FTL should be able to run everything in Octane/regexp

FTL should be able to run everything in Octane/regexp
https://bugs.webkit.org/show_bug.cgi?id=154266

Reviewed by Saam Barati.

Adds FTL support for NewRegexp, RegExpTest, and RegExpExec. I couldn't figure out how to
make the RegExpExec peephole optimization work in FTL. This optimizations shouldn't be a
DFG backend optimization anyway - if we need this optimization then it should be a
strength reduction rule over IR. That way, it can be shared by all backends.

I measured whether removing that optimization had any effect on performance separately
from measuring the performance of this patch. Removing that optimization did not change
our score on any benchmarks.

This patch does have an overall negative effect on the Octane/regexp score. This is
presumably because tiering up to the FTL has no value to the code in the regexp test. Or
maybe it's something else. No matter - the overall effect on the Octane score is not
statistically significant and we don't want this kind of coverage blocked by the fact
that adding coverage hurts a benchmark.

* dfg/DFGByteCodeParser.cpp:
(JSC::DFG::ByteCodeParser::parseBlock):
* dfg/DFGNode.h:
(JSC::DFG::Node::setIndexingType):
(JSC::DFG::Node::hasRegexpIndex):
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compileNotifyWrite):
(JSC::DFG::SpeculativeJIT::compileIsObjectOrNull):
(JSC::DFG::SpeculativeJIT::compileRegExpExec): Deleted.
* dfg/DFGSpeculativeJIT32_64.cpp:
(JSC::DFG::SpeculativeJIT::compile):
* dfg/DFGSpeculativeJIT64.cpp:
(JSC::DFG::SpeculativeJIT::compile):
* ftl/FTLCapabilities.cpp:
(JSC::FTL::canCompile):
* ftl/FTLLowerDFGToB3.cpp:
(JSC::FTL::DFG::LowerDFGToB3::compileNode):
(JSC::FTL::DFG::LowerDFGToB3::compileCheckWatchdogTimer):
(JSC::FTL::DFG::LowerDFGToB3::compileRegExpExec):
(JSC::FTL::DFG::LowerDFGToB3::compileRegExpTest):
(JSC::FTL::DFG::LowerDFGToB3::compileNewRegexp):
(JSC::FTL::DFG::LowerDFGToB3::didOverflowStack):
* tests/stress/ftl-regexp-exec.js: Added.
* tests/stress/ftl-regexp-test.js: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@197357 268f45cc-cd09-0410-ab3c-d52691b4dbfc