[Attributor] FIX: Treat new attributes as changed ones

Summary:
When we have new attributes and we end the fixpoint iteration because
the iteration limit is reached, we need to treat the new ones as if they
changed in the last iteration, as they might have.

This adds a test for which we should not derive anything regardless of
the iteration limit, e.g., if we abort there should not be any
attributes manifested in the IR.

Reviewers: uenoku, sstefan1

Subscribers: hiraditya, bollu, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66549

llvm-svn: 369768

2 files changed, 48 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index 392a43ada74..373e491c846 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -2397,16 +2397,16 @@ ChangeStatus Attributor::run() {
         if (AA->update(*this) == ChangeStatus::CHANGED)
           ChangedAAs.push_back(AA);
 
+    // Add attributes to the changed set if they have been created in the last
+    // iteration.
+    ChangedAAs.append(AllAbstractAttributes.begin() + NumAAs,
+                      AllAbstractAttributes.end());
+
     // Reset the work list and repopulate with the changed abstract attributes.
     // Note that dependent ones are added above.
     Worklist.clear();
     Worklist.insert(ChangedAAs.begin(), ChangedAAs.end());
 
-    // Add attributes to the worklist that have been created in the last
-    // iteration.
-    Worklist.insert(AllAbstractAttributes.begin() + NumAAs,
-                    AllAbstractAttributes.end());
-
   } while (!Worklist.empty() && ++IterationCounter < MaxFixpointIterations);
 
   size_t NumFinalAAs = AllAbstractAttributes.size();
diff --git a/llvm/test/Transforms/FunctionAttrs/new_attributes.ll b/llvm/test/Transforms/FunctionAttrs/new_attributes.ll
new file mode 100644
index 00000000000..d2f6854bd3c
--- /dev/null
+++ b/llvm/test/Transforms/FunctionAttrs/new_attributes.ll
@@ -0,0 +1,43 @@
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations=0 -S | FileCheck %s
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations=1 -S | FileCheck %s
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations=2 -S | FileCheck %s
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations=3 -S | FileCheck %s
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations=4 -S | FileCheck %s
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations=2147483647 -S | FileCheck %s
+
+; CHECK-NOT: Function
+; CHECK: declare i32 @foo1()
+; CHECK-NOT: Function
+; CHECK: declare i32 @foo2()
+; CHECK-NOT: Function
+; CHECK: declare i32 @foo3()
+declare i32 @foo1()
+declare i32 @foo2()
+declare i32 @foo3()
+
+; CHECK-NOT: Function
+; CHECK:      define internal i32 @bar() {
+; CHECK-NEXT:   %1 = call i32 @foo1()
+; CHECK-NEXT:   %2 = call i32 @foo2()
+; CHECK-NEXT:   %3 = call i32 @foo3()
+; CHECK-NEXT:   ret i32 1
+; CHECK-NEXT: }
+define internal i32 @bar() {
+  %1 = call i32 @foo1()
+  %2 = call i32 @foo2()
+  %3 = call i32 @foo3()
+  ret i32 1
+}
+
+; CHECK-NOT: Function
+; CHECK:      define i32 @baz() {
+; CHECK-NEXT:   %1 = call i32 @bar()
+; CHECK-NEXT:   ret i32 0
+; CHECK-NEXT: }
+define i32 @baz() {
+  %1 = call i32 @bar()
+  ret i32 0
+}
+
+; We should never derive anything here
+; CHECK-NOT: attributes