From 2aa0cf300998c62aea8cc6698f8325653a9f0895 Mon Sep 17 00:00:00 2001
From: Thomas Lively <7121787+tlively@users.noreply.github.com>
Date: Wed, 9 Sep 2020 13:01:21 -0700
Subject: Poppy IR wast parsing and validation (#3105)

Adds an IR profile to each function so the validator can determine
which validation rules to apply and adds a flag to have the wast
parser set the profile to Poppy for testing purposes.
---
 src/ir/stack-utils.h | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

(limited to 'src/ir/stack-utils.h')

diff --git a/src/ir/stack-utils.h b/src/ir/stack-utils.h
index 89ec7d47e..fc23b6080 100644
--- a/src/ir/stack-utils.h
+++ b/src/ir/stack-utils.h
@@ -33,7 +33,10 @@
 //     stack type of each instruction. Pops may not have `unreachable` type.
 //
 //  4. Only control flow structures and instructions that have polymorphic
-//     unreachable behavior in WebAssembly may have unreachable type.
+//     unreachable behavior in WebAssembly may have unreachable type. Blocks may
+//     be unreachable when they are not branch targets and when they have an
+//     unreachable child. Note that this means a block may be unreachable even
+//     if it would otherwise have a concrete type, unlike in Binaryen IR.
 //
 // For example, the following Binaryen IR Function:
 //
@@ -58,7 +61,10 @@
 //   )
 //
 // Notice that the sequence of instructions in the block is now identical to the
-// sequence of instructions in raw WebAssembly.
+// sequence of instructions in raw WebAssembly. Also note that Poppy IR's
+// validation rules are largely additional on top of the normal Binaryen IR
+// validation rules, with the only exceptions being block body validation and
+// block unreahchability rules.
 //
 
 #ifndef wasm_ir_stack_h
@@ -75,6 +81,10 @@ namespace StackUtils {
 // Iterate through `block` and remove nops.
 void removeNops(Block* block);
 
+// Whether `expr` may be unreachable in Poppy IR. True for control flow
+// structures and polymorphic unreachable instructions.
+bool mayBeUnreachable(Expression* expr);
+
 } // namespace StackUtils
 
 // Stack signatures are like regular function signatures, but they are used to
-- 
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