[PATCH] D60075: [FunctionAttrs] Remove post order "no-recurse" attribute deduction

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert updated this revision to Diff 203164.
jdoerfert added a comment.

Update tests


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60075/new/

https://reviews.llvm.org/D60075

Files:
  llvm/lib/Transforms/IPO/FunctionAttrs.cpp
  llvm/test/Transforms/FunctionAttrs/arg_returned.ll
  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
@@ -90,8 +90,9 @@
   ret void
 }
 
-; FIXME: This test exposes a bug: https://llvm.org/PR41336
-; CHECK: Function Attrs: norecurse
+; PR41336
+; CHECK: Function Attrs:
+; CHECK-NOT: norecurse
 ; CHECK-NEXT: define i32 @leaf_redefinable()
 define linkonce_odr i32 @leaf_redefinable() {
   ret i32 1
Index: llvm/test/Transforms/FunctionAttrs/arg_returned.ll
===================================================================
--- llvm/test/Transforms/FunctionAttrs/arg_returned.ll
+++ llvm/test/Transforms/FunctionAttrs/arg_returned.ll
@@ -308,17 +308,11 @@
 ;
 ; Verify the maybe-redefined function is not annotated:
 ;
-; CHECK: Function Attrs: noinline norecurse nounwind uwtable
+; CHECK: Function Attrs: noinline nounwind uwtable
 ; CHECK: define linkonce_odr i32* @maybe_redefined_fn(i32* %r)
-; FIXME: We should not derive norecurse for potentially redefined functions!
-;        Function Attrs: noinline nounwind uwtable
-;        define linkonce_odr i32* @maybe_redefined_fn(i32* %r)
 ;
-; CHECK: Function Attrs: noinline norecurse nounwind uwtable
+; CHECK: Function Attrs: noinline nounwind uwtable
 ; CHECK: define i32* @calls_maybe_redefined_fn(i32* returned %r)
-; FIXME: We should not derive norecurse for potentially redefined functions!
-;        Function Attrs: noinline nounwind uwtable
-;        define i32* @calls_maybe_redefined_fn(i32* returned %r)
 define linkonce_odr i32* @maybe_redefined_fn(i32* %r) #0 {
 entry:
   ret i32* %r
Index: llvm/lib/Transforms/IPO/FunctionAttrs.cpp
===================================================================
--- llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -210,7 +210,7 @@
     ReadsMemory |= I->mayReadFromMemory();
   }
 
-  if (WritesMemory) { 
+  if (WritesMemory) {
     if (!ReadsMemory)
       return MAK_WriteOnly;
     else
@@ -1292,35 +1292,6 @@
   return true;
 }
 
-static bool addNoRecurseAttrs(const SCCNodeSet &SCCNodes) {
-  // Try and identify functions that do not recurse.
-
-  // If the SCC contains multiple nodes we know for sure there is recursion.
-  if (SCCNodes.size() != 1)
-    return false;
-
-  Function *F = *SCCNodes.begin();
-  if (!F || F->isDeclaration() || F->doesNotRecurse())
-    return false;
-
-  // If all of the calls in F are identifiable and are to norecurse functions, F
-  // is norecurse. This check also detects self-recursion as F is not currently
-  // marked norecurse, so any called from F to F will not be marked norecurse.
-  for (auto &BB : *F)
-    for (auto &I : BB.instructionsWithoutDebug())
-      if (auto CS = CallSite(&I)) {
-        Function *Callee = CS.getCalledFunction();
-        if (!Callee || Callee == F || !Callee->doesNotRecurse())
-          // Function calls a potentially recursive function.
-          return false;
-      }
-
-  // Every call was to a non-recursive function other than this function, and
-  // we have no indirect recursion as the SCC size is one. This function cannot
-  // recurse.
-  return setDoesNotRecurse(*F);
-}
-
 template <typename AARGetterT>
 static bool deriveAttrsInPostOrder(SCCNodeSet &SCCNodes, AARGetterT &&AARGetter,
                                    bool HasUnknownCall) {
@@ -1340,7 +1311,6 @@
     Changed |= addNoAliasAttrs(SCCNodes);
     Changed |= addNonNullAttrs(SCCNodes);
     Changed |= inferAttrsFromFunctionBodies(SCCNodes);
-    Changed |= addNoRecurseAttrs(SCCNodes);
   }
 
   return Changed;


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