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Stephan Renatus
81a774a60d
* wasm: optimize package access with non-ground refs using call_indrect
We now
1. write an object corresponding to data paths into the module data
2. initialize an opa_object_t from that using `_initialize`, called
as the module's Start function
3. write out CallDynamicStmts in IR when the ref is not all ground,
but its vars have been seen
4. compile those CallDynamicStmts to call_indirect invocations in
WASM, preceded by a lookup using the path in the object prepared
in (2.)
5. if the lookup fails to come up with a result, the eval goes
undefined
What it looks like:
With t.rego as
package t
p {
data.foo[input.x].bar.p
}
and foo.rego as
package foo.a.bar
p = true
when building policy.wasm using `opa build -t wasm -e t/p t.rego foo.rego`,
the body of function `g0.data.t.p` will contain
i32.const 5
call $opa_array_with_cap
local.set $11
local.get $11
local.get $7
call $opa_array_append
local.get $11
local.get $8
call $opa_array_append
local.get $11
local.get $6
call $opa_array_append
local.get $11
local.get $9
call $opa_array_append
local.get $11
local.get $10
call $opa_array_append
local.get $0
local.get $1
local.get $11
call $opa_mapping_lookup
local.tee $12
i32.eqz
br_if $block
local.get $12
call_indirect $29 (type $1)
local.tee $13
i32.eqz
br_if $block
Where the array-related functions build an array of
["g0", "foo", input.x, "bar", "p"]
and pass that to `opa_mapping_lookup` to determine the element index to
pass to `call_indirect`. The lookup function returns 74 from the JSON
blob put into the data section,
(data $38 (i32.const 56485)
"{\"g0\": {\"foo\": {\"a\": {\"bar\": {\"p\": 74}}}, \"t\": {\"p\": 75}}}")
iff input.x happens to be "a". Otherwise, it'll return 0, and the result
will end up being undefined.
Element 74 of the modules func table is, of course, $g0.data.foo.a.bar.p:
(elem $33 (i32.const 74)
$g0.data.foo.a.bar.p $g0.data.t.p)
($33 is some id of that piece of function table, an artifact of the
`wavm disassemble` output.)
* compiler/wasm: add memoization to call_indirect logic
- adds a data segment for mapping element indices (used with call_indirect)
to function indices (as used with opa_memoize_{get,insert})
- emits mapping function elem -> func idx that uses that data segment
- wires up memoization lookup and insert in call_indirect code path
The added test case would cause `make wasm-rego-test` to fail like this
if memoization wasn't happening:
ERROR 019_call_indirect_optimization.json: memoization: should have been memoized
* planner: add debug messages, carry them over into the compiler
Signed-off-by: Stephan Renatus <stephan.renatus@gmail.com>