Rhi: improve qHash implementations

Use the combiners and an algorithm.

Change-Id: I577950bbd2e8b0556f28e2a8381e432c22bb0dc9
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

2 files changed, 26 insertions, 5 deletions

diff --git a/src/gui/rhi/qshader.cpp b/src/gui/rhi/qshader.cpp
index 18d0fdef05..2c1b333259 100644
--- a/src/gui/rhi/qshader.cpp
+++ b/src/gui/rhi/qshader.cpp
@@ -545,10 +545,12 @@ bool operator==(const QShader &lhs, const QShader &rhs) Q_DECL_NOTHROW
  */
 size_t qHash(const QShader &s, size_t seed) Q_DECL_NOTHROW
 {
-    size_t h = s.stage();
-    for (auto it = s.d->shaders.constBegin(), itEnd = s.d->shaders.constEnd(); it != itEnd; ++it)
-        h += qHash(it.key(), seed) + qHash(it.value().shader(), seed);
-    return h;
+    QtPrivate::QHashCombine hash;
+    seed = hash(seed, s.stage());
+    seed = qHashRange(s.d->shaders.keyValueBegin(),
+                      s.d->shaders.keyValueEnd(),
+                      seed);
+    return seed;
 }
 
 /*!
@@ -598,7 +600,11 @@ bool operator==(const QShaderKey &lhs, const QShaderKey &rhs) Q_DECL_NOTHROW
  */
 size_t qHash(const QShaderKey &k, size_t seed) Q_DECL_NOTHROW
 {
-    return seed + 10 * k.source() + k.sourceVersion().version() + k.sourceVersion().flags() + k.sourceVariant();
+    return qHashMulti(seed,
+                      k.source(),
+                      k.sourceVersion().version(),
+                      k.sourceVersion().flags(),
+                      k.sourceVariant());
 }
 
 /*!
@@ -620,6 +626,16 @@ bool operator==(const QShaderCode &lhs, const QShaderCode &rhs) Q_DECL_NOTHROW
     \relates QShaderCode
  */
 
+/*!
+    Returns the hash value for \a k, using \a seed to seed the calculation.
+
+    \relates QShaderCode
+ */
+size_t qHash(const QShaderCode &k, size_t seed) noexcept
+{
+    return qHash(k.shader(), seed);
+}
+
 #ifndef QT_NO_DEBUG_STREAM
 QDebug operator<<(QDebug dbg, const QShader &bs)
 {
diff --git a/src/gui/rhi/qshader_p.h b/src/gui/rhi/qshader_p.h
index f2d3c4ac2f..449873412f 100644
--- a/src/gui/rhi/qshader_p.h
+++ b/src/gui/rhi/qshader_p.h
@@ -81,6 +81,9 @@ private:
 Q_DECLARE_OPERATORS_FOR_FLAGS(QShaderVersion::Flags)
 Q_DECLARE_TYPEINFO(QShaderVersion, Q_MOVABLE_TYPE);
 
+class QShaderCode;
+Q_GUI_EXPORT size_t qHash(const QShaderCode &, size_t = 0) noexcept;
+
 class Q_GUI_EXPORT QShaderCode
 {
 public:
@@ -94,6 +97,8 @@ public:
     void setEntryPoint(const QByteArray &entry) { m_entryPoint = entry; }
 
 private:
+    friend Q_GUI_EXPORT size_t qHash(const QShaderCode &, size_t) noexcept;
+
     QByteArray m_shader;
     QByteArray m_entryPoint;
 };