From 018cd407d7ae5fe10dc7f3ccab815ac3dfaaaa91 Mon Sep 17 00:00:00 2001
From: Jeff Bolz <jbolz@nvidia.com>
Date: Fri, 21 Aug 2026 21:19:06 -0500
Subject: [PATCH] vulkan: combine duplicated fastdiv functions, rename the one
 optimizing small divs

---
 .../ggml-vulkan/vulkan-shaders/conv2d_mm.comp  |  9 +--------
 .../ggml-vulkan/vulkan-shaders/conv3d_mm.comp  |  9 +--------
 .../vulkan-shaders/generic_unary_head.glsl     | 14 ++------------
 .../ggml-vulkan/vulkan-shaders/glu_head.glsl   |  8 ++------
 .../ggml-vulkan/vulkan-shaders/sum_rows.glsl   | 10 ++--------
 ggml/src/ggml-vulkan/vulkan-shaders/utils.glsl | 18 +++++++++++++++---
 6 files changed, 23 insertions(+), 45 deletions(-)

diff --git a/ggml/src/ggml-vulkan/vulkan-shaders/conv2d_mm.comp b/ggml/src/ggml-vulkan/vulkan-shaders/conv2d_mm.comp
index 99400098bf2b..c64004cdc48e 100644
--- a/ggml/src/ggml-vulkan/vulkan-shaders/conv2d_mm.comp
+++ b/ggml/src/ggml-vulkan/vulkan-shaders/conv2d_mm.comp
@@ -19,6 +19,7 @@
 #endif
 
 #include "types.glsl"
+#include "utils.glsl"
 
 // shape notation: [dim(N), ..., dim(0)] -- stride(dim(j)) >= stride(dim(i)) if i > j
 layout(binding = 0) readonly buffer A {
@@ -193,14 +194,6 @@ uint32_t       Br    = tid / BS_NPQ;
 uint32_t       Bc    = tid % BS_NPQ;
 const uint32_t BrpWg = WG_SIZE / BS_NPQ;
 
-// see init_fastdiv_values in ggml-vulkan.cpp
-uint fastdiv(uint n, uint mp, uint L) {
-    uint msbs, lsbs;
-    // msbs = mulhi(n, mp)
-    umulExtended(n, mp, msbs, lsbs);
-    return (msbs + n) >> L;
-}
-
 #ifdef COOPMAT2
 #define ACC_TYPE float16_t
 
diff --git a/ggml/src/ggml-vulkan/vulkan-shaders/conv3d_mm.comp b/ggml/src/ggml-vulkan/vulkan-shaders/conv3d_mm.comp
index f66f299f6dae..d5ce4290b930 100644
--- a/ggml/src/ggml-vulkan/vulkan-shaders/conv3d_mm.comp
+++ b/ggml/src/ggml-vulkan/vulkan-shaders/conv3d_mm.comp
@@ -15,6 +15,7 @@
 #endif
 
 #include "types.glsl"
+#include "utils.glsl"
 
 // shape notation: [dim(N), ..., dim(0)] -- stride(dim(j)) >= stride(dim(i)) if i > j
 layout(binding = 0) readonly buffer A {
@@ -178,14 +179,6 @@ uint32_t       Br    = tid / BS_NPQ;
 uint32_t       Bc    = tid % BS_NPQ;
 const uint32_t BrpWg = WG_SIZE / BS_NPQ;
 
-// see init_fastdiv_values in ggml-vulkan.cpp
-uint fastdiv(uint n, uint mp, uint L) {
-    uint msbs, lsbs;
-    // msbs = mulhi(n, mp)
-    umulExtended(n, mp, msbs, lsbs);
-    return (msbs + n) >> L;
-}
-
 void split_crs(uint32_t crs_idx, out uint32_t ic, out uint32_t kd, out uint32_t kh, out uint32_t kw) {
     const uint32_t KHKW = KH * KW;
     const uint32_t KDKHKW = KD * KHKW;
diff --git a/ggml/src/ggml-vulkan/vulkan-shaders/generic_unary_head.glsl b/ggml/src/ggml-vulkan/vulkan-shaders/generic_unary_head.glsl
index 9d4176f3f967..e13de9a00f2f 100644
--- a/ggml/src/ggml-vulkan/vulkan-shaders/generic_unary_head.glsl
+++ b/ggml/src/ggml-vulkan/vulkan-shaders/generic_unary_head.glsl
@@ -1,6 +1,8 @@
 #extension GL_EXT_shader_16bit_storage : require
 #extension GL_EXT_control_flow_attributes : require
 
+#include "utils.glsl"
+
 layout (push_constant) uniform parameter
 {
     uint ne;
@@ -32,18 +34,6 @@ uint get_idx() {
 uint get_aoffset() { return p.misalign_offsets >> 16; }
 uint get_doffset() { return p.misalign_offsets & 0xFFFF; }
 
