I'm fixing a bug which involves initialization of a field of an object in its placement new function before the constructor is called. This is falling foul of DSE, which deletes the field initialization.
I see this: @item -fno-lifetime-dse @opindex fno-lifetime-dse In C++ the value of an object is only affected by changes within its lifetime: when the constructor begins, the object has an indeterminate value, and any changes during the lifetime of the object are dead when the object is destroyed. Normally dead store elimination will take advantage of this; if your code relies on the value of the object storage persisting beyond the lifetime of the object, you can use this flag to disable this optimization. I'm quite happy to believe this, and treat my bug simply as an error between chair and keyboard, but I cannot find the language in the C++ standard which declares that the lifetime of an object begins with its constructor, and thus any stores into the object performed by placement new may be deleted. Can someone please tell me Chapter and Verse in the standard, please? Then I can close this one. Thanks, Andrew.
