diff options
| author | Alasdair | 2018-11-28 00:29:10 +0000 |
|---|---|---|
| committer | Alasdair | 2018-11-28 00:36:13 +0000 |
| commit | 3a0bcd6e7f1dd565fb41574285c9c09bbbe14697 (patch) | |
| tree | f6fc3f0720eea07fe376c28ebad8d23b86e008c2 /src/constant_fold.ml | |
| parent | 134ceff00b6a4837b133cb49b6d775161420dc62 (diff) | |
Allow folding constant expressions into single register reads
Essentially all we have to do to make this work is introduce a member of
the Value type, V_attempted_read <reg>, which is returned whenever we
try to read a register value with allow_registers disabled. This defers
the failure from reading the register to the point where the register
value is used (simply because nothing knows how to deal with
V_attempted_read). However, if V_attempted_read is returned directly as
the result of evaluating an expression, then we can replace the
expression with a single direct register read. This optimises some
indirection in the ARM specification.
Diffstat (limited to 'src/constant_fold.ml')
| -rw-r--r-- | src/constant_fold.ml | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/src/constant_fold.ml b/src/constant_fold.ml index f22b48de..0e34ed5b 100644 --- a/src/constant_fold.ml +++ b/src/constant_fold.ml @@ -78,6 +78,7 @@ and exp_of_value = | V_tuple vs -> mk_exp (E_tuple (List.map exp_of_value vs)) | V_unit -> mk_lit_exp L_unit + | V_attempted_read str -> mk_exp (E_id (mk_id str)) | _ -> failwith "No expression for value" (* We want to avoid evaluating things like print statements at compile |