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Jake Bailey
18033ebc36
* compiler, runtime, reflect: generate type-specific hash/equal for composite map keys
For map keys that are not trivially binary-comparable, the compiler now
generates type-specific hash and equal functions as LLVM IR instead of
going through the interface+reflection path. This covers comparable
types: strings, floats, complex numbers, interfaces, channels, and
composites containing any mix of these.
Previously, maps with composite keys containing strings or floats
converted the key to interface{}, hashed via reflection, and compared
through interface equality. Now the compiler walks struct fields and
array elements directly, dispatching to the right runtime helper for
each field type and storing keys at their actual type.
Struct keys are always handled field-by-field so padding bytes do not
affect equality or hashing. Blank fields are ignored, matching Go
equality. Generated hash/equal function names use canonical underlying
type structure so structurally identical key types can share generated
functions. Padding zeroing before map operations is no longer needed
because structs no longer use the binary key path.
Also fix reflect map iteration for interface-keyed maps: MapIter.Key
returns an interface Value for map[interface{}] keys instead of
unpacking to the concrete key kind.
* compiler: generate loops for array map key hash/equal
Previously, array key hash and equal functions were unrolled at compile
time, generating one block of IR per element. For large arrays like
[1000]int inside a struct with non-binary fields, this caused code
explosion.
Now, binary-element arrays dispatch directly to hash32/memequal for the
whole array. Non-binary-element arrays generate an LLVM IR loop. The
equal loop short-circuits on the first mismatch.
Small arrays are still unrolled instead of looping, keeping the simple
cases compact.
* reflect: fix at-runtime map issues from review, and more found locally
Maps created through reflect.MakeMap need hash/equal behavior that
matches compiler-created maps. Add hashmapMakeReflect for composite key
types, using runtime closures that reconstruct interface{} values from
raw key bytes and delegate to the interface hash and equality paths.
Interface-keyed maps are already stored as interface values, so use the
existing interface hash/equal helpers directly for those. This keeps
reflect insert, lookup, delete, and compiled lookup paths consistent.
Also fix addressable small values used as interface map keys or
interface map values. loadSmallValue puts small indirect values back in
the pointer-sized interface data field the same way valueInterfaceUnsafe
does.
* compiler, interp, reflect: fix pointer map literals; remove interface fallback
Package-level map literals with pointer keys (both *T and
unsafe.Pointer) crash the compiler: the interp pass panics when trying
to hash pointer data as raw bytes, because pointer values in the interp
memory model are symbolic identities that do not fit in a byte.
Fix this by setting a recoverable error flag instead of panicking. The
interp detects the error after each instruction and defers the map
insert to runtime init code, where real addresses are available for
hashing. This matches how the interp already handles other operations
it cannot evaluate at compile time.
With this fix, unsafe.Pointer can also be classified as a binary map
key, which was the last type requiring the interface-based fallback.
Since all comparable types now use either the binary or the
compiler-generated hash/equal path, remove the interface fallback from
the compiler and reflect packages.
* compiler, transform: always pass hash/equal function pointers to hashmapMakeGeneric
The compiler now always resolves the hash and equal functions at compile
time and passes them directly to hashmapMakeGeneric, instead of passing
an algorithm enum to hashmapMake and resolving at runtime. For string
keys, the runtime hashmapStringPtrHash/hashmapStringEqual functions are
referenced directly. For binary keys, hash32/memequal are referenced.
The old hashmapMake with alg enum is retained for reflect, which still
needs runtime resolution when creating maps dynamically.
The OptimizeMaps transform pass is updated to handle both hashmapMake
and hashmapMakeGeneric, and to recognize hashmapGenericSet in addition
to hashmapBinarySet and hashmapStringSet. The now-unused
hashmapCanGenerateHashEqual helper is removed.
* runtime: store large map keys and values indirectly
When a map key or value exceeds 128 bytes, the bucket now stores a
pointer to separately allocated memory instead of the data inline. This
matches Go's MapMaxKeyBytes/MapMaxElemBytes threshold and prevents
bucket sizes from exploding for large key/value types.
For example, map[[256]byte]int previously used 2128 bytes per bucket
(16 header + 256*8 keys + 8*8 values); now it uses 144 bytes per bucket
(16 header + 8*8 pointers + 8*8 values).
The indirection is fully encapsulated in the runtime via helper
functions. Store the computed key and value slot sizes on the hashmap so
all runtime and reflect paths use the same bucket layout, including
non-indirect keys and values.
Add big-key golden coverage and benchmarks. Make the benchmark vary
enough key bytes to exercise hashing.
54 lines
1.4 KiB
Go
54 lines
1.4 KiB
Go
package transform
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import (
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"tinygo.org/x/go-llvm"
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)
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// OptimizeMaps eliminates created but unused maps.
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//
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// In the future, this should statically allocate created but never modified
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// maps. This has not yet been implemented, however.
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func OptimizeMaps(mod llvm.Module) {
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hashmapMake := mod.NamedFunction("runtime.hashmapMake")
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hashmapMakeGeneric := mod.NamedFunction("runtime.hashmapMakeGeneric")
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hashmapBinarySet := mod.NamedFunction("runtime.hashmapBinarySet")
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hashmapStringSet := mod.NamedFunction("runtime.hashmapStringSet")
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hashmapGenericSet := mod.NamedFunction("runtime.hashmapGenericSet")
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optimizeMapMake := func(makeFunc llvm.Value) {
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if makeFunc.IsNil() {
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return
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}
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for _, makeInst := range getUses(makeFunc) {
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updateInsts := []llvm.Value{}
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unknownUses := false
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for _, use := range getUses(makeInst) {
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if use := use.IsACallInst(); !use.IsNil() {
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switch use.CalledValue() {
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case hashmapBinarySet, hashmapStringSet, hashmapGenericSet:
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updateInsts = append(updateInsts, use)
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default:
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unknownUses = true
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}
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} else {
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unknownUses = true
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}
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}
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if !unknownUses {
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// This map can be entirely removed, as it is only created
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// but never used.
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for _, inst := range updateInsts {
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inst.EraseFromParentAsInstruction()
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}
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makeInst.EraseFromParentAsInstruction()
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}
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}
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}
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optimizeMapMake(hashmapMake)
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optimizeMapMake(hashmapMakeGeneric)
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}
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