[PATCH] D128104: [RPOFuncAttrs] Fix norecurse detection

[Arthur Eubanks via Phabricator via llvm-commits]

aeubanks created this revision.
aeubanks added reviewers: asbirlea, nikic.
Herald added subscribers: ormris, hiraditya.
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We wanted to check if all uses of the function are direct calls, but the
code didn't account for passing the function as a parameter.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D128104

Files:
  llvm/lib/Transforms/IPO/FunctionAttrs.cpp
  llvm/test/Transforms/FunctionAttrs/norecurse.ll


Index: llvm/test/Transforms/FunctionAttrs/norecurse.ll
===================================================================
--- llvm/test/Transforms/FunctionAttrs/norecurse.ll
+++ llvm/test/Transforms/FunctionAttrs/norecurse.ll
@@ -99,7 +99,9 @@
 }
 
 ; CHECK: Function Attrs
-; CHECK-SAME: norecurse nosync readnone
+; CHECK-NOT: norecurse
+; CHECK-SAME: nosync readnone
+; CHECK-NOT: norecurse
 ; CHECK-NEXT: define internal i32 @escapes_as_parameter
 define internal i32 @escapes_as_parameter(ptr %p) {
   %a = call i32 @k()
Index: llvm/lib/Transforms/IPO/FunctionAttrs.cpp
===================================================================
--- llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -2014,12 +2014,13 @@
   // this function could be recursively (indirectly) called. Note that this
   // also detects if F is directly recursive as F is not yet marked as
   // a norecurse function.
-  for (auto *U : F.users()) {
-    auto *I = dyn_cast<Instruction>(U);
+  for (auto &U : F.uses()) {
+    auto *I = dyn_cast<Instruction>(U.getUser());
     if (!I)
       return false;
     CallBase *CB = dyn_cast<CallBase>(I);
-    if (!CB || !CB->getParent()->getParent()->doesNotRecurse())
+    if (!CB || !CB->isCallee(&U) ||
+        !CB->getParent()->getParent()->doesNotRecurse())
       return false;
   }
   F.setDoesNotRecurse();


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