vulkan: optimize coopmat2 dequant functions (ggml-org#10855)

Change the code to do 16b loads when possible and extract the appropriate
component late, so the code is effectively decoding a pair of elements and
then selecting one. This can allow more commoning to happen in the compiler
when neighboring elements are loaded.

Author: jeffbolznv

ggml/src/ggml-vulkan/vulkan-shaders/dequant_funcs_cm2.comp

@@ -10,9 +10,10 @@ float16_t dequantFuncQ4_0(const in decodeBufQ4_0 bl, const in uint blockCoords[2
     const float16_t d = bl.block.d;
     const uint idx = coordInBlock[1];
     const uint shift = (idx & 0x10) >> 2;
-    uint32_t qs = unpack8(uint32_t(bl.block.qs[(idx & 0xE) >> 1]))[idx & 1];
+    uint32_t qs = uint32_t(bl.block.qs[(idx & 0xE) >> 1]);
     qs >>= shift;
-    qs &= 0xF;
+    qs &= 0x0F0F;
+    qs = unpack8(qs)[idx & 1];
     float16_t ret = (float16_t(qs) - float16_t(8)) * d;
     return ret;
 }
@@ -152,15 +153,17 @@ layout(buffer_reference, std430, buffer_reference_align = 16) buffer decodeBufQ4
    block_q4_K block;
 };
 
+layout(buffer_reference, std430, buffer_reference_align = 16) buffer decodeBufQ4_K_packed16 {
+   block_q4_K_packed16 block;
+};
+
 float16_t dequantFuncQ4_K(const in decodeBufQ4_K bl, const in uint blockCoords[2], const in uint coordInBlock[2])
 {
+    decodeBufQ4_K_packed16 bl16 = decodeBufQ4_K_packed16(bl);
     const uint idx = coordInBlock[1];
-    const uint iqs = idx;
 
-    const uint n = iqs / 64;                   // 0,1,2,3
-    const uint b = (iqs % 64) / 32;            // 0,1
+    const uint b = (idx & 0x20) >> 5;            // 0,1
     const uint is = (idx & 0xE0) >> 5;         // 0..7
-    const uint qsi = n * 32 + (iqs % 32);      // 0..127
 
     const f16vec2 loadd = bl.block.d;
 
@@ -184,9 +187,11 @@ float16_t dequantFuncQ4_K(const in decodeBufQ4_K bl, const in uint blockCoords[2
     const float16_t d = loadd.x * float16_t(sc);
     const float16_t m = loadd.y * float16_t(mbyte);
 
-    uint32_t dmask = 0xF << (b * 4);
+    uint qs = uint32_t(bl16.block.qs[((idx & 0xC0) >> 2) + ((idx & 0x1E) >> 1)]);
+    qs = (qs >> (b * 4)) & 0x0F0F;
+    qs = unpack8(qs)[idx & 1];
 
-    float16_t ret = d * float16_t((bl.block.qs[qsi    ] & dmask) >> (b * 4)) - m;
+    float16_t ret = d * float16_t(qs) - m;
 
     return ret;
 }
@@ -195,18 +200,19 @@ layout(buffer_reference, std430, buffer_reference_align = 16) buffer decodeBufQ5
    block_q5_K block;
 };
 
+layout(buffer_reference, std430, buffer_reference_align = 16) buffer decodeBufQ5_K_packed16 {
+   block_q5_K_packed16 block;
+};
+
 float16_t dequantFuncQ5_K(const in decodeBufQ5_K bl, const in uint blockCoords[2], const in uint coordInBlock[2])
 {
+    decodeBufQ5_K_packed16 bl16 = decodeBufQ5_K_packed16(bl);
     const uint idx = coordInBlock[1];
-    const uint iqs = idx;
 
