From 2b758fbdc46fc8fe5241bcf1ba5bbd81e6d556ed Mon Sep 17 00:00:00 2001
From: Heejin Ahn <aheejin@gmail.com>
Date: Fri, 27 Mar 2020 21:51:40 -0700
Subject: Error out when EH is used in unsupported code (#2713)

This calls `Fatal()` when EH instructions are used in unsupported code.
Currently EH instructions are unsupported in Flatten, ReReloop, and
DataFlow-using passes.
---
 src/dataflow/graph.h    | 3 +++
 src/passes/Flatten.cpp  | 5 +++++
 src/passes/ReReloop.cpp | 3 +++
 3 files changed, 11 insertions(+)

(limited to 'src')

diff --git a/src/dataflow/graph.h b/src/dataflow/graph.h
index 6a984ad72..114a38f11 100644
--- a/src/dataflow/graph.h
+++ b/src/dataflow/graph.h
@@ -230,6 +230,9 @@ struct Graph : public UnifiedExpressionVisitor<Graph, Node*> {
       return doVisitUnreachable(unreachable);
     } else if (auto* drop = curr->dynCast<Drop>()) {
       return doVisitDrop(drop);
+    } else if (curr->is<Try>() || curr->is<Throw>() || curr->is<Rethrow>() ||
+               curr->is<BrOnExn>()) {
+      Fatal() << "DataFlow does not support EH instructions yet";
     } else {
       return doVisitGeneric(curr);
     }
diff --git a/src/passes/Flatten.cpp b/src/passes/Flatten.cpp
index 0a6a7022a..9139d5dca 100644
--- a/src/passes/Flatten.cpp
+++ b/src/passes/Flatten.cpp
@@ -68,6 +68,11 @@ struct Flatten
       return;
     }
 
+    if (curr->is<Try>() || curr->is<Throw>() || curr->is<Rethrow>() ||
+        curr->is<BrOnExn>()) {
+      Fatal() << "Flatten does not support EH instructions yet";
+    }
+
     if (Properties::isControlFlowStructure(curr)) {
       // handle control flow explicitly. our children do not have control flow,
       // but they do have preludes which we need to set up in the right place
diff --git a/src/passes/ReReloop.cpp b/src/passes/ReReloop.cpp
index 8f83f8a8f..004e922ed 100644
--- a/src/passes/ReReloop.cpp
+++ b/src/passes/ReReloop.cpp
@@ -284,6 +284,9 @@ struct ReReloop final : public Pass {
       ReturnTask::handle(*this, ret);
     } else if (auto* un = curr->dynCast<Unreachable>()) {
       UnreachableTask::handle(*this, un);
+    } else if (curr->is<Try>() || curr->is<Throw>() || curr->is<Rethrow>() ||
+               curr->is<BrOnExn>()) {
+      Fatal() << "ReReloop does not support EH instructions yet";
     } else {
       // not control flow, so just a simple element
       getCurrBlock()->list.push_back(curr);
-- 
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