Avoid map/set double lookups

Fix some common anti-patterns with these data structures.

- You can dereference the iterator returned by `find` to access the
  underlying value directly, without an extra `operator[]`/`at`.
- Rather than checking for an element before insertion/deletion, you can
  just do the operation and if needed check the return value to
  determine if the insertion/deletion succeeded.

3 files changed, 12 insertions, 24 deletions

diff --git a/Source/Core/VideoCommon/GraphicsModSystem/Runtime/GraphicsModManager.cpp b/Source/Core/VideoCommon/GraphicsModSystem/Runtime/GraphicsModManager.cpp
index 0d070a4310..70d3a9a5ca 100644
--- a/Source/Core/VideoCommon/GraphicsModSystem/Runtime/GraphicsModManager.cpp
+++ b/Source/Core/VideoCommon/GraphicsModSystem/Runtime/GraphicsModManager.cpp
@@ -197,14 +197,13 @@ void GraphicsModManager::Load(const GraphicsModGroupConfig& config)
   {
     for (const GraphicsTargetGroupConfig& group : mod.m_groups)
     {
-      if (m_groups.contains(group.m_name))
+      if (const bool inserted = m_groups.insert(group.m_name).second; !inserted)
       {
         WARN_LOG_FMT(
             VIDEO,
             "Specified graphics mod group '{}' for mod '{}' is already specified by another mod.",
             group.m_name, mod.m_title);
       }
-      m_groups.insert(group.m_name);
 
       const auto internal_group = fmt::format("{}.{}", mod.m_title, group.m_name);
       for (const GraphicsTargetConfig& target : group.m_targets)
diff --git a/Source/Core/VideoCommon/ShaderCache.cpp b/Source/Core/VideoCommon/ShaderCache.cpp
index 0e5cc141a1..84b21f8e3d 100644
--- a/Source/Core/VideoCommon/ShaderCache.cpp
+++ b/Source/Core/VideoCommon/ShaderCache.cpp
@@ -1535,26 +1535,21 @@ const AbstractPipeline* ShaderCache::GetTextureReinterpretPipeline(TextureFormat
                                                                    TextureFormat to_format)
 {
   const auto key = std::make_pair(from_format, to_format);
-  auto iter = m_texture_reinterpret_pipelines.find(key);
-  if (iter != m_texture_reinterpret_pipelines.end())
+  const auto [iter, inserted] = m_texture_reinterpret_pipelines.emplace(key, nullptr);
+
+  if (!inserted)
     return iter->second.get();
 
   std::string shader_source =
       FramebufferShaderGen::GenerateTextureReinterpretShader(from_format, to_format);
   if (shader_source.empty())
-  {
-    m_texture_reinterpret_pipelines.emplace(key, nullptr);
     return nullptr;
-  }
 
   std::unique_ptr<AbstractShader> shader = g_gfx->CreateShaderFromSource(
       ShaderStage::Pixel, shader_source,
       fmt::format("Texture reinterpret pixel shader: {} to {}", from_format, to_format));
   if (!shader)
-  {
-    m_texture_reinterpret_pipelines.emplace(key, nullptr);
     return nullptr;
-  }
 
   AbstractPipelineConfig config;
   config.vertex_format = nullptr;
@@ -1566,8 +1561,8 @@ const AbstractPipeline* ShaderCache::GetTextureReinterpretPipeline(TextureFormat
   config.blending_state = RenderState::GetNoBlendingBlendState();
   config.framebuffer_state = RenderState::GetRGBA8FramebufferState();
   config.usage = AbstractPipelineUsage::Utility;
-  auto iiter = m_texture_reinterpret_pipelines.emplace(key, g_gfx->CreatePipeline(config));
-  return iiter.first->second.get();
+  iter->second = g_gfx->CreatePipeline(config);
+  return iter->second.get();
 }
 
 const AbstractShader*
@@ -1576,17 +1571,14 @@ ShaderCache::GetTextureDecodingShader(TextureFormat format,
 {
   const auto key = std::make_pair(static_cast<u32>(format),
                                   static_cast<u32>(palette_format.value_or(TLUTFormat::IA8)));
-  const auto iter = m_texture_decoding_shaders.find(key);
-  if (iter != m_texture_decoding_shaders.end())
+  const auto [iter, inserted] = m_texture_decoding_shaders.emplace(key, nullptr);
+  if (!inserted)
     return iter->second.get();
 
   const std::string shader_source =
       TextureConversionShaderTiled::GenerateDecodingShader(format, palette_format, APIType::OpenGL);
   if (shader_source.empty())
-  {
-    m_texture_decoding_shaders.emplace(key, nullptr);
     return nullptr;
-  }
 
   const std::string name =
       palette_format.has_value() ?
@@ -1596,12 +1588,9 @@ ShaderCache::GetTextureDecodingShader(TextureFormat format,
   std::unique_ptr<AbstractShader> shader =
       g_gfx->CreateShaderFromSource(ShaderStage::Compute, shader_source, name);
   if (!shader)
-  {
-    m_texture_decoding_shaders.emplace(key, nullptr);
     return nullptr;
-  }
 
-  const auto iiter = m_texture_decoding_shaders.emplace(key, std::move(shader));
-  return iiter.first->second.get();
+  iter->second = std::move(shader);
+  return iter->second.get();
 }
 }  // namespace VideoCommon
diff --git a/Source/Core/VideoCommon/TextureCacheBase.cpp b/Source/Core/VideoCommon/TextureCacheBase.cpp
index f58460e9ad..dc47eac86e 100644
--- a/Source/Core/VideoCommon/TextureCacheBase.cpp
+++ b/Source/Core/VideoCommon/TextureCacheBase.cpp
@@ -652,8 +652,8 @@ void TextureCacheBase::DoSaveState(PointerWrap& p)
 
       auto refpair1 = std::make_pair(*id1, *id2);
       auto refpair2 = std::make_pair(*id2, *id1);
-      if (!reference_pairs.contains(refpair1) && !reference_pairs.contains(refpair2))
-        reference_pairs.insert(refpair1);
+      if (!reference_pairs.contains(refpair2))
+        reference_pairs.insert(std::move(refpair1));
     }
   }