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826dbcfb2b
Previously, there were a lot of nops after conditional branches. They
come from branch to LIR labels:
./miniruby --zjit-call-threshold=1 --zjit-dump-disasm -e 'Object || String'
# Insn: v14 CheckInterrupts
# RUBY_VM_CHECK_INTS(ec)
ldur w2, [x20, #0x20]
tst w2, w2
b.ne #0x120900278
nop
nop
nop
nop
nop
# Insn: v15 Test v11
tst x0, #-5
mov x2, #0
mov x3, #1
csel x2, x2, x3, eq
# Insn: v16 IfTrue v15, bb3(v6, v11)
tst x2, x2
b.eq #0x120900198
nop
nop
nop
nop
nop
They gunk up the disassembly and can't be helpful for speed. This commit
removes them. I think they were accidentally inherited from certain YJIT
branches that require padding for patching. ZJIT doesn't have these
requirements.
Use a single branch instruction for conditional branches to labels; Jmp
already uses a single `B` instruction. This will work for assemblers
that generate less than ~260,000 instructions -- plenty.
Let the CodeBlock::label_ref() callback return a failure, so we can
fail compilation instead of panicking in case we do get large offsets.