-    const uint n = iqs / 64;                   // 0,1,2,3
-    const uint b = (iqs % 64) / 32;            // 0,1
+    const uint b = (idx & 0x20) >> 5;          // 0,1
     const uint is = (idx & 0xE0) >> 5;         // 0..7
-    const uint qsi = n * 32 + (iqs % 32);      // 0..127
-    const uint qhi = (iqs % 32);               // 0..31
 
-    const uint8_t hm = uint8_t(1 << (iqs / 32));
+    const uint32_t hm = 0x0101 << is;
 
     const f16vec2 loadd = bl.block.d;
 
@@ -230,9 +236,15 @@ float16_t dequantFuncQ5_K(const in decodeBufQ5_K bl, const in uint blockCoords[2
     const float16_t d = loadd.x * float16_t(sc);
     const float16_t m = loadd.y * float16_t(mbyte);
 
-    uint32_t dmask = 0xF << (b * 4);
+    uint qh = uint32_t(bl16.block.qh[(idx & 0x1E) >> 1]);
+    qh = qh & hm;
+    qh = unpack8(qh)[idx & 1];
 
-    float16_t ret = d * (float16_t((bl.block.qs[qsi    ] & dmask) >> (b * 4)) + float16_t((bl.block.qh[qhi    ] & hm) != 0 ? 16 : 0)) - m;
+    uint qs = uint32_t(bl16.block.qs[((idx & 0xC0) >> 2) + ((idx & 0x1E) >> 1)]);
+    qs = (qs >> (b * 4)) & 0x0F0F;
+    qs = unpack8(qs)[idx & 1];
+
+    float16_t ret = d * (float16_t(qs) + (qh != 0 ? float16_t(16) : float16_t(0))) - m;
 
     return ret;
 }
@@ -241,22 +253,30 @@ layout(buffer_reference, std430, buffer_reference_align = 2) buffer decodeBufQ6_
    block_q6_K block;
 };
 
+layout(buffer_reference, std430, buffer_reference_align = 16) buffer decodeBufQ6_K_packed16 {
+   block_q6_K_packed16 block;
+};
+
 float16_t dequantFuncQ6_K(const in decodeBufQ6_K bl, const in uint blockCoords[2], const in uint coordInBlock[2])
 {
+    decodeBufQ6_K_packed16 bl16 = decodeBufQ6_K_packed16(bl);
     const uint idx = coordInBlock[1];
-    const uint iqs = idx;
 
-    const uint n = iqs / 128;                   // 0,1
-    const uint b = (iqs % 128) / 64;            // 0,1
-    const uint is_b = (iqs % 32) / 16;          // 0,1
-    const uint qhshift = ((iqs % 128) / 32) * 2;// 0,2,4,6
-    const uint is = 8 * n + qhshift + is_b;     // 0..15
-    const uint qsi = n * 64 + (iqs % 64);       // 0..127
-    const uint qhi = n * 32 + (iqs % 32);       // 0..63
+    const uint b = (idx & 0x40) >> 6;           // 0,1
+    const uint qhshift = (idx & 0x60) >> 4;    // 0,2,4,6
+    const uint is = (idx & 0xF0) >> 4;          // 0..15
 
     const float16_t dscale = bl.block.d * float16_t(bl.block.scales[is]);
 
-    float16_t ret = dscale * float16_t(int8_t(((bl.block.ql[qsi    ] >> (b * 4)) & 0xF) | (((bl.block.qh[qhi    ] >> qhshift) & 3) << 4)) - 32);
+    uint ql = uint32_t(bl16.block.ql[((idx & 0x80) >> 2) + ((idx & 0x3E) >> 1)]);
+    ql = (ql >> (b * 4)) & 0x0F0F;
+
+    uint qh = uint32_t(bl16.block.qh[((idx & 0x80) >> 3) + ((idx & 0x1E) >> 1)]);
+    qh = ((qh >> qhshift) & 0x0303) << 4;
+
+    int q = unpack8(ql | qh)[idx & 1];
+
+    float16_t ret = dscale * float16_t(q - 32);
 
     return ret;
 }