From 114ed43b24d3c74112b922a7469c48c736172833 Mon Sep 17 00:00:00 2001 From: Alon Zakai Date: Tue, 1 Aug 2017 10:22:31 -0700 Subject: fix proper wasm emitting of untaken br_tables --- src/wasm/wasm-binary.cpp | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'src/wasm/wasm-binary.cpp') diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp index 88b967fdf..47bcc8ba5 100644 --- a/src/wasm/wasm-binary.cpp +++ b/src/wasm/wasm-binary.cpp @@ -666,6 +666,14 @@ void WasmBinaryWriter::visitSwitch(Switch *curr) { recurse(curr->value); } recurse(curr->condition); + if (!BranchUtils::isBranchTaken(curr)) { + // if the branch is not taken, then it's dangerous to emit it, as + // wasm type checking rules are stricter than ours - we tolerate + // an untaken branch to a target with a different value, but not + // wasm. so just don't emit it + o << int8_t(BinaryConsts::Unreachable); + return; + } o << int8_t(BinaryConsts::TableSwitch) << U32LEB(curr->targets.size()); for (auto target : curr->targets) { o << U32LEB(getBreakIndex(target)); @@ -1796,7 +1804,7 @@ void WasmBinaryBuilder::processExpressions() { // until an end or else marker, o Expression* WasmBinaryBuilder::popExpression() { if (expressionStack.empty()) { - throw ParseException("attempted pop from empty stack"); + throw ParseException("attempted pop from empty stack at " + std::to_string(pos)); } auto ret = expressionStack.back(); // to simulate the wasm polymorphic stack mode, leave a final -- cgit v1.2.3