[shader_recompiler] Fix IsScaled dynamic indexing reading wrong bit source (#3789)

The non-immediate path in IsScaled was incorrectly using index_value as the source for OpBitFieldUExtract, instead of loading the corresponding word from the push constant bitmask.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3789
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Reviewed-by: crueter <crueter@eden-emu.dev>
Co-authored-by: MaranBr <maranbr@outlook.com>
Co-committed-by: MaranBr <maranbr@outlook.com>

src/shader_recompiler/backend/spirv/emit_spirv_image.cpp

@@ -285,8 +285,13 @@ Id IsScaled(EmitContext& ctx, const IR::Value& index, Id member_index, u32 base_
         if (base_index != 0) {
             index_value = ctx.OpIAdd(ctx.U32[1], index_value, ctx.Const(base_index));
         }
+        const Id word_index{ctx.OpShiftRightLogical(ctx.U32[1], index_value, ctx.Const(5u))};
         const Id bit_index{ctx.OpBitwiseAnd(ctx.U32[1], index_value, ctx.Const(31u))};
-        bit = ctx.OpBitFieldUExtract(ctx.U32[1], index_value, bit_index, ctx.Const(1u));
+        const Id pointer{ctx.OpAccessChain(push_constant_u32, ctx.rescaling_push_constants,
+                                           member_index, word_index)};
+        const Id word{ctx.OpLoad(ctx.U32[1], pointer)};
+        const Id bit_index_mask{ctx.OpShiftLeftLogical(ctx.U32[1], ctx.Const(1u), bit_index)};
+        bit = ctx.OpBitwiseAnd(ctx.U32[1], word, bit_index_mask);
     }
     return ctx.OpINotEqual(ctx.U1, bit, ctx.u32_zero_value);
 }