Use TrapsNeverHappen mode in more places in Vacuum (#4117)

We had already replaced the check on drop, but we can also
use that mode on all the other things there, as the pass never
does reorderings of things - it just removes them.

For example, the pass can now remove part of a dropped thing,

(drop (struct.get (foo)))
=>
(drop (foo))

In this example the struct.get can be removed, even if the foo
can't.

2 files changed, 4 insertions, 4 deletions

diff --git a/src/ir/effects.h b/src/ir/effects.h
index 3f0f78e6f..b9393ade2 100644
--- a/src/ir/effects.h
+++ b/src/ir/effects.h
@@ -169,7 +169,7 @@ public:
   // and gets the result that there are no unremovable side effects, then it
   // must either
   //
-  //  1. Remove any side effects present, if any, so they no longer exists.
+  //  1. Remove any side effects present, if any, so they no longer exist.
   //  2. Keep the code exactly where it is.
   //
   // If instead of 1&2 a pass kept the side effect and also reordered the code
diff --git a/src/passes/Vacuum.cpp b/src/passes/Vacuum.cpp
index dec4add01..abd54f334 100644
--- a/src/passes/Vacuum.cpp
+++ b/src/passes/Vacuum.cpp
@@ -103,7 +103,7 @@ struct Vacuum : public WalkerPass<ExpressionStackWalker<Vacuum>> {
       // Check if this expression itself has side effects, ignoring children.
       EffectAnalyzer self(getPassOptions(), *getModule());
       self.visit(curr);
-      if (self.hasSideEffects()) {
+      if (self.hasUnremovableSideEffects()) {
         return curr;
       }
       // The result isn't used, and this has no side effects itself, so we can
@@ -111,7 +111,7 @@ struct Vacuum : public WalkerPass<ExpressionStackWalker<Vacuum>> {
       SmallVector<Expression*, 1> childrenWithEffects;
       for (auto* child : ChildIterator(curr)) {
         if (EffectAnalyzer(getPassOptions(), *getModule(), child)
-              .hasSideEffects()) {
+              .hasUnremovableSideEffects()) {
           childrenWithEffects.push_back(child);
         }
       }
@@ -378,7 +378,7 @@ struct Vacuum : public WalkerPass<ExpressionStackWalker<Vacuum>> {
     }
     if (curr->getResults() == Type::none &&
         !EffectAnalyzer(getPassOptions(), *getModule(), curr->body)
-           .hasSideEffects()) {
+           .hasUnremovableSideEffects()) {
       ExpressionManipulator::nop(curr->body);
     }
   }