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Diffstat (limited to 'src/cmd/compile/internal/ssa/TODO')
| -rw-r--r-- | src/cmd/compile/internal/ssa/TODO | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/TODO b/src/cmd/compile/internal/ssa/TODO new file mode 100644 index 0000000000..a457e67101 --- /dev/null +++ b/src/cmd/compile/internal/ssa/TODO @@ -0,0 +1,68 @@ +This is a list of things that need to be worked on. It will hopefully +be complete soon. + +Coverage +-------- + +Correctness +----------- +- Debugging info (check & fix as much as we can) + +Optimizations (better compiled code) +------------------------------------ +- Reduce register pressure in scheduler +- More strength reduction: multiply -> shift/add combos (Worth doing?) +- Add a value range propagation pass (for bounds elim & bitwidth reduction) +- Make dead store pass inter-block +- redundant CMP in sequences like this: + SUBQ $8, AX + CMP AX, $0 + JEQ ... +- If there are a lot of MOVQ $0, ..., then load + 0 into a register and use the register as the source instead. +- Allow arrays of length 1 (or longer, with all constant indexes?) to be SSAable. +- Figure out how to make PARAMOUT variables ssa-able. + They need to get spilled automatically at end-of-function somehow. +- If strings are being passed around without being interpreted (ptr + and len fields being accessed) pass them in xmm registers? + Same for interfaces? +- OpArrayIndex should take its index in AuxInt, not a full value. +- remove FLAGS from REP instruction clobbers +- (x86) Combine loads into other ops + Note that this is challenging for ops that generate flags + because flagalloc wants to move those instructions around for + flag regeneration. +- Non-constant rotate detection. +- Do 0 <= x && x < n with one unsigned compare +- nil-check removal in indexed load/store case: + lea (%rdx,%rax,1),%rcx + test %al,(%rcx) // nil check + mov (%rdx,%rax,1),%cl // load to same address +- any pointer generated by unsafe arithmetic must be non-nil? + (Of course that may not be true in general, but it is for all uses + in the runtime, and we can play games with unsafe.) + +Optimizations (better compiler) +------------------------------- +- Smaller Value.Type (int32 or ptr)? Get rid of types altogether? +- OpStore uses 3 args. Increase the size of Value.argstorage to 3? +- Use a constant cache for OpConstNil, OpConstInterface, OpConstSlice, maybe OpConstString +- Handle signed division overflow and sign extension earlier +- Implement 64 bit const division with high multiply, maybe in the frontend? +- Add bit widths to complex ops + +Regalloc +-------- +- Make less arch-dependent +- Allow return values to be ssa-able +- Handle 2-address instructions +- Make liveness analysis non-quadratic + +Future/other +------------ +- Start another architecture (arm?) +- 64-bit ops on 32-bit machines +- Investigate type equality. During SSA generation, should we use n.Type or (say) TypeBool? +- Should we get rid of named types in favor of underlying types during SSA generation? +- Should we introduce a new type equality routine that is less strict than the frontend's? +- Infrastructure for enabling/disabling/configuring passes |