Limit literal printing to a reasonable limit (#5779)

Without this, a massive GC array for example can end up being printed as a huge
amount of output, which is a problem in the fuzzer. I noticed this because a testcase
was taking minutes to run.

Perhaps we should add an option (BINARYEN_PRINT_FULL=1?) to disable this limit,
but let's see if we ever need that.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/wasm/literal.cpp b/src/wasm/literal.cpp
index 53740c773..a0e3d2bf6 100644
--- a/src/wasm/literal.cpp
+++ b/src/wasm/literal.cpp
@@ -626,6 +626,10 @@ std::ostream& operator<<(std::ostream& o, Literal literal) {
   return o;
 }
 
+// Printing literals is mainly for debugging purposes, and they can be of
+// massive size, so abbreviate past some point.
+static size_t LITERALS_PRINT_LIMIT = 20;
+
 std::ostream& operator<<(std::ostream& o, wasm::Literals literals) {
   if (literals.size() == 1) {
     return o << literals[0];
@@ -636,6 +640,10 @@ std::ostream& operator<<(std::ostream& o, wasm::Literals literals) {
     }
     for (size_t i = 1; i < literals.size(); ++i) {
       o << ", " << literals[i];
+      if (i == LITERALS_PRINT_LIMIT) {
+        o << "[..]";
+        break;
+      }
     }
     return o << ')';
   }