[EH] Fuzz throws from JS (#7027)

We already generated (throw ..) instructions in wasm, but it makes sense to model
throws from outside as well, as they cross the module boundary. This adds a new fuzzer
import to the generated modules, "throw", that just does a throw from JS etc.

Also be more precise about handling fuzzing-support imports in fuzz-exec: we now
check that logging functions start with "log*" and error otherwise (this check is
now needed given we have "throw", which is not logging). Also fix a minor issue
with name conflicts for logging functions by using getValidFunctionName for them,
both for logging and for throw.

1 files changed, 39 insertions, 0 deletions

diff --git a/test/lit/exec/fuzzing-api.wast b/test/lit/exec/fuzzing-api.wast
new file mode 100644
index 000000000..d37d7ef4a
--- /dev/null
+++ b/test/lit/exec/fuzzing-api.wast
@@ -0,0 +1,39 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py --output=fuzz-exec and should not be edited.
+
+;; RUN: wasm-opt %s -all --fuzz-exec -o /dev/null 2>&1 | filecheck %s
+
+;; Test the fuzzing-support module imports.
+
+(module
+ (import "fuzzing-support" "log-i32" (func $log-i32 (param i32)))
+ (import "fuzzing-support" "log-f64" (func $log-f64 (param f64)))
+
+ (import "fuzzing-support" "throw" (func $throw))
+
+ ;; CHECK:      [fuzz-exec] calling logging
+ ;; CHECK-NEXT: [LoggingExternalInterface logging 42]
+ ;; CHECK-NEXT: [LoggingExternalInterface logging 3.14159]
+ (func $logging (export "logging")
+  (call $log-i32
+   (i32.const 42)
+  )
+  (call $log-f64
+   (f64.const 3.14159)
+  )
+ )
+
+ ;; CHECK:      [fuzz-exec] calling throwing
+ ;; CHECK-NEXT: [exception thrown: __private ()]
+ ;; CHECK-NEXT: warning: no passes specified, not doing any work
+ (func $throwing (export "throwing")
+  (call $throw)
+ )
+)
+;; CHECK:      [fuzz-exec] calling logging
+;; CHECK-NEXT: [LoggingExternalInterface logging 42]
+;; CHECK-NEXT: [LoggingExternalInterface logging 3.14159]
+
+;; CHECK:      [fuzz-exec] calling throwing
+;; CHECK-NEXT: [exception thrown: __private ()]
+;; CHECK-NEXT: [fuzz-exec] comparing logging
+;; CHECK-NEXT: [fuzz-exec] comparing throwing