path: root/src
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authorJonathan Liu <>2016-08-24 11:18:37 +1000
committerJonathan Liu <>2016-08-28 21:06:17 +0000
commitfcc2c95421710f98c7b2dec73e2c8b0d9164bc9b (patch)
tree68bde75b486710445df53fbaee1f3386046ca1a7 /src
parent7179846a0141c2683c30d03c43a7c12fde98801f (diff)
Workaround crashes in QtQml code related to dead-store elimination
When compiled in release mode with GCC 6, QtQml may crash. This is because the C++ compiler is more aggressive about dead-store elimination in situations where a memory store to a location precedes the construction of an object at that memory location. The QV4::MemoryManager::allocate{Managed,Object} functions allocate memory and write to it before the caller does a placement new to construct an object in the same memory. The compiler considers these writes before the constructor as "dead stores" and eliminates them. The -fno-lifetime-dse compiler flag is added to disable this more aggressive dead-store eliminiation optimization. This is a temporary workaround until a proper solution is found. Task-number: QTBUG-55482 Change-Id: I7dbae6e9e613e53ce5fb25957c449bc6657803b5 Reviewed-by: Thiago Macieira <>
Diffstat (limited to 'src')
1 files changed, 1 insertions, 1 deletions
diff --git a/src/qml/ b/src/qml/
index f4862a17a6..651afa6b75 100644
--- a/src/qml/
+++ b/src/qml/
@@ -18,7 +18,7 @@ exists("qqml_enable_gcov") {
greaterThan(QT_GCC_MAJOR_VERSION, 5) {
# Our code is bad. Temporary workaround.
- QMAKE_CXXFLAGS += -fno-delete-null-pointer-checks
+ QMAKE_CXXFLAGS += -fno-delete-null-pointer-checks -fno-lifetime-dse
QMAKE_DOCS = $$PWD/doc/qtqml.qdocconf