[Attributor] Adjust and test the iteration bound of tests

[jdoerfert]

Summary

Try to verify how many iterations we need for a fixpoint in our tests.
This patch adjust the way we count to make it easier to follow. It also
adjusts the bounds to actually account for a fixpoint and not only the
minimum number to pass all checks.

[uenoku]

LGTM

llvm/lib/Transforms/IPO/Attributor.cpp

 // that we never reach 32 iterations but always find a fixpoint sooner.
 //
 // This will become more evolved once we perform two interleaved fixpoint
 // iterations: bottom-up and top-down.
 static cl::opt<unsigned>
     MaxFixpointIterations("attributor-max-iterations", cl::Hidden,
                           cl::desc("Maximal number of fixpoint iterations."),
                           cl::init(32));
+static cl::opt<bool> VerifyMaxFixpointIterations(
+    "attributor-max-iterations-verify", cl::Hidden,
+    cl::desc("Verify that max-iterations is a tight bound for a fixpoint"),
+    cl::init(false));
 
 static cl::opt<bool> DisableAttributor(
     "attributor-disable", cl::Hidden,
     cl::desc("Disable the attributor inter-procedural deduction pass."),
     cl::init(true));
 
 static cl::opt<bool> VerifyAttributor(
     "attributor-verify", cl::Hidden,
do {
 
     // Add all abstract attributes that are potentially dependent on one that
     // changed to the work list.
     for (AbstractAttribute *ChangedAA : ChangedAAs) {
       auto &QuerriedAAs = QueryMap[ChangedAA];
       Worklist.insert(QuerriedAAs.begin(), QuerriedAAs.end());
     }
 
+    LLVM_DEBUG(dbgs() << "[Attributor] #Iteration: " << IterationCounter
+                      << ", Worklist+Dependent size: " << Worklist.size()
+                      << "\n");
+
     // Reset the changed set.
     ChangedAAs.clear();
 
     // Update all abstract attribute in the work list and record the ones that
     // changed.
     for (AbstractAttribute *AA : Worklist)
       if (!isAssumedDead(*AA, nullptr))
         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());
 
-  } while (!Worklist.empty() && ++IterationCounter < MaxFixpointIterations);
+  } while (!Worklist.empty() && IterationCounter++ < MaxFixpointIterations);
 
   size_t NumFinalAAs = AllAbstractAttributes.size();
 
   LLVM_DEBUG(dbgs() << "\n[Attributor] Fixpoint iteration done after: "
                     << IterationCounter << "/" << MaxFixpointIterations
                     << " iterations\n");
 
+  if (VerifyMaxFixpointIterations && IterationCounter != MaxFixpointIterations)
+    llvm_unreachable("The fixpoint was not reached with exactly the number of "
+                     "specified iterations!");
+
   bool FinishedAtFixpoint = Worklist.empty();
 
   // Reset abstract arguments not settled in a sound fixpoint by now. This
   // happens when we stopped the fixpoint iteration early. Note that only the
   // ones marked as "changed" *and* the ones transitively depending on them
   // need to be reverted to a pessimistic state. Others might not be in a
   // fixpoint state but we can use the optimistic results for them anyway.
   SmallPtrSet<AbstractAttribute *, 32> Visited;

llvm/test/Transforms/FunctionAttrs/align.ll

-; RUN: opt -attributor -attributor-disable=false -attributor-max-iterations=32 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
+; RUN: opt -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=17 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
 ; Test cases specifically designed for "align" attribute.
 ; We use FIXME's to indicate problems and missing attributes.
 
 
 ; TEST 1

llvm/test/Transforms/FunctionAttrs/arg_nocapture.ll

-; RUN: opt -functionattrs -attributor -attributor-disable=false -attributor-max-iterations=19 -S < %s | FileCheck %s
+; RUN: opt -functionattrs -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=18 -S < %s | FileCheck %s
 ;
 ; Test cases specifically designed for the "no-capture" argument attribute.
 ; We use FIXME's to indicate problems and missing attributes.
 ;
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
 ; TEST comparison against NULL
 ;

llvm/test/Transforms/FunctionAttrs/arg_returned.ll

 ; RUN: opt -functionattrs -S < %s | FileCheck %s --check-prefix=FNATTR
-; RUN: opt -attributor -attributor-disable=false -attributor-max-iterations=27 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
+; RUN: opt -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=26 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
 ; RUN: opt -attributor -attributor-disable=false -functionattrs -S < %s | FileCheck %s --check-prefix=BOTH
 ;
 ; Test cases specifically designed for the "returned" argument attribute.
 ; We use FIXME's to indicate problems and missing attributes.
 ;
 
 ; TEST SCC test returning an integer value argument
 ;

llvm/test/Transforms/FunctionAttrs/dereferenceable.ll

-; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations=4 -S < %s | FileCheck %s --check-prefixes=ATTRIBUTOR
+; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=5 -S < %s | FileCheck %s --check-prefixes=ATTRIBUTOR
 
 
 declare void @deref_phi_user(i32* %a);
 
 ; TEST 1
 ; take mininimum of return values
 ;
 define i32* @test1(i32* dereferenceable(4) %0, double* dereferenceable(8) %1, i1 zeroext %2) local_unnamed_addr {

llvm/test/Transforms/FunctionAttrs/fn_noreturn.ll

-; RUN: opt -functionattrs -attributor -attributor-disable=false -attributor-max-iterations=3 -S < %s | FileCheck %s
+; RUN: opt -functionattrs -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=4 -S < %s | FileCheck %s
 ;
 ; Test cases specifically designed for the "no-return" function attribute.
 ; We use FIXME's to indicate problems and missing attributes.
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
 
