drop norecurse change for now

Author: nikic

llvm/lib/Transforms/IPO/FunctionAttrs.cpp

@@ -2086,13 +2086,11 @@ static void addNoRecurseAttrs(const SCCNodeSet &SCCNodes,
   for (auto &BB : *F)
     for (auto &I : BB.instructionsWithoutDebug())
       if (auto *CB = dyn_cast<CallBase>(&I)) {
-        if (CB->hasFnAttr(Attribute::NoRecurse))
-          continue;
-
         Function *Callee = CB->getCalledFunction();
         if (!Callee || Callee == F ||
-            !(Callee->isDeclaration() &&
-              Callee->hasFnAttribute(Attribute::NoCallback)))
+            (!Callee->doesNotRecurse() &&
+             !(Callee->isDeclaration() &&
+               Callee->hasFnAttribute(Attribute::NoCallback))))
           // Function calls a potentially recursive function.
           return;
       }

llvm/test/Transforms/FunctionAttrs/norecurse.ll

@@ -258,10 +258,9 @@ define void @unknown_call(ptr %fn) {
 }
 
 define void @unknown_norecurse_call(ptr %fn) {
-; FNATTRS: Function Attrs: norecurse
 ; FNATTRS-LABEL: define {{[^@]+}}@unknown_norecurse_call
-; FNATTRS-SAME: (ptr readonly captures(none) [[FN:%.*]]) #[[ATTR7:[0-9]+]] {
-; FNATTRS-NEXT:    call void [[FN]]() #[[ATTR7]]
+; FNATTRS-SAME: (ptr readonly captures(none) [[FN:%.*]]) {
+; FNATTRS-NEXT:    call void [[FN]]() #[[ATTR7:[0-9]+]]
 ; FNATTRS-NEXT:    ret void
 ;
 ; ATTRIBUTOR-LABEL: define {{[^@]+}}@unknown_norecurse_call