rhi: Returns mapping tables by value from QShader

As these are QList and QHash. All existing usages are based on this
anyway, no value in being able to indicate "not available" - an empty
container fulfills the same role.

Change-Id: I8059025fa7a4acb6fc674cd98b16fcafa19ed85d
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

5 files changed, 26 insertions, 31 deletions

diff --git a/src/gui/rhi/qrhid3d11.cpp b/src/gui/rhi/qrhid3d11.cpp
index 74abfdff87..eaaf0c6991 100644
--- a/src/gui/rhi/qrhid3d11.cpp
+++ b/src/gui/rhi/qrhid3d11.cpp
@@ -4156,8 +4156,7 @@ bool QD3D11GraphicsPipeline::create()
                     return false;
                 }
                 vsByteCode = bytecode;
-                if (const QShader::NativeResourceBindingMap *map = shaderStage.shader().nativeResourceBindingMap(shaderKey))
-                    vs.nativeResourceBindingMap = *map;
+                vs.nativeResourceBindingMap = shaderStage.shader().nativeResourceBindingMap(shaderKey);
                 rhiD->m_shaderCache.insert(shaderStage, QRhiD3D11::Shader(vs.shader, bytecode, vs.nativeResourceBindingMap));
                 vs.shader->AddRef();
                 break;
@@ -4167,8 +4166,7 @@ bool QD3D11GraphicsPipeline::create()
                     qWarning("Failed to create pixel shader: %s", qPrintable(comErrorMessage(hr)));
                     return false;
                 }
-                if (const QShader::NativeResourceBindingMap *map = shaderStage.shader().nativeResourceBindingMap(shaderKey))
-                    fs.nativeResourceBindingMap = *map;
+                fs.nativeResourceBindingMap = shaderStage.shader().nativeResourceBindingMap(shaderKey);
                 rhiD->m_shaderCache.insert(shaderStage, QRhiD3D11::Shader(fs.shader, bytecode, fs.nativeResourceBindingMap));
                 fs.shader->AddRef();
                 break;
@@ -4286,8 +4284,7 @@ bool QD3D11ComputePipeline::create()
             return false;
         }
 
-        if (const QShader::NativeResourceBindingMap *map = m_shaderStage.shader().nativeResourceBindingMap(shaderKey))
-            cs.nativeResourceBindingMap = *map;
+        cs.nativeResourceBindingMap = m_shaderStage.shader().nativeResourceBindingMap(shaderKey);
 
         if (rhiD->m_shaderCache.count() >= QRhiD3D11::MAX_SHADER_CACHE_ENTRIES)
             rhiD->clearShaderCache();
diff --git a/src/gui/rhi/qrhigles2.cpp b/src/gui/rhi/qrhigles2.cpp
index 02fbb5ec40..b67f87ed6e 100644
--- a/src/gui/rhi/qrhigles2.cpp
+++ b/src/gui/rhi/qrhigles2.cpp
@@ -5341,14 +5341,14 @@ bool QGles2GraphicsPipeline::create()
         if (shaderStage.type() == QRhiShaderStage::Vertex) {
             vsDesc = shader.description();
             if (!rhiD->shaderSource(shaderStage, &glslVersion).isEmpty()) {
-                if (auto *m = shader.separateToCombinedImageSamplerMappingList({ QShader::GlslShader, glslVersion, shaderStage.shaderVariant() }))
-                    vsSamplerMappingList = *m;
+                vsSamplerMappingList = shader.separateToCombinedImageSamplerMappingList(
+                            { QShader::GlslShader, glslVersion, shaderStage.shaderVariant() });
             }
         } else if (shaderStage.type() == QRhiShaderStage::Fragment) {
             fsDesc = shader.description();
             if (!rhiD->shaderSource(shaderStage, &glslVersion).isEmpty()) {
-                if (auto *m = shader.separateToCombinedImageSamplerMappingList({ QShader::GlslShader, glslVersion, shaderStage.shaderVariant() }))
-                    fsSamplerMappingList = *m;
+                fsSamplerMappingList = shader.separateToCombinedImageSamplerMappingList(
+                            { QShader::GlslShader, glslVersion, shaderStage.shaderVariant() });
             }
         }
     }
@@ -5484,8 +5484,8 @@ bool QGles2ComputePipeline::create()
     QShader::SeparateToCombinedImageSamplerMappingList csSamplerMappingList;
     int glslVersion = 0;
     if (!rhiD->shaderSource(m_shaderStage, &glslVersion).isEmpty()) {
-        if (auto *m = m_shaderStage.shader().separateToCombinedImageSamplerMappingList({ QShader::GlslShader, glslVersion, m_shaderStage.shaderVariant() }))
-            csSamplerMappingList = *m;
+        csSamplerMappingList = m_shaderStage.shader().separateToCombinedImageSamplerMappingList(
+                    { QShader::GlslShader, glslVersion, m_shaderStage.shaderVariant() });
     }
 
