Written entirely by Claude (Anthropic's Claude Code), at the request of
and under the direction of dgryski, on the dgryski/llvm23 branch (LLVM
22 support, in preparation for the eventual LLVM 23 release; the
corresponding go-llvm branch of the same name adds the matching
binding support this depends on).
Found while running real-world Go test suites through a tinygo built
against LLVM 22 (as a smoke test of the earlier captures(none)/
nocapture and lifetime-intrinsic fixes on this branch): `tinygo test`
on github.com/dgryski/go-rc5 panicked at compile time with "unknown
value" inside interp.(*runner).getValue, while compiling
(*sync.Once).Do. Bisecting against LLVM 21 (unaffected) narrowed it to
a change introduced in LLVM 22 specifically, unrelated to the earlier
captures/lifetime work.
Root cause: LLVM 22 stopped exposing switch-instruction case values as
regular instruction operands -- only the condition and
destination-block operands remain. interp/compiler.go's `case
llvm.Switch:` handling walked raw operands assuming the old
alternating (value, label) layout, so under LLVM 22 it read a
destination *block* where it expected an integer case value,
eventually panicking deep inside a getValue call it couldn't resolve.
This only manifested on functions actually compiled by the interp
package (TinyGo's compile-time evaluator for global initializers) that
happen to reach a switch-based dispatch, such as sync.Once's
defer-based Do method -- hence it needed a real, moderately complex
package (crypto/cipher via go-rc5) to surface, and never showed up in
smaller smoke tests.
Fix: use the new version-independent Value.SuccessorsCount()/
Value.Successor(i) and Value.GetSwitchCaseValue(i) helpers just added
to go-llvm, instead of raw Operand() indexing.
Also applies the same captures(none)/nocapture golden-IR normalization
already used in transform/transform_test.go and compiler/compiler_test.go
to interp/interp_test.go's separate copy of the same comparator helper,
which was missed in the earlier pass and started failing two of its
subtests once actually run against LLVM 22.
Verified: `tinygo test` on go-rc5 now passes reliably (repeated runs)
against both LLVM 20 (default) and LLVM 22; full transform/compiler/
interp/cgo/goenv test suites pass on both versions. The `builder`
package has pre-existing, environment-related test failures (stale
GOROOT cache, local clang/target-feature drift) confirmed identical
against an unmodified LLVM 20 build, so unrelated to this change.
I've discovered a bug in the implementation of the PHI instruction in
the interp package. This commit fixes the bug.
I've found this issue while investigating an issue with maps after
running interp per package.
A switch statement is not normally emitted by the compiler package, but
LLVM function passes may convert a series of if/else pairs to a switch
statement. A future change will run function passes in the package
compile phase, so the interp package (which is also run after all
modules are merged together) will need to deal with these new switch
statements.
For a full explanation, see interp/README.md. In short, this rewrite is
a redesign of the partial evaluator which improves it over the previous
partial evaluator. The main functional difference is that when
interpreting a function, the interpretation can be rolled back when an
unsupported instruction is encountered (for example, an actual unknown
instruction or a branch on a value that's only known at runtime). This
also means that it is no longer necessary to scan functions to see
whether they can be interpreted: instead, this package now just tries to
interpret it and reverts when it can't go further.
This new design has several benefits:
* Most errors coming from the interp package are avoided, as it can
simply skip the code it can't handle. This has long been an issue.
* The memory model has been improved, which means some packages now
pass all tests that previously didn't pass them.
* Because of a better design, it is in fact a bit faster than the
previous version.
This means the following packages now pass tests with `tinygo test`:
* hash/adler32: previously it would hang in an infinite loop
* math/cmplx: previously it resulted in errors
This also means that the math/big package can be imported. It would
previously fail with a "interp: branch on a non-constant" error.
Damian Gryski
Jake Bailey
Kenneth Bell
shivay
Ayke van Laethem