 ; TEST 1, singleton SCC void return type

llvm/test/Transforms/FunctionAttrs/liveness.ll

-; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations=6 -S < %s | FileCheck %s
+; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=6 -S < %s | FileCheck %s
 
 declare void @no_return_call() nofree noreturn nounwind readnone
 
 declare void @normal_call() readnone
 
 declare i32 @foo()
 
 declare i32 @foo_noreturn_nounwind() noreturn nounwind

llvm/test/Transforms/FunctionAttrs/new_attributes.ll

-; 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
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=0 -S | FileCheck %s
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=1 -S | FileCheck %s
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=2 -S | FileCheck %s
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=3 -S | FileCheck %s
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=4 -S | FileCheck %s
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations-verify -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()

llvm/test/Transforms/FunctionAttrs/noalias_returned.ll

-; RUN: opt -S -attributor -attributor-disable=false -attributor-max-iterations=8 < %s | FileCheck %s
+; RUN: opt -S -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=8 < %s | FileCheck %s
 
 ; TEST 1 - negative.
 
 ; void *G;
 ; void *foo(){
 ;   void *V = malloc(4);
 ;   G = V;
 ;   return V;

llvm/test/Transforms/FunctionAttrs/nofree-attributor.ll

 ; RUN: opt -functionattrs --disable-nofree-inference=false -S < %s | FileCheck %s --check-prefix=FNATTR
-; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations=4 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
+; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=8 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
 ; Test cases specifically designed for the "nofree" function attribute.
 ; We use FIXME's to indicate problems and missing attributes.
 
 ; Free functions
 declare void @free(i8* nocapture) local_unnamed_addr #1

llvm/test/Transforms/FunctionAttrs/nonnull.ll

 ; RUN: opt -S -functionattrs -enable-nonnull-arg-prop %s | FileCheck %s --check-prefixes=BOTH,FNATTR
 ; RUN: opt -S -passes=function-attrs -enable-nonnull-arg-prop %s | FileCheck %s --check-prefixes=BOTH,FNATTR
-; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations=32 -S < %s | FileCheck %s --check-prefixes=BOTH,ATTRIBUTOR
+; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=12 -S < %s | FileCheck %s --check-prefixes=BOTH,ATTRIBUTOR
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
 declare nonnull i8* @ret_nonnull()
 
 ; Return a pointer trivially nonnull (call return attribute)
 define i8* @test1() {
 ; BOTH: define nonnull i8* @test1

llvm/test/Transforms/FunctionAttrs/noreturn_async.ll

-; RUN: opt -functionattrs -attributor -attributor-disable=false -attributor-max-iterations=5 -S < %s | FileCheck %s
+; RUN: opt -functionattrs -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=4 -S < %s | FileCheck %s
 ;
 ; This file is the same as noreturn_sync.ll but with a personality which
 ; indicates that the exception handler *can* catch asynchronous exceptions. As
 ; a consequence, invokes to noreturn and nounwind functions are not translated
 ; to calls followed by an unreachable but the unwind edge is considered live.
 ;
 ; https://reviews.llvm.org/D59978#inline-586873
 ;

llvm/test/Transforms/FunctionAttrs/noreturn_sync.ll

-; RUN: opt -functionattrs -attributor -attributor-disable=false -attributor-max-iterations=32 -S < %s | FileCheck %s
+; RUN: opt -functionattrs -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=7 -S < %s | FileCheck %s
 ;
 ; This file is the same as noreturn_async.ll but with a personality which
 ; indicates that the exception handler *cannot* catch asynchronous exceptions.
 ; As a consequence, invokes to noreturn and nounwind functions are translated
 ; to calls followed by an unreachable.
 ;
 ; https://reviews.llvm.org/D59978#inline-586873
 ;

llvm/test/Transforms/FunctionAttrs/nosync.ll

 ; RUN: opt -functionattrs -S < %s | FileCheck %s --check-prefix=FNATTR
-; RUN: opt -attributor -attributor-disable=false -attributor-max-iterations=4 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
+; RUN: opt -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=4 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
 ; Test cases designed for the nosync function attribute.
 ; FIXME's are used to indicate problems and missing attributes.
 
 ; struct RT {
 ;   char A;
 ;   int B[10][20];

llvm/test/Transforms/FunctionAttrs/nounwind.ll

 ; RUN: opt < %s -functionattrs -S | FileCheck %s
-; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations=9 -S | FileCheck %s --check-prefix=ATTRIBUTOR
+; RUN: opt < %s -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=12 -S | FileCheck %s --check-prefix=ATTRIBUTOR
 
 ; TEST 1
 ; CHECK: Function Attrs: norecurse nounwind readnone
 ; CHECK-NEXT: define i32 @foo1()
 ; ATTRIBUTOR: Function Attrs: nofree nosync nounwind
 ; ATTRIBUTOR-NEXT: define i32 @foo1()
 define i32 @foo1() {
   ret i32 1

llvm/test/Transforms/FunctionAttrs/read_write_returned_arguments_scc.ll

-; RUN: opt