FTL B3 should do tail calls
https://bugs.webkit.org/show_bug.cgi?id=152494
Reviewed by Michael Saboff.
OMG this was so easy.
The only shady part is that I broke a layering rule that we had so far been following: B3 was
sitting below the JSC runtime, and did not use JS-specific types. No more, since B3::ValueRep
can now turn itself into a ValueRecovery for a JSValue. This small feature makes a huge
difference for the readability of tail call code: it makes it plain that the call frame
shuffler is basically just directly consuming the stackmap generation params, and insofar as
there is any data transformation, it's just because it uses different classes to say the same
thing.
I think we should avoid adding too many JS-specific things to B3. But, so long as it's still
possible to use B3 to compile things that aren't JS, I think we'll be fine.
* b3/B3ValueRep.cpp:
(JSC::B3::ValueRep::dump):
(JSC::B3::ValueRep::emitRestore):
(JSC::B3::ValueRep::recoveryForJSValue):
* b3/B3ValueRep.h:
* ftl/FTLLowerDFGToLLVM.cpp:
(JSC::FTL::DFG::LowerDFGToLLVM::compileTailCall):
(JSC::FTL::DFG::LowerDFGToLLVM::compileCallOrConstructVarargs):
* test/stress/ftl-tail-call.js: Added.
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@194368 268f45cc-cd09-0410-ab3c-d52691b4dbfc
5 files changed
