Handle indirect calls in CallGraphPropertyAnalysis (#2624)

We ignored them, which is a bad default, as typically they imply
we can call anything in the table (and the table might change).
Instead, notice indirect calls during traversal, and force the user
to decide whether to ignore them or not.

This was only an issue in PostEmscripten because the other
user, Asyncify, already had indirect call analysis because it
needed it for other things.

Fixes a bug uncovered by #2619 and fixes the current binaryen
roll.

Author: kripken

src/ir/module-utils.h

@@ -341,6 +341,7 @@ template<typename T> struct CallGraphPropertyAnalysis {
   struct FunctionInfo {
     std::set<Function*> callsTo;
     std::set<Function*> calledBy;
+    bool hasIndirectCall = false;
   };
 
   typedef std::map<Function*, T> Map;
@@ -362,6 +363,10 @@ template<typename T> struct CallGraphPropertyAnalysis {
           info.callsTo.insert(module->getFunction(curr->target));
         }
 
+        void visitCallIndirect(CallIndirect* curr) {
+          info.hasIndirectCall = true;
+        }
+
       private:
         Module* module;
         T& info;
@@ -382,14 +387,20 @@ template<typename T> struct CallGraphPropertyAnalysis {
     }
   }
 
+  enum IndirectCalls { IgnoreIndirectCalls, IndirectCallsHaveProperty };
+
   // Propagate a property from a function to those that call it.
   void propagateBack(std::function<bool(const T&)> hasProperty,
                      std::function<bool(const T&)> canHaveProperty,
-                     std::function<void(T&)> addProperty) {
+                     std::function<void(T&)> addProperty,
+                     IndirectCalls indirectCalls) {
     // The work queue contains items we just learned can change the state.
     UniqueDeferredQueue<Function*> work;
     for (auto& func : wasm.functions) {
-      if (hasProperty(map[func.get()])) {
+      if (hasProperty(map[func.get()]) ||
+          (indirectCalls == IndirectCallsHaveProperty &&
+           map[func.get()].hasIndirectCall)) {
+        addProperty(map[func.get()]);
         work.push(func.get());
       }
     }

src/passes/Asyncify.cpp

@@ -549,7 +549,8 @@ class ModuleAnalyzer {
                             return !info.isBottomMostRuntime &&
                                    !info.inBlacklist;
                           },
-                          [](Info& info) { info.canChangeState = true; });
+                          [](Info& info) { info.canChangeState = true; },
+                          scanner.IgnoreIndirectCalls);
 
     map.swap(scanner.map);
 

src/passes/PostEmscripten.cpp

@@ -154,9 +154,11 @@ struct PostEmscripten : public Pass {
         }
       });
 
+    // Assume an indirect call might throw.
     analyzer.propagateBack([](const Info& info) { return info.canThrow; },
                            [](const Info& info) { return true; },
-                           [](Info& info) { info.canThrow = true; });
+                           [](Info& info) { info.canThrow = true; },
+                           analyzer.IndirectCallsHaveProperty);
 
     // Apply the information.
     struct OptimizeInvokes : public WalkerPass<PostWalker<OptimizeInvokes>> {

test/passes/post-emscripten.txt

@@ -152,3 +152,27 @@
   (nop)
  )
 )
+(module
+ (type $none_=>_none (func))
+ (type $i32_i32_f32_=>_none (func (param i32 i32 f32)))
+ (type $i32_f32_=>_none (func (param i32 f32)))
+ (type $f64_f64_=>_f64 (func (param f64 f64) (result f64)))
+ (import "env" "glob" (global $glob i32))
+ (import "global.Math" "pow" (func $Math_pow (param f64 f64) (result f64)))
+ (import "env" "invoke_vif" (func $invoke_vif (param i32 i32 f32)))
+ (memory $0 256 256)
+ (table $0 7 7 funcref)
+ (elem (i32.const 0) $other_safe)
+ (func $exc (; 2 ;)
+  (call $invoke_vif
+   (i32.const 0)
+   (i32.const 42)
+   (f32.const 3.141590118408203)
+  )
+ )
+ (func $other_safe (; 3 ;) (param $0 i32) (param $1 f32)
+  (call_indirect (type $none_=>_none)
+   (i32.const 0)
+  )
+ )
+)

test/passes/post-emscripten.wast

@@ -109,7 +109,7 @@
     (call $call)
   )
 )
-(module
+(module ;; non-constant base for elem
   (type $0 (func (param i32)))
   (import "global.Math" "pow" (func $Math_pow (param f64 f64) (result f64)))
   (import "env" "invoke_vif" (func $invoke_vif (param i32 i32 f32)))
@@ -127,3 +127,24 @@
   (func $other_safe (param i32) (param f32)
   )
 )
+(module ;; indirect call in the invoke target, which we assume might throw
+  (type $none_=>_none (func))
+  (import "global.Math" "pow" (func $Math_pow (param f64 f64) (result f64)))
+  (import "env" "invoke_vif" (func $invoke_vif (param i32 i32 f32)))
+  (import "env" "glob" (global $glob i32)) ;; non-constant table offset
+  (memory 256 256)
+  (table 7 7 funcref)
+  (elem (i32.const 0) $other_safe)
+  (func $exc
+    (call $invoke_vif
+      (i32.const 0) ;; other_safe()
+      (i32.const 42)
+      (f32.const 3.14159)
+    )
+  )
+  (func $other_safe (param i32) (param f32)
+   (call_indirect (type $none_=>_none)
+    (i32.const 0)
+   )
+  )
+)