From 89f7389494c6fc917f189150e06ed1fcfaa238e8 Mon Sep 17 00:00:00 2001
From: Laszlo Agocs <laszlo.agocs@qt.io>
Date: Fri, 25 Sep 2020 12:51:47 +0200
Subject: rhi: gl: d3d: Do not use QByteArray where there is no point

The real benefit in practice is getting rid of profilers going wild
about QByteArray::begin() and similar. The actual perf. gain is
fairly small.

Change-Id: I25e4c762f303b41f0aaf914bc62751f3265d3cf8
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
---
 src/gui/rhi/qrhid3d11.cpp | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

(limited to 'src/gui/rhi/qrhid3d11.cpp')

diff --git a/src/gui/rhi/qrhid3d11.cpp b/src/gui/rhi/qrhid3d11.cpp
index e924966585..2dc5763bd9 100644
--- a/src/gui/rhi/qrhid3d11.cpp
+++ b/src/gui/rhi/qrhid3d11.cpp
@@ -1418,7 +1418,7 @@ void QRhiD3D11::enqueueResourceUpdates(QRhiCommandBuffer *cb, QRhiResourceUpdate
         if (u.type == QRhiResourceUpdateBatchPrivate::BufferOp::DynamicUpdate) {
             QD3D11Buffer *bufD = QRHI_RES(QD3D11Buffer, u.buf);
             Q_ASSERT(bufD->m_type == QRhiBuffer::Dynamic);
-            memcpy(bufD->dynBuf.data() + u.offset, u.data.constData(), size_t(u.dataSize));
+            memcpy(bufD->dynBuf + u.offset, u.data.constData(), size_t(u.dataSize));
             bufD->hasPendingDynamicUpdates = true;
         } else if (u.type == QRhiResourceUpdateBatchPrivate::BufferOp::StaticUpload) {
             QD3D11Buffer *bufD = QRHI_RES(QD3D11Buffer, u.buf);
@@ -1445,7 +1445,7 @@ void QRhiD3D11::enqueueResourceUpdates(QRhiCommandBuffer *cb, QRhiResourceUpdate
             QD3D11Buffer *bufD = QRHI_RES(QD3D11Buffer, u.buf);
             if (bufD->m_type == QRhiBuffer::Dynamic) {
                 u.result->data.resize(u.readSize);
-                memcpy(u.result->data.data(), bufD->dynBuf.constData() + u.offset, size_t(u.readSize));
+                memcpy(u.result->data.data(), bufD->dynBuf + u.offset, size_t(u.readSize));
             } else {
                 BufferReadback readback;
                 readback.result = u.result;
@@ -2155,7 +2155,7 @@ void QRhiD3D11::updateShaderResourceBindings(QD3D11ShaderResourceBindings *srbD,
 
 void QRhiD3D11::executeBufferHostWrites(QD3D11Buffer *bufD)
 {
-    if (!bufD->hasPendingDynamicUpdates)
+    if (!bufD->hasPendingDynamicUpdates || bufD->m_size < 1)
         return;
 
     Q_ASSERT(bufD->m_type == QRhiBuffer::Dynamic);
@@ -2163,7 +2163,7 @@ void QRhiD3D11::executeBufferHostWrites(QD3D11Buffer *bufD)
     D3D11_MAPPED_SUBRESOURCE mp;
     HRESULT hr = context->Map(bufD->buffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mp);
     if (SUCCEEDED(hr)) {
-        memcpy(mp.pData, bufD->dynBuf.constData(), size_t(bufD->dynBuf.size()));
+        memcpy(mp.pData, bufD->dynBuf, size_t(bufD->m_size));
         context->Unmap(bufD->buffer, 0);
     } else {
         qWarning("Failed to map buffer: %s", qPrintable(comErrorMessage(hr)));
@@ -2600,11 +2600,12 @@ void QD3D11Buffer::destroy()
     if (!buffer)
         return;
 
-    dynBuf.clear();
-
     buffer->Release();
     buffer = nullptr;
 
+    delete[] dynBuf;
+    dynBuf = nullptr;
+
     if (uav) {
         uav->Release();
         uav = nullptr;
@@ -2664,7 +2665,7 @@ bool QD3D11Buffer::create()
     }
 
     if (m_type == Dynamic) {
-        dynBuf.resize(m_size);
+        dynBuf = new char[nonZeroSize];
         hasPendingDynamicUpdates = false;
     }
 
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