-// see init_fastdiv_values in ggml-vulkan.cpp
-uint fastdiv(uint n, uint mp, uint L) {
-    uint msbs, lsbs;
-    // msbs = mulhi(n, mp)
-    umulExtended(n, mp, msbs, lsbs);
-    return (msbs + n) >> L;
-}
-
-uint fastdiv_L(uint packed, uint slot) {
-    return (packed >> (slot * 8)) & 0x3Fu;
-}
-
 uint src0_idx(uint idx) {
     const uint i03 = fastdiv(idx, p.ne0_012mp, fastdiv_L(p.ne0_Ls, 0));
     const uint i03_offset = i03 * p.ne02*p.ne01*p.ne00;
diff --git a/ggml/src/ggml-vulkan/vulkan-shaders/glu_head.glsl b/ggml/src/ggml-vulkan/vulkan-shaders/glu_head.glsl
index c3cae736f977..fc2951ec2e56 100644
--- a/ggml/src/ggml-vulkan/vulkan-shaders/glu_head.glsl
+++ b/ggml/src/ggml-vulkan/vulkan-shaders/glu_head.glsl
@@ -1,5 +1,7 @@
 #extension GL_EXT_shader_16bit_storage : require
 
+#include "utils.glsl"
+
 
 layout(local_size_x = 512, local_size_y = 1, local_size_z = 1) in;
 
@@ -39,9 +41,3 @@ uint get_aoffset() { return p.misalign_offsets >> 16; }
 uint get_boffset() { return (p.misalign_offsets >> 8) & 0xFF; }
 uint get_doffset() { return p.misalign_offsets & 0xFF; }
 
-// see init_fastdiv_values in ggml-vulkan.cpp
-uint fastdiv(uint n, uint mp, uint L) {
-    uint msbs, lsbs;
-    umulExtended(n, mp, msbs, lsbs);
-    return (msbs + n) >> L;
-}
diff --git a/ggml/src/ggml-vulkan/vulkan-shaders/sum_rows.glsl b/ggml/src/ggml-vulkan/vulkan-shaders/sum_rows.glsl
index 2b841baa6bf2..1cb0f7827a38 100644
--- a/ggml/src/ggml-vulkan/vulkan-shaders/sum_rows.glsl
+++ b/ggml/src/ggml-vulkan/vulkan-shaders/sum_rows.glsl
@@ -1,4 +1,6 @@
 
+#include "utils.glsl"
+
 // vk_op_sum_rows_push_constants
 layout (push_constant) uniform parameter
 {
@@ -15,11 +17,3 @@ layout (push_constant) uniform parameter
 uint get_aoffset() { return p.misalign_offsets >> 16; }
 uint get_doffset() { return p.misalign_offsets & 0xFFFF; }
 
-// see init_fastdiv_values in ggml-vulkan.cpp
-uint fastdiv(uint n, uint mp, uint L) {
-    uint msbs, lsbs;
-    // msbs = mulhi(n, mp)
-    umulExtended(n, mp, msbs, lsbs);
-    return (msbs + n) >> L;
-}
-
diff --git a/ggml/src/ggml-vulkan/vulkan-shaders/utils.glsl b/ggml/src/ggml-vulkan/vulkan-shaders/utils.glsl
index dc4a1e6d96ba..8aac64d75932 100644
--- a/ggml/src/ggml-vulkan/vulkan-shaders/utils.glsl
+++ b/ggml/src/ggml-vulkan/vulkan-shaders/utils.glsl
@@ -9,14 +9,26 @@ uint fastmod(uint a, uint b) {
     return a % b;
 }
 
-uint fastdiv(uint a, uint b) {
+// see init_fastdiv_values in ggml-vulkan.cpp
+uint fastdiv(uint n, uint mp, uint L) {
+    uint msbs, lsbs;
+    // msbs = mulhi(n, mp)
+    umulExtended(n, mp, msbs, lsbs);
+    return (msbs + n) >> L;
+}
+
+uint fastdiv_L(uint packed, uint slot) {
+    return (packed >> (slot * 8)) & 0x3Fu;
+}
+
+uint fastdiv_small(uint a, uint b) {
     return (a < b) ? 0 : (a / b);
 }
 
 void get_indices(uint idx, out uint i00, out uint i01, out uint i02, out uint i03, uint ne00, uint ne01, uint ne02, uint ne03) {
-    i03 = fastdiv(idx, (ne02*ne01*ne00));
+    i03 = fastdiv_small(idx, (ne02*ne01*ne00));
     const uint i03_offset = i03 * ne02*ne01*ne00;
-    i02 = fastdiv((idx - i03_offset), (ne01*ne00));
+    i02 = fastdiv_small((idx - i03_offset), (ne01*ne00));
     const uint i02_offset = i02*ne01*ne00;
     i01 = (idx - i03_offset - i02_offset) / ne00;
     i00 = idx - i03_offset - i02_offset - i01*ne00;