shader: Partially implement texture cube array shadow

This implements texture cube arrays with shadow comparisons but doesn't
fix the asserts related to it.

Fixes out of bounds reads on swizzle constructors and makes them use
bounds checked ::at instead of the unsafe operator[].

3 files changed, 37 insertions, 25 deletions

diff --git a/src/video_core/renderer_opengl/gl_arb_decompiler.cpp b/src/video_core/renderer_opengl/gl_arb_decompiler.cpp
index f4db62787..d6120c23e 100644
--- a/src/video_core/renderer_opengl/gl_arb_decompiler.cpp
+++ b/src/video_core/renderer_opengl/gl_arb_decompiler.cpp
@@ -39,8 +39,8 @@ using Operation = const OperationNode&;
 constexpr std::array INTERNAL_FLAG_NAMES = {"ZERO", "SIGN", "CARRY", "OVERFLOW"};
 
 char Swizzle(std::size_t component) {
-    ASSERT(component < 4);
-    return component["xyzw"];
+    static constexpr std::string_view SWIZZLE{"xyzw"};
+    return SWIZZLE.at(component);
 }
 
 constexpr bool IsGenericAttribute(Attribute::Index index) {
@@ -224,7 +224,7 @@ private:
 
     std::string Visit(const Node& node);
 
-    std::pair<std::string, std::size_t> BuildCoords(Operation);
+    std::tuple<std::string, std::string, std::size_t> BuildCoords(Operation);
     std::string BuildAoffi(Operation);
     std::string GlobalMemoryPointer(const GmemNode& gmem);
     void Exit();
@@ -1416,12 +1416,12 @@ std::string ARBDecompiler::Visit(const Node& node) {
     return {};
 }
 
-std::pair<std::string, std::size_t> ARBDecompiler::BuildCoords(Operation operation) {
+std::tuple<std::string, std::string, std::size_t> ARBDecompiler::BuildCoords(Operation operation) {
     const auto& meta = std::get<MetaTexture>(operation.GetMeta());
     UNIMPLEMENTED_IF(meta.sampler.is_indexed);
-    UNIMPLEMENTED_IF(meta.sampler.is_shadow && meta.sampler.is_array &&
-                     meta.sampler.type == Tegra::Shader::TextureType::TextureCube);
 
+    const bool is_extended = meta.sampler.is_shadow && meta.sampler.is_array &&
+                             meta.sampler.type == Tegra::Shader::TextureType::TextureCube;
     const std::size_t count = operation.GetOperandsCount();
     std::string temporary = AllocVectorTemporary();
     std::size_t i = 0;
@@ -1429,12 +1429,21 @@ std::pair<std::string, std::size_t> ARBDecompiler::BuildCoords(Operation operati
         AddLine("MOV.F {}.{}, {};", temporary, Swizzle(i), Visit(operation[i]));
     }
     if (meta.sampler.is_array) {
-        AddLine("I2F.S {}.{}, {};", temporary, Swizzle(i++), Visit(meta.array));
+        AddLine("I2F.S {}.{}, {};", temporary, Swizzle(i), Visit(meta.array));
+        ++i;
     }
     if (meta.sampler.is_shadow) {
-        AddLine("MOV.F {}.{}, {};", temporary, Swizzle(i++), Visit(meta.depth_compare));
+        std::string compare = Visit(meta.depth_compare);
+        if (is_extended) {
+            ASSERT(i == 4);
+            std::string extra_coord = AllocVectorTemporary();
+            AddLine("MOV.F {}.x, {};", extra_coord, compare);
+            return {fmt::format("{}, {}", temporary, extra_coord), extra_coord, 0};
+        }
+        AddLine("MOV.F {}.{}, {};", temporary, Swizzle(i), compare);
+        ++i;
     }
-    return {std::move(temporary), i};
+    return {temporary, temporary, i};
 }
 
 std::string ARBDecompiler::BuildAoffi(Operation operation) {
@@ -1859,7 +1868,7 @@ std::string ARBDecompiler::LogicalAddCarry(Operation operation) {
 std::string ARBDecompiler::Texture(Operation operation) {
     const auto& meta = std::get<MetaTexture>(operation.GetMeta());
     const u32 sampler_id = device.GetBaseBindings(stage).sampler + meta.sampler.index;
-    const auto [temporary, swizzle] = BuildCoords(operation);
+    const auto [coords, temporary, swizzle] = BuildCoords(operation);
 
     std::string_view opcode = "TEX";
     std::string extra;
@@ -1888,7 +1897,7 @@ std::string ARBDecompiler::Texture(Operation operation) {
         }
     }
 
-    AddLine("{}.F {}, {},{} texture[{}], {}{};", opcode, temporary, temporary, extra, sampler_id,
+    AddLine("{}.F {}, {},{} texture[{}], {}{};", opcode, temporary, coords, extra, sampler_id,
             TextureType(meta), BuildAoffi(operation));
     AddLine("MOV.U {}.x, {}.{};", temporary, temporary, Swizzle(meta.element));
     return fmt::format("{}.x", temporary);
@@ -1897,7 +1906,7 @@ std::string ARBDecompiler::Texture(Operation operation) {
 std::string ARBDecompiler::TextureGather(Operation operation) {
     const auto& meta = std::get<MetaTexture>(operation.GetMeta());
     const u32 sampler_id = device.GetBaseBindings(stage).sampler + meta.sampler.index;
-    const auto [temporary, swizzle] = BuildCoords(operation);
+    const auto [coords, temporary, swizzle] = BuildCoords(operation);
 
     std::string comp;
     if (!meta.sampler.is_shadow) {
@@ -1907,7 +1916,7 @@ std::string ARBDecompiler::TextureGather(Operation operation) {
 
     AddLine("TXG.F {}, {}, texture[{}]{}, {}{};", temporary, temporary, sampler_id, comp,
             TextureType(meta), BuildAoffi(operation));
-    AddLine("MOV.U {}.x, {}.{};", temporary, temporary, Swizzle(meta.element));
+    AddLine("MOV.U {}.x, {}.{};", temporary, coords, Swizzle(meta.element));
     return fmt::format("{}.x", temporary);
 }
 
@@ -1945,13 +1954,13 @@ std::string ARBDecompiler::TextureQueryLod(Operation operation) {
 std::string ARBDecompiler::TexelFetch(Operation operation) {
     const auto& meta = std::get<MetaTexture>(operation.GetMeta());
     const u32 sampler_id = device.GetBaseBindings(stage).sampler + meta.sampler.index;
-    const auto [temporary, swizzle] = BuildCoords(operation);
+    const auto [coords, temporary, swizzle] = BuildCoords(operation);
 
     if (!meta.sampler.is_buffer) {
         ASSERT(swizzle < 4);
         AddLine("MOV.F {}.w, {};", temporary, Visit(meta.lod));
     }
-    AddLine("TXF.F {}, {}, texture[{}], {}{};", temporary, temporary, sampler_id, TextureType(meta),
+    AddLine("TXF.F {}, {}, texture[{}], {}{};", temporary, coords, sampler_id, TextureType(meta),
             BuildAoffi(operation));
     AddLine("MOV.U {}.x, {}.{};", temporary, temporary, Swizzle(meta.element));
     return fmt::format("{}.x", temporary);
@@ -1962,7 +1971,7 @@ std::string ARBDecompiler::TextureGradient(Operation operation) {
     const u32 sampler_id = device.GetBaseBindings(stage).sampler + meta.sampler.index;
     const std::string ddx = AllocVectorTemporary();
     const std::string ddy = AllocVectorTemporary();
-    const std::string coord = BuildCoords(operation).first;
+    const std::string coord = std::get<1>(BuildCoords(operation));
 
     const std::size_t num_components = meta.derivates.size() / 2;
     for (std::size_t index = 0; index < num_components; ++index) {
diff --git a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
index bbb8fb095..95ca96c8e 100644
--- a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
+++ b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
@@ -2056,15 +2056,19 @@ private:
     }
 
     Expression Texture(Operation operation) {
-        const auto meta = std::get_if<MetaTexture>(&operation.GetMeta());
-        ASSERT(meta);
-
-        std::string expr = GenerateTexture(
-            operation, "", {TextureOffset{}, TextureArgument{Type::Float, meta->bias}});
-        if (meta->sampler.is_shadow) {
-            expr = "vec4(" + expr + ')';
+        const auto meta = std::get<MetaTexture>(operation.GetMeta());
+        const bool separate_dc = meta.sampler.type == TextureType::TextureCube &&
+                                 meta.sampler.is_array && meta.sampler.is_shadow;
+        // TODO: Replace this with an array and make GenerateTexture use C++20 std::span
+        const std::vector<TextureIR> extras{
+            TextureOffset{},
+            TextureArgument{Type::Float, meta.bias},
+        };
+        std::string expr = GenerateTexture(operation, "", extras, separate_dc);
+        if (meta.sampler.is_shadow) {
+            expr = fmt::format("vec4({})", expr);
         }
-        return {expr + GetSwizzle(meta->element), Type::Float};
+        return {expr + GetSwizzle(meta.element), Type::Float};
     }
 
     Expression TextureLod(Operation operation) {
diff --git a/src/video_core/shader/decode/texture.cpp b/src/video_core/shader/decode/texture.cpp
index 4e932a4b6..02fdccd86 100644
--- a/src/video_core/shader/decode/texture.cpp
+++ b/src/video_core/shader/decode/texture.cpp
@@ -556,7 +556,6 @@ Node4 ShaderIR::GetTextureCode(Instruction instr, TextureType texture_type,
     const bool is_shadow = depth_compare != nullptr;
     const bool is_bindless = bindless_reg.has_value();
 
-    UNIMPLEMENTED_IF(texture_type == TextureType::TextureCube && is_array && is_shadow);
     ASSERT_MSG(texture_type != TextureType::Texture3D || !is_array || !is_shadow,
                "Illegal texture type");