vulkan: fix failing dequant shaders (#15862)

* vulkan: fix failing dequant shaders

* add missing const

ggml/src/ggml-vulkan/vulkan-shaders/dequant_iq2_s.comp

@@ -29,7 +29,7 @@ void main() {
         uint qs = data_a[ib].qs[4 * ib32 + l];
         const uint8_t sign = data_a[ib].qs[QUANT_K / 8 + 4 * ib32 + l];
         qs |= (qh << (8 - 2 * l)) & 0x300;
-        const uvec2 grid = iq2s_grid[qs & 511];
+        const uvec2 grid = iq2s_grid[qs];
         const u8vec4 grid0 = unpack8(grid.x);
         const u8vec4 grid1 = unpack8(grid.y);
         data_b[b_idx + 8 * l + 0] = D_TYPE(db[l/2] * grid0.x * ((sign & 1) != 0 ? -1.0 : 1.0));

ggml/src/ggml-vulkan/vulkan-shaders/dequant_iq2_xxs.comp

@@ -33,7 +33,8 @@ void main() {
     [[unroll]] for (uint l = 0; l < 4; ++l) {
         const uint sign7 = bitfieldExtract(signscale, 7 * int(l), 7);
         const uint sign8 = sign7 | (bitCount(sign7) << 7); // parity bit
-        const uvec2 grid = iq2xxs_grid[data_a[ib].qs[8 * is + l]];
+        const uint qs = data_a[ib].qs[8 * is + l];
+        const uvec2 grid = iq2xxs_grid[qs];
         const u8vec4 grid0 = unpack8(grid.x);
         const u8vec4 grid1 = unpack8(grid.y);
         data_b[b_idx + 8 * l + 0] = D_TYPE(db * grid0.x * ((sign8 & 1) != 0 ? -1.0 : 1.0));

ggml/src/ggml-vulkan/vulkan-shaders/dequant_iq3_s.comp

@@ -22,15 +22,16 @@ void main() {
     const uint b_idx = 256 * ib + 32 * is;
 
     const float d = float(data_a[ib].d);
-    const float db = d * (1 + 2 * ((data_a[ib].scales[is] >> (4 * (is % 2))) & 0xf));
+    const float db = d * (1 + 2 * ((data_a[ib].scales[is / 2] >> (4 * (is % 2))) & 0xf));
 
     // We must produce 32 values using 4 sign bytes, 1 qh byte, 8 qs bytes.
     uint qh = data_a[ib].qh[is];
     [[unroll]] for (uint l = 0; l < 8; ++l) {
-        uint qs = data_a[ib].qs[8 * is + l];
-        uint gidx = qs | ((qh << (8 - l)) & 256);
-        uint8_t signs = data_a[ib].signs[8 * is + l / 2] >> (4 * (l & 1));
-        u8vec4 grid = unpack8(iq3s_grid[gidx]);
+        const uint iqs = 8 * is + l;
+        const uint qs = data_a[ib].qs[iqs];
+        const uint gidx = qs | ((qh << (8 - l)) & 256);
+        const uint8_t signs = data_a[ib].signs[iqs / 2] >> (4 * (l & 1));
+        const u8vec4 grid = unpack8(iq3s_grid[gidx]);
         data_b[b_idx + 4 * l + 0] = D_TYPE(db * grid.x * ((signs & 1) != 0 ? -1.0 : 1.0));
         data_b[b_idx + 4 * l + 1] = D_TYPE(db * grid.y * ((signs & 2) != 0 ? -1.0 : 1.0));
         data_b[b_idx + 4 * l + 2] = D_TYPE(db * grid.z * ((signs & 4) != 0 ? -1.0 : 1.0));

ggml/src/ggml-vulkan/vulkan-shaders/dequant_iq3_xxs.comp

@@ -35,8 +35,10 @@ void main() {
         const uint sign7 = bitfieldExtract(signscale, 7 * int(l), 7);
         // Restore parity bit.
         const uint sign8 = sign7 | (bitCount(sign7) << 7);
-        const u8vec4 grid0 = unpack8(iq3xxs_grid[data_a[ib].qs[8 * is + 2 * l]]);
-        const u8vec4 grid1 = unpack8(iq3xxs_grid[data_a[ib].qs[8 * is + 2 * l + 1]]);
+        const uint qs0 = data_a[ib].qs[8 * is + 2 * l];
+        const uint qs1 = data_a[ib].qs[8 * is + 2 * l + 1];
+        const u8vec4 grid0 = unpack8(iq3xxs_grid[qs0]);
+        const u8vec4 grid1 = unpack8(iq3xxs_grid[qs1]);
         data_b[b_idx + 8 * l + 0] = D_TYPE(db * grid0.x * ((sign8 & 1) != 0 ? -1.0 : 1.0));
         data_b[b_idx + 8 * l + 1] = D_TYPE(db * grid0.y * ((sign8 & 2) != 0 ? -1.0 : 1.0));
         data_b[b_idx + 8 * l + 2] = D_TYPE(db * grid0.z * ((sign8 & 4) != 0 ? -1.0 : 1.0));