high level optimizer

• string-nth 123 eq? -- use string-nth-fast here
• speed up binary-reduce
• compile range iteration better
• fix predicate propagation
• [ 1 2 <cursor> ] [ f ] if dup [ A ] [ B ] if we need better constraints so that A has slots
• loop inversion
• perhaps interval inference is unsound for fixnum+fast etc?
• branch fusion
• growable resize computation may overflow with 3 but not 2 1+
• >fixnum dup { [ 0 >= ] [ 0 <= ] } && [ 1 + ] when -- we don't optimize this

if we change =, we can do this,

[ dup 0.0 eq? [ dup 0 eq? [ ] [ ] if ] [ ] if ] should not optimize
[ dup 0.0 eq? [ dup 0 = [ ] [ ] if ] [ ] if ] should
[ dup 0.0 = [ dup 0 eq? [ ] [ ] if ] [ ] if ] should not optimize
[ dup 0.0 = [ dup 0 = [ ] [ ] if ] [ ] if ] should
[ dup 0.0 = [ 3 * ] when ] should
[ dup 0.0 number= [ 3 * ] when ] should

• peg.javascript.parser take long time to load
• remove-mixin-instance takes a long time
• SPECIAL: foo -- compile versions of foo for different input classes
• [ { fixnum } declare 3 shift >fixnum ] optimized. should optimize down to fixnum-shift-fast
• 2 <sliced-groups> [ ... ] assoc-each -- first2 has a bounds check, kill it

done:

• integer-integer partial ops should use both-fixnums?
• partial dispatch ops should be flushable, and should have input-classes decls
• optimize out both-fixnums? where possible
• inlining heuristic: number of usages within this word
• we want some way to define HINTS: for literal values
• use the specialized-def when inlining?
• above two items are motivated by a desire to specialize <float-array> for small arrays, to speed up raytracer and nbody
• fixnum/i --> fixnum/i-fast if denominator is positive!
• [ <=> ] sort [ <=> ] sort [ <=> ] sort -- still doesn't scale linearly
• don't inline push, unless we have a non-vector, pointless
• remove support for 'f' from intervals
• add identities for integer math

low level optimizer

• DCE: set-slot on a freshly-allocated object should not mark it live
• VN should use identity comparison for ##load-literal instead of value equality
• combine VN with constant branch folding as a first step towards global optimization?
• once low level IR is SSA, we don't have to spill a live interval which has already been spilled once
• tag { ... } dispatch: we can eliminate a shift instruction there
• the tagged comparison optimization is not actually sound
• 2 swap fixnum+fast
• 2 fixnum+fast 1 fixnum+fast

done:

• powerpc: intrinsics for fixnum+, fixnum-, fixnum
• fixnum+ doesn't have an intrinsic anymore
• powerpc: clean up stack-frame code and test spilling
• powerpc: enable float intrinsics
• dispatch: there's a potential jump to a jump here
• linux-ppc: save/restore nonvolatile fp registers
• dispatch branch alignment off
• spilling: align stack on windows (or use unaligned load/store insns?), leave room in stack frame for integer and float spills, resolve pass
• need an optimizer pass to get rid of jumps to returns and jumps to jumps