wasm2js: handle unreachable select and global.set

src/passes/I64ToI32Lowering.cpp

@@ -28,6 +28,7 @@
 #include "support/name.h"
 #include "wasm-builder.h"
 #include "ir/flat.h"
+#include "ir/iteration.h"
 #include "ir/memory-utils.h"
 #include "ir/module-utils.h"
 #include "ir/names.h"
@@ -464,6 +465,7 @@ struct I64ToI32Lowering : public WalkerPass<PostWalker<I64ToI32Lowering>> {
   }
 
   void visitSetGlobal(SetGlobal* curr) {
+    if (handleUnreachable(curr)) return;
     if (!originallyI64Globals.count(curr->name)) return;
     TempVar highBits = fetchOutParam(curr->value);
     auto* setHigh = builder->makeSetGlobal(
@@ -1578,6 +1580,7 @@ struct I64ToI32Lowering : public WalkerPass<PostWalker<I64ToI32Lowering>> {
   }
 
   void visitSelect(Select* curr) {
+    if (handleUnreachable(curr)) return;
     if (!hasOutParam(curr->ifTrue)) {
       assert(!hasOutParam(curr->ifFalse));
       return;
@@ -1669,6 +1672,24 @@ struct I64ToI32Lowering : public WalkerPass<PostWalker<I64ToI32Lowering>> {
     highBitVars.erase(e);
     return ret;
   }
+
+  // If e.g. a select is unreachable, then one arm may have an out param
+  // but not the other. In this case dce should really have been run
+  // before; handle it in a simple way here.
+  bool handleUnreachable(Expression* curr) {
+    if (curr->type != unreachable) return false;
+    std::vector<Expression*> children;
+    for (auto* child : ChildIterator(curr)) {
+      if (isConcreteType(child->type)) {
+        child = builder->makeDrop(child);
+      }
+      children.push_back(child);
+    }
+    auto* block = builder->makeBlock(children);
+    assert(block->type == unreachable);
+    replaceCurrent(block);
+    return true;
+  }
 };
 
 Pass *createI64ToI32LoweringPass() {

test/passes/flatten_i64-to-i32-lowering.txt

@@ -78,6 +78,69 @@
    )
   )
  )
+ (func $unreachable-select-i64 (; 2 ;) (type $FUNCSIG$j) (result i32)
+  (local $i64toi32_i32$0 i32)
+  (unreachable)
+  (block
+   (drop
+    (block (result i32)
+     (local.set $i64toi32_i32$0
+      (i32.const 0)
+     )
+     (i32.const 1)
+    )
+   )
+   (unreachable)
+   (drop
+    (i32.const 2)
+   )
+  )
+  (unreachable)
+ )
+ (func $unreachable-select-i64-b (; 3 ;) (type $FUNCSIG$j) (result i32)
+  (local $i64toi32_i32$0 i32)
+  (unreachable)
+  (block
+   (unreachable)
+   (drop
+    (block (result i32)
+     (local.set $i64toi32_i32$0
+      (i32.const 0)
+     )
+     (i32.const 3)
+    )
+   )
+   (drop
+    (i32.const 4)
+   )
+  )
+  (unreachable)
+ )
+ (func $unreachable-select-i64-c (; 4 ;) (type $FUNCSIG$j) (result i32)
+  (local $i64toi32_i32$0 i32)
+  (local $i64toi32_i32$1 i32)
+  (unreachable)
+  (block
+   (drop
+    (block (result i32)
+     (local.set $i64toi32_i32$0
+      (i32.const 0)
+     )
+     (i32.const 5)
+    )
+   )
+   (drop
+    (block (result i32)
+     (local.set $i64toi32_i32$1
+      (i32.const 0)
+     )
+     (i32.const 6)
+    )
+   )
+   (unreachable)
+  )
+  (unreachable)
+ )
 )
 (module
  (type $0 (func (param i32 i32)))
@@ -88,6 +151,7 @@
  (global $g$hi (mut i32) (global.get $f$hi))
  (global $i64toi32_i32$HIGH_BITS (mut i32) (i32.const 0))
  (export "exp" (func $1))
+ (export "unreach" (func $2))
  (func $call (; 0 ;) (type $0) (param $0 i32) (param $0$hi i32)
   (nop)
  )
@@ -136,4 +200,42 @@
   )
   (nop)
  )
+ (func $2 (; 2 ;) (type $1)
+  (local $0 i32)
+  (local $0$hi i32)
+  (local $1 i32)
+  (local $1$hi i32)
+  (local $i64toi32_i32$0 i32)
+  (block $label$1
+   (unreachable)
+   (unreachable)
+  )
+  (block
+   (local.set $1
+    (block (result i32)
+     (local.set $i64toi32_i32$0
+      (local.get $0$hi)
+     )
+     (local.get $0)
+    )
+   )
+   (local.set $1$hi
+    (local.get $i64toi32_i32$0)
+   )
+  )
+  (block
+   (global.set $f
+    (block (result i32)
+     (local.set $i64toi32_i32$0
+      (local.get $1$hi)
+     )
+     (local.get $1)
+    )
+   )
+   (global.set $f$hi
+    (local.get $i64toi32_i32$0)
+   )
+  )
+  (nop)
+ )
 )

test/passes/flatten_i64-to-i32-lowering.wast

@@ -1,8 +1,29 @@
 (module
-  (import "env" "func" (func $import (result i64)))
-  (func $defined (result i64)
-    (i64.add (i64.const 1) (i64.const 2))
+ (import "env" "func" (func $import (result i64)))
+ (func $defined (result i64)
+  (i64.add (i64.const 1) (i64.const 2))
+ )
+ (func $unreachable-select-i64 (result i64)
+  (select
+   (i64.const 1)
+   (unreachable)
+   (i32.const 2)
+  )
+ )
+ (func $unreachable-select-i64-b (result i64)
+  (select
+   (unreachable)
+   (i64.const 3)
+   (i32.const 4)
+  )
+ )
+ (func $unreachable-select-i64-c (result i64)
+  (select
+   (i64.const 5)
+   (i64.const 6)
+   (unreachable)
   )
+ )
 )
 (module
  (global $f (mut i64) (i64.const 0x12345678ABCDEFAF))
@@ -12,4 +33,11 @@
   (call $call (global.get $f))
   (global.set $f (i64.const 0x1122334455667788))
  )
+ (func "unreach"
+  (global.set $f
+   (block $label$1 (result i64)
+    (unreachable)
+   )
+  )
+ )
 )

test/wasm2js/br.2asm.js

@@ -262,7 +262,7 @@ function asmFunc(global, env, buffer) {
  function $27($0, $1_1) {
   $0 = $0 | 0;
   $1_1 = $1_1 | 0;
-  var $2_1 = 0, $3_1 = 0, $4_1 = 0, $5_1 = 0, $6_1 = 0;
+  var $2_1 = 0, $3_1 = 0, $4_1 = 0;
   block : {
    $2_1 = 5;
    break block;
@@ -273,7 +273,7 @@ function asmFunc(global, env, buffer) {
  function $28($0, $1_1) {
   $0 = $0 | 0;
   $1_1 = $1_1 | 0;
-  var $2_1 = 0, $3_1 = 0, $4_1 = 0, $5_1 = 0, $6_1 = 0;
+  var $2_1 = 0, $3_1 = 0, $4_1 = 0;
   block : {
    $2_1 = $0;
    $3_1 = 6;

test/wasm2js/br_table.2asm.js

@@ -49727,7 +49727,7 @@ function asmFunc(global, env, buffer) {
  function $34($0, $1_1) {
   $0 = $0 | 0;
   $1_1 = $1_1 | 0;
-  var $3_1 = 0, $4_1 = 0, $5_1 = 0, $6_1 = 0, $7_1 = 0;
+  var $3_1 = 0, $4_1 = 0, $5_1 = 0;
   block : {
    $3_1 = 5;
    switch (0 | 0) {
@@ -49741,7 +49741,7 @@ function asmFunc(global, env, buffer) {
  function $35($0, $1_1) {
   $0 = $0 | 0;
   $1_1 = $1_1 | 0;
-  var $2_1 = 0, $4_1 = 0, $5_1 = 0, $6_1 = 0, $7_1 = 0;
+  var $2_1 = 0, $4_1 = 0, $5_1 = 0;
   block : {
    $2_1 = $0;
    $4_1 = 6;

test/wasm2js/br_table_temp.2asm.js

@@ -49725,7 +49725,7 @@ function asmFunc(global, env, buffer) {
  function $34($0, $1_1) {
   $0 = $0 | 0;
   $1_1 = $1_1 | 0;
-  var $3_1 = 0, $4_1 = 0, $5_1 = 0, $6_1 = 0, $7_1 = 0;
+  var $3_1 = 0, $4_1 = 0, $5_1 = 0;
   block : {
    $3_1 = 5;
    switch (0 | 0) {
@@ -49739,7 +49739,7 @@ function asmFunc(global, env, buffer) {
  function $35($0, $1_1) {
   $0 = $0 | 0;
   $1_1 = $1_1 | 0;
-  var $2_1 = 0, $4_1 = 0, $5_1 = 0, $6_1 = 0, $7_1 = 0;
+  var $2_1 = 0, $4_1 = 0, $5_1 = 0;
   block : {
    $2_1 = $0;
    $4_1 = 6;

test/wasm2js/i64-select.2asm.js

@@ -42,6 +42,18 @@ function asmFunc(global, env, buffer) {
   return i64toi32_i32$3 | 0;
  }
 
+ function unreachable_select_i64() {
+  return abort() | 0;
+ }
+
+ function unreachable_select_i64_b() {
+  return abort() | 0;
+ }
+
+ function unreachable_select_i64_c() {
+  return abort() | 0;
+ }
+
  var FUNCTION_TABLE = [];
  return {
 

test/wasm2js/i64-select.wast

@@ -20,4 +20,25 @@
    )   
   )    
  )
+ (func $unreachable-select-i64 (result i64)
+  (select
+   (i64.const 1)
+   (unreachable)
+   (i32.const 268435456)
+  )
+ )
+ (func $unreachable-select-i64-b (result i64)
+  (select
+   (unreachable)
+   (i64.const 1)
+   (i32.const 268435456)
+  )
+ )
+ (func $unreachable-select-i64-c (result i64)
+  (select
+   (i64.const 1)
+   (i64.const 1)
+   (unreachable)
+  )
+ )
 )

test/wasm2js/select.2asm.js

@@ -65,13 +65,13 @@ function asmFunc(global, env, buffer) {
 
  function $4(cond) {
   cond = cond | 0;
-  var $1_1 = 0, $2_1 = 0;
+  var $1_1 = 0;
   return abort() | 0;
  }
 
  function $5(cond) {
   cond = cond | 0;
-  var $1_1 = 0, $2_1 = 0;
+  var $1_1 = 0;
   return abort() | 0;
  }