[Attributor] AANoRecurse check all call sites for `norecurse`

If all call sites are in `norecurse` functions we can derive `norecurse`
as the ReversePostOrderFunctionAttrsPass does. This should make
ReversePostOrderFunctionAttrsLegacyPass obsolete once the Attributor is
enabled.

Reviewed By: uenoku

Differential Revision: https://reviews.llvm.org/D72017

llvm/lib/Transforms/IPO/Attributor.cpp

@@ -2082,14 +2082,33 @@ struct AANoRecurseFunction final : AANoRecurseImpl {
   void initialize(Attributor &A) override {
     AANoRecurseImpl::initialize(A);
     if (const Function *F = getAnchorScope())
-      if (A.getInfoCache().getSccSize(*F) == 1)
-        return;
-    indicatePessimisticFixpoint();
+      if (A.getInfoCache().getSccSize(*F) != 1)
+        indicatePessimisticFixpoint();
   }
 
   /// See AbstractAttribute::updateImpl(...).
   ChangeStatus updateImpl(Attributor &A) override {
 
+    // If all live call sites are known to be no-recurse, we are as well.
+    auto CallSitePred = [&](AbstractCallSite ACS) {
+      const auto &NoRecurseAA = A.getAAFor<AANoRecurse>(
+          *this, IRPosition::function(*ACS.getInstruction()->getFunction()),
+          /* TrackDependence */ false, DepClassTy::OPTIONAL);
+      return NoRecurseAA.isKnownNoRecurse();
+    };
+    bool AllCallSitesKnown;
+    if (A.checkForAllCallSites(CallSitePred, *this, true, AllCallSitesKnown)) {
+      // If we know all call sites and all are known no-recurse, we are done.
+      // If all known call sites, which might not be all that exist, are known
+      // to be no-recurse, we are not done but we can continue to assume
+      // no-recurse. If one of the call sites we have not visited will become
+      // live, another update is triggered.
+      if (AllCallSitesKnown)
+        indicateOptimisticFixpoint();
+      return ChangeStatus::UNCHANGED;
+    }
+
+    // If the above check does not hold anymore we look at the calls.
     auto CheckForNoRecurse = [&](Instruction &I) {
       ImmutableCallSite ICS(&I);
       if (ICS.hasFnAttr(Attribute::NoRecurse))

llvm/test/Transforms/Attributor/ArgumentPromotion/dbg.ll

@@ -30,7 +30,7 @@ define void @caller(i32** %Y, %struct.pair* %P) {
 ; CHECK-LABEL: define {{[^@]+}}@caller
 ; CHECK-SAME: (i32** nocapture readonly [[Y:%.*]], %struct.pair* nocapture nofree readonly [[P:%.*]])
 ; CHECK-NEXT:    call void @test(i32** nocapture readonly align 8 [[Y]]), !dbg !4
-; CHECK-NEXT:    call void @test_byval(), !dbg !5
+; CHECK-NEXT:    call void @test_byval() #1, !dbg !5
 ; CHECK-NEXT:    ret void
 ;
   call void @test(i32** %Y), !dbg !1

llvm/test/Transforms/Attributor/ArgumentPromotion/nonzero-address-spaces.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --scrub-attributes
-; RUN: opt -S -passes=attributor -aa-pipeline='basic-aa' -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=1 < %s | FileCheck %s
+; RUN: opt -S -passes=attributor -aa-pipeline='basic-aa' -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=2 < %s | FileCheck %s
 
 ; ArgumentPromotion should preserve the default function address space
 ; from the data layout.

llvm/test/Transforms/Attributor/IPConstantProp/multiple_callbacks.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --scrub-attributes
-; RUN: opt -S -passes=attributor -aa-pipeline='basic-aa' -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=1 < %s | FileCheck %s
+; RUN: opt -S -passes=attributor -aa-pipeline='basic-aa' -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=3 < %s | FileCheck %s
 ;
 ;
 ;                            /---------------------------------------|

llvm/test/Transforms/Attributor/internal-noalias.ll

@@ -1,4 +1,4 @@
-; RUN: opt -S -passes=attributor -aa-pipeline='basic-aa' -attributor-disable=false -attributor-max-iterations-verify -attributor-annotate-decl-cs -attributor-max-iterations=5 < %s | FileCheck %s
+; RUN: opt -S -passes=attributor -aa-pipeline='basic-aa' -attributor-disable=false -attributor-max-iterations-verify -attributor-annotate-decl-cs -attributor-max-iterations=6 < %s | FileCheck %s
 
 define dso_local i32 @visible(i32* noalias %A, i32* noalias %B) #0 {
 entry:

llvm/test/Transforms/Attributor/norecurse.ll

@@ -1,4 +1,4 @@
-; RUN: opt -passes=attributor --attributor-disable=false -attributor-max-iterations-verify -attributor-annotate-decl-cs -attributor-max-iterations=2 -S < %s | FileCheck %s --check-prefixes=ATTRIBUTOR
+; RUN: opt -passes=attributor --attributor-disable=false -attributor-max-iterations-verify -attributor-annotate-decl-cs -attributor-max-iterations=4 -S < %s | FileCheck %s --check-prefixes=ATTRIBUTOR
 ; Copied from Transforms/FunctoinAttrs/norecurse.ll
 
 ; ATTRIBUTOR: Function Attrs: nofree norecurse nosync nounwind readnone willreturn
@@ -59,8 +59,7 @@ define void @intrinsic(i8* %dest, i8* %src, i32 %len) {
 declare void @llvm.memcpy.p0i8.p0i8.i32(i8*, i8*, i32, i1)
 
 ; ATTRIBUTOR: Function Attrs
-; FIXME: missing "norecurse"
-; ATTRIBUTOR-SAME: nosync readnone
+; ATTRIBUTOR-SAME: norecurse nosync readnone
 define internal i32 @called_by_norecurse() {
   %a = call i32 @k()
   ret i32 %a
@@ -73,19 +72,22 @@ define void @m() norecurse {
 }
 
 ; ATTRIBUTOR: Function Attrs
-; FIXME: missing "norecurse"
-; ATTRIBUTOR-SAME: nosync
+; ATTRIBUTOR-SAME: norecurse nosync readnone
+; ATTRIBUTOR-NEXT: @called_by_norecurse_indirectly
 define internal i32 @called_by_norecurse_indirectly() {
   %a = call i32 @k()
   ret i32 %a
 }
-define internal void @o() {
+; ATTRIBUTOR: Function Attrs
+; ATTRIBUTOR-SAME: norecurse nosync readnone
+; ATTRIBUTOR-NEXT: @o
+define internal i32 @o() {
   %a = call i32 @called_by_norecurse_indirectly()
-  ret void
+  ret i32 %a
 }
-define void @p() norecurse {
-  call void @o()
-  ret void
+define i32 @p() norecurse {
+  %a = call i32 @o()
+  ret i32 %a
 }
 
 ; ATTRIBUTOR: Function Attrs: nofree nosync nounwind