tree d10a64a9ad0cd6a58d86364f1c72dc47902c95df
parent 06aab28ba4033eb4b1e6cfdc4a754a57f966323b
author sbarati@apple.com <sbarati@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1579317871 +0000
committer sbarati@apple.com <sbarati@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1579317871 +0000

Air O0 should have better stack allocation
https://bugs.webkit.org/show_bug.cgi?id=206436

Reviewed by Tadeu Zagallo.

JSTests:

* wasm/stress/dont-stack-overflow-in-air.js: Added.

Source/JavaScriptCore:

This patch adds a simple stack slot allocator to Air O0 to make code
use smaller stack frames. The huge stack frames from the old stack
allocator were leading to stack overflows in some programs. Before,
each Tmp got its own stack slot. The new allocator works similar to O0's
register allocator. This stack allocator linearizes the program and uses live
range end as an opportunity to place the stack slot on a free list of
available stack slots. This patch also fixes an issue in our linearization code
where the head of a block and the tail of another block would share the
same linearization index. This didn't matter for register allocation, but
does matter for the stack allocator. So "live at head", and "live at tail"
now get their own linearization index.

* b3/air/AirAllocateRegistersAndStackAndGenerateCode.cpp:
(JSC::B3::Air::GenerateAndAllocateRegisters::buildLiveRanges):
(JSC::B3::Air::GenerateAndAllocateRegisters::prepareForGeneration):
(JSC::B3::Air::GenerateAndAllocateRegisters::generate):
* b3/air/AirAllocateRegistersAndStackAndGenerateCode.h:
* b3/air/AirLiveness.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@254788 268f45cc-cd09-0410-ab3c-d52691b4dbfc