tree a02a20180b0614a4055feeb1c9d6cf052da05641
parent 9ef22d7bc7f38eeb96603cd9326af63bb1e3da6b
author jfbastien@apple.com <jfbastien@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1524886344 +0000
committer jfbastien@apple.com <jfbastien@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1524886344 +0000

Make the first 64 bits of JSString look like a double JSValue
https://bugs.webkit.org/show_bug.cgi?id=185081

Reviewed by Filip Pizlo.

We can be clever about how we lay out JSString so that, were it
reinterpreted as a JSValue, it would look like a double.

* assembler/MacroAssemblerX86Common.h:
(JSC::MacroAssemblerX86Common::and16):
* assembler/X86Assembler.h:
(JSC::X86Assembler::andw_mr):
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compileMakeRope):
* ftl/FTLLowerDFGToB3.cpp:
(JSC::FTL::DFG::LowerDFGToB3::compileMakeRope):
* ftl/FTLOutput.h:
(JSC::FTL::Output::store32As8):
(JSC::FTL::Output::store32As16):
* runtime/JSString.h:
(JSC::JSString::JSString):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@231129 268f45cc-cd09-0410-ab3c-d52691b4dbfc