[Attributor] Introudce attribute seed allow list.

llvm/include/llvm/Transforms/IPO/Attributor.h

@@ -891,6 +891,13 @@ struct Attributor {
     // No matching attribute found, create one.
     // Use the static create method.
     auto &AA = AAType::createForPosition(IRP, *this);
+
+    // If we are currenty seeding attributes, enforce seeding rules.
+    if (SeedingPeriod && !shouldSeedAttribute(AA)) {
+      AA.getState().indicatePessimisticFixpoint();
+      return AA;
+    }
+
     registerAA(AA);
 
     // For now we ignore naked and optnone functions.
@@ -918,8 +925,15 @@ struct Attributor {
       return AA;
     }
 
+    // Allow seeded attributes to declare dependencies.
+    // Remember the seeding state.
+    bool OldSeedingPeriod = SeedingPeriod;
+    SeedingPeriod = false;
+
     updateAA(AA);
 
+    SeedingPeriod = OldSeedingPeriod;
+
     if (TrackDependence && AA.getState().isValidState())
       recordDependence(AA, const_cast<AbstractAttribute &>(*QueryingAA),
                        DepClass);
@@ -1345,6 +1359,10 @@ private:
   ChangeStatus
   rewriteFunctionSignatures(SmallPtrSetImpl<Function *> &ModifiedFns);
 
+  /// Check if the Attribute \p AA should be seeded.
+  /// See getOrCreateAAFor.
+  bool shouldSeedAttribute(AbstractAttribute &AA);
+
   /// The set of all abstract attributes.
   ///{
   using AAVector = SmallVector<AbstractAttribute *, 64>;
@@ -1410,6 +1428,10 @@ private:
   /// Invoke instructions with at least a single dead successor block.
   SmallVector<WeakVH, 16> InvokeWithDeadSuccessor;
 
+  /// Wheather attributes are being `seeded`, always false after ::run function
+  /// gets called \see getOrCreateAAFor.
+  bool SeedingPeriod = true;
+
   /// Functions, blocks, and instructions we delete after manifest is done.
   ///
   ///{

llvm/lib/Transforms/IPO/Attributor.cpp

@@ -78,6 +78,12 @@ static cl::opt<bool>
                                   "wrappers for non-exact definitions."),
                          cl::init(false));
 
+static cl::list<std::string>
+    SeedAllowList("attributor-seed-allow-list", cl::Hidden,
+                  cl::desc("Comma seperated list of attrbute names that are "
+                           "allowed to be seeded."),
+                  cl::ZeroOrMore, cl::CommaSeparated);
+
 /// Logic operators for the change status enum class.
 ///
 ///{
@@ -1256,6 +1262,7 @@ ChangeStatus Attributor::cleanupIR() {
 }
 
 ChangeStatus Attributor::run() {
+  SeedingPeriod = false;
   runTillFixpoint();
   ChangeStatus ManifestChange = manifestAttributes();
   ChangeStatus CleanupChange = cleanupIR();
@@ -1452,6 +1459,12 @@ bool Attributor::registerFunctionSignatureRewrite(
   return true;
 }
 
+bool Attributor::shouldSeedAttribute(AbstractAttribute &AA) {
+  if (SeedAllowList.size() == 0)
+    return true;
+  return std::count(SeedAllowList.begin(), SeedAllowList.end(), AA.getName());
+}
+
 ChangeStatus Attributor::rewriteFunctionSignatures(
     SmallPtrSetImpl<Function *> &ModifiedFns) {
   ChangeStatus Changed = ChangeStatus::UNCHANGED;

llvm/test/Transforms/Attributor/allow_list.ll

@@ -0,0 +1,33 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --scrub-attributes
+; RUN: opt -S -passes=attributor --attributor-seed-allow-list asd < %s | FileCheck %s --check-prefixes=CHECK_DISABLED
+; RUN: opt -S -passes=attributor --attributor-seed-allow-list AAValueSimplify < %s | FileCheck %s --check-prefixes=CHECK_ENABLED
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+; Function Attrs: nounwind uwtable
+define internal i32 @range_test(i32 %a) #0 {
+; CHECK_DISABLED-LABEL: define {{[^@]+}}@range_test
+; CHECK_DISABLED-SAME: (i32 [[A:%.*]])
+; CHECK_DISABLED-NEXT:    [[TMP1:%.*]] = icmp sgt i32 [[A]], 100
+; CHECK_DISABLED-NEXT:    [[TMP2:%.*]] = zext i1 [[TMP1]] to i32
+; CHECK_DISABLED-NEXT:    ret i32 [[TMP2]]
+;
+  %1 = icmp sgt i32 %a, 100
+  %2 = zext i1 %1 to i32
+  ret i32 %2
+}
+
+; Function Attrs: nounwind uwtable
+define i32 @range_use() #0 {
+; CHECK_DISABLED-LABEL: define {{[^@]+}}@range_use()
+; CHECK_DISABLED-NEXT:    [[TMP1:%.*]] = call i32 @range_test(i32 123)
+; CHECK_DISABLED-NEXT:    ret i32 [[TMP1]]
+;
+; CHECK_ENABLED-LABEL: define {{[^@]+}}@range_use()
+; CHECK_ENABLED-NEXT:    ret i32 1
+;
+  %1 = call i32 @range_test(i32 123)
+  ret i32 %1
+}
+
+attributes #0 = { nounwind uwtable noinline }