[PATCH] D98884: [IR] Ignore bitcasts of function pointers which are only used as callees in callbase instruction

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec added a comment.

It looks fine to me with a style changes in couple places and positive checks in new tests.



================
Comment at: llvm/lib/IR/Function.cpp:1630
+          if (const CallBase *CB = dyn_cast<CallBase>(U.getUser()))
+            return CB->isCallee(&U);
+          return false;
----------------
foad wrote:
> This does not respect IgnoreCallbackUses, IgnoreAssumeLikeCalls, IgnoreLLVMUsed. Also it does not handle bitcasts-of-bitcasts.
> 
> Wouldn't the whole function be better implemented as a worklist algorithm now?
> ```
> SmallVector<Use &> WorkList(use_begin(), use_end());
> while (!WorkList.empty()) {
>   U = WorkList.pop_back_val();
>   if (isa<BitCast>(U))
>     WorkList.push_back(U.use_begin(), U.use_end());
>   else if (isa<CallBase>(U))
>     ... all the existing logic that handles Ignore* flags ...
> }
> ```
In general yes, but this patch is growing. This would be a good followup change.
The pass calls hasAddressTaken() without arguments so that is not exerciseable  here as is. For the same reason I withdraw my request to split the patch. Also note this may change if this is landed: D96179.


================
Comment at: llvm/lib/Transforms/IPO/GlobalOpt.cpp:2137
+  CallBase *CB = dyn_cast<CallBase>(UU);
+  if (!CB)
+    return;
----------------
A readbility change would be nice:
```
if (!CB && !CB->isCallee(&U))
  return
```




================
Comment at: llvm/lib/Transforms/IPO/GlobalOpt.cpp:2170
+  CallBase *CB = dyn_cast<CallBase>(U.getUser());
+  if (!CB)
+    return;
----------------
Same here: if (!CB && !CB->isCallee(&U))


================
Comment at: llvm/test/Transforms/GlobalOpt/assumelike-bitcast-fastcc.ll:13
+
+; CHECK-NOT: define internal fastcc void @bar() {
+define internal void @bar() {
----------------
You need to check something positive. You can just check it is 'define internal void @bar() {'.


================
Comment at: llvm/test/Transforms/GlobalOpt/bitcast-call-argument-fastcc.ll:9
+
+; CHECK-NOT: define internal fastcc i32 @foo() {
+define internal i32 @foo() {
----------------
Same here.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D98884/new/

https://reviews.llvm.org/D98884