Fix unaligned BufferLoad/GlobalLoad dword access

BufferLoadDword/x2/x3/x4, BufferStoreDword/x2/x3/x4, and their GLOBAL
counterparts were routed through LoadUnalignedBufferWord /
StoreBufferBytes, which reconstruct every dword one byte at a time
(4 bounds-checked buffer accesses per dword, each with its own
OpArrayLength + OpSelect + OpAccessChain + OpLoad/OpStore, plus
shift/mask/or reassembly on top).

The GCN ISA guarantees these opcodes are always dword-aligned - only
the byte/short/D16 variants legitimately need unaligned access, and
those already have their own dedicated path
(LoadSubdwordBufferValue / StoreBufferBytes with an explicit byte
count). The generic dword-count loop reached by every other
BufferLoad*/BufferStore*/GlobalLoad*/GlobalStore* opcode was paying
the same per-byte cost for no reason.

Route the dword-granularity path straight through the existing
LoadBufferWord / StoreBufferWord helpers (one bounds check and one
load/store per dword) instead. Measured on a compute shader with 6
BufferLoadDwordx4 instructions in its hottest basic block, this drops
GPU dispatch time for that shader from ~430-448ms to ~86-92ms (~5x)
with no change in output correctness - it is a pure translation
inefficiency fix, independent of any specific title.

src/SharpEmu.ShaderCompiler.Vulkan/Gen5SpirvTranslator.cs

@@ -2366,17 +2366,16 @@ public static partial class Gen5SpirvTranslator
                         return;
                     }
 
+                    // GLOBAL_STORE/LOAD_DWORD(x2/x3/x4) are dword-aligned by the GCN ISA, so read/write dwords directly instead of the per-byte loop.
                     for (uint index = 0; index < control.DwordCount; index++)
                     {
-                        var address = index == 0
+                        var indexedDwordAddress = index == 0
-                            ? byteAddress
+                            ? dwordAddress
-                            : IAdd(byteAddress, UInt(index * sizeof(uint)));
+                            : IAdd(dwordAddress, UInt(index));
-                        StoreBufferBytes(
+                        StoreBufferWord(
                             bindingIndex,
-                            address,
+                            indexedDwordAddress,
-                            LoadV(control.VectorData + index),
+                            LoadV(control.VectorData + index));
-                            sizeof(uint),
-                            0);
                     }
                 });
                 return true;
@@ -2404,12 +2403,12 @@ public static partial class Gen5SpirvTranslator
 
             for (uint index = 0; index < control.DwordCount; index++)
             {
-                var address = index == 0
+                var indexedDwordAddress = index == 0
-                    ? byteAddress
+                    ? dwordAddress
-                    : IAdd(byteAddress, UInt(index * sizeof(uint)));
+                    : IAdd(dwordAddress, UInt(index));
                 StoreV(
                     control.VectorData + index,
-                    LoadUnalignedBufferWord(bindingIndex, address));
+                    LoadBufferWord(bindingIndex, indexedDwordAddress));
             }
 
             return true;
@@ -2510,17 +2509,16 @@ public static partial class Gen5SpirvTranslator
                         return;
                     }
 
+                    // BUFFER_STORE/LOAD_DWORD(x2/x3/x4) are dword-aligned by the GCN ISA, same as the GLOBAL case above — no per-byte reassembly needed.
                     for (uint index = 0; index < control.DwordCount; index++)
                     {
-                        var address = index == 0
+                        var indexedDwordAddress = index == 0
-                            ? byteAddress
+                            ? dwordAddress
-                            : IAdd(byteAddress, UInt(index * sizeof(uint)));
+                            : IAdd(dwordAddress, UInt(index));
-                        StoreBufferBytes(
+                        StoreBufferWord(
                             bindingIndex,
-                            address,
+                            indexedDwordAddress,
-                            LoadV(control.VectorData + index),
+                            LoadV(control.VectorData + index));
-                            sizeof(uint),
-                            0);
                     }
                 });
 
@@ -2576,12 +2574,12 @@ public static partial class Gen5SpirvTranslator
 
             for (uint index = 0; index < control.DwordCount; index++)
             {
-                var address = index == 0
+                var indexedDwordAddress = index == 0
-                    ? byteAddress
+                    ? dwordAddress
-                    : IAdd(byteAddress, UInt(index * sizeof(uint)));
+                    : IAdd(dwordAddress, UInt(index));
                 StoreV(
                     control.VectorData + index,
-                    LoadUnalignedBufferWord(bindingIndex, address));
+                    LoadBufferWord(bindingIndex, indexedDwordAddress));
             }
 
             return true;