     program = rhiD->f->glCreateProgram();
diff --git a/src/gui/rhi/qrhimetal.mm b/src/gui/rhi/qrhimetal.mm
index 3a1eaccc92..ff136debe9 100644
--- a/src/gui/rhi/qrhimetal.mm
+++ b/src/gui/rhi/qrhimetal.mm
@@ -3642,8 +3642,7 @@ bool QMetalGraphicsPipeline::create()
             case QRhiShaderStage::Vertex:
                 d->vs.lib = lib;
                 d->vs.func = func;
-                if (const QShader::NativeResourceBindingMap *map = shader.nativeResourceBindingMap(activeKey))
-                    d->vs.nativeResourceBindingMap = *map;
+                d->vs.nativeResourceBindingMap = shader.nativeResourceBindingMap(activeKey);
                 rhiD->d->shaderCache.insert(shaderStage, d->vs);
                 [d->vs.lib retain];
                 [d->vs.func retain];
@@ -3652,8 +3651,7 @@ bool QMetalGraphicsPipeline::create()
             case QRhiShaderStage::Fragment:
                 d->fs.lib = lib;
                 d->fs.func = func;
-                if (const QShader::NativeResourceBindingMap *map = shader.nativeResourceBindingMap(activeKey))
-                    d->fs.nativeResourceBindingMap = *map;
+                d->fs.nativeResourceBindingMap = shader.nativeResourceBindingMap(activeKey);
                 rhiD->d->shaderCache.insert(shaderStage, d->fs);
                 [d->fs.lib retain];
                 [d->fs.func retain];
@@ -3810,8 +3808,7 @@ bool QMetalComputePipeline::create()
         d->cs.lib = lib;
         d->cs.func = func;
         d->cs.localSize = shader.description().computeShaderLocalSize();
-        if (const QShader::NativeResourceBindingMap *map = shader.nativeResourceBindingMap(activeKey))
-            d->cs.nativeResourceBindingMap = *map;
+        d->cs.nativeResourceBindingMap = shader.nativeResourceBindingMap(activeKey);
 
         if (rhiD->d->shaderCache.count() >= QRhiMetal::MAX_SHADER_CACHE_ENTRIES) {
             for (QMetalShader &s : rhiD->d->shaderCache)
diff --git a/src/gui/rhi/qshader.cpp b/src/gui/rhi/qshader.cpp
index b29abe2778..7c77803f12 100644
--- a/src/gui/rhi/qshader.cpp
+++ b/src/gui/rhi/qshader.cpp
@@ -742,16 +742,17 @@ QDebug operator<<(QDebug dbg, const QShaderVersion &v)
 */
 
 /*!
-    \return the native binding map for \a key or null if no extra mapping is
-    available, or is not applicable.
+    \return the native binding map for \a key. The map is empty if no mapping
+    is available for \a key (for example, because the map is not applicable for
+    the API and shading language described by \a key).
  */
-const QShader::NativeResourceBindingMap *QShader::nativeResourceBindingMap(const QShaderKey &key) const
+QShader::NativeResourceBindingMap QShader::nativeResourceBindingMap(const QShaderKey &key) const
 {
     auto it = d->bindings.constFind(key);
     if (it == d->bindings.cend())
-        return nullptr;
+        return {};
 
-    return &it.value();
+    return it.value();
 }
 
 /*!
@@ -798,17 +799,17 @@ void QShader::removeResourceBindingMap(const QShaderKey &key)
  */
 
 /*!
-    \return the combined image sampler mapping list for \a key or null if there
-    is no data available for \a key, for example because such a mapping is not
-    applicable for the shading language.
+    \return the combined image sampler mapping list for \a key, or an empty
+    list if there is no data available for \a key, for example because such a
+    mapping is not applicable for the shading language.
  */
-const QShader::SeparateToCombinedImageSamplerMappingList *QShader::separateToCombinedImageSamplerMappingList(const QShaderKey &key) const
+QShader::SeparateToCombinedImageSamplerMappingList QShader::separateToCombinedImageSamplerMappingList(const QShaderKey &key) const
 {
     auto it = d->combinedImageMap.constFind(key);
     if (it == d->combinedImageMap.cend())
-        return nullptr;
+        return {};
 
-    return &it.value();
+    return it.value();
 }
 
 /*!
diff --git a/src/gui/rhi/qshader_p.h b/src/gui/rhi/qshader_p.h
index 6dca86b1c4..29235c6b0b 100644
--- a/src/gui/rhi/qshader_p.h
+++ b/src/gui/rhi/qshader_p.h
@@ -163,7 +163,7 @@ public:
     static QShader fromSerialized(const QByteArray &data);
 
     using NativeResourceBindingMap = QHash<int, QPair<int, int> >; // binding -> native_binding[, native_binding]
-    const NativeResourceBindingMap *nativeResourceBindingMap(const QShaderKey &key) const;
+    NativeResourceBindingMap nativeResourceBindingMap(const QShaderKey &key) const;
     void setResourceBindingMap(const QShaderKey &key, const NativeResourceBindingMap &map);
     void removeResourceBindingMap(const QShaderKey &key);
 
@@ -173,7 +173,7 @@ public:
         int samplerBinding;
     };
     using SeparateToCombinedImageSamplerMappingList = QList<SeparateToCombinedImageSamplerMapping>;
-    const SeparateToCombinedImageSamplerMappingList *separateToCombinedImageSamplerMappingList(const QShaderKey &key) const;
+    SeparateToCombinedImageSamplerMappingList separateToCombinedImageSamplerMappingList(const QShaderKey &key) const;
     void setSeparateToCombinedImageSamplerMappingList(const QShaderKey &key,
                                                       const SeparateToCombinedImageSamplerMappingList &list);
     void removeSeparateToCombinedImageSamplerMappingList(const QShaderKey &key);