             }
+            if (is_empty(dst) || is_empty(src)) {
+                continue;
+            }
             // A source view of dst may read storage written through a different view by src.
             if (dst->src[s] && base(dst->src[s]) == base(src)) {
                 return true;

From c6ba533382f67925367f02db880c86f6aae90e76 Mon Sep 17 00:00:00 2001
From: Eric A Stalee <87948564+Eric-A-Stalee@users.noreply.github.com>
Date: Fri, 28 Aug 2026 00:28:43 -0500
Subject: [PATCH 3/3] vulkan: make the lambda parameter const and capture
 is_empty in is_src_of

Code will not compile without these changes.
is_src_of has an empty capture list, so is_empty was not visible inside it, and is_empty took a non-const pointer, while is_src_of receives const ones. Other call sites pass non-const pointers, which still convert as usual.
---
 ggml/src/ggml-vulkan/ggml-vulkan.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ggml/src/ggml-vulkan/ggml-vulkan.cpp b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
index 203f820b9619..bb7aea13e619 100644
--- a/ggml/src/ggml-vulkan/ggml-vulkan.cpp
+++ b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
@@ -17774,11 +17774,11 @@ static void ggml_vk_graph_optimize(ggml_backend_t backend, struct ggml_cgraph *
         return;
     }
 
-    auto const &is_empty = [](ggml_tensor * node) -> bool {
+    auto const &is_empty = [](const ggml_tensor * node) -> bool {
         return node->op == GGML_OP_NONE || node->op == GGML_OP_RESHAPE || node->op == GGML_OP_TRANSPOSE || node->op == GGML_OP_VIEW || node->op == GGML_OP_PERMUTE;
     };
 
-    auto const &is_src_of = [](const ggml_tensor *dst, const ggml_tensor *src) -> bool {
+    auto const &is_src_of = [&is_empty](const ggml_tensor *dst, const ggml_tensor *src) -> bool {
         auto const &base = [](const ggml_tensor * tensor) {
             return tensor->view_src ? tensor->view_src : tensor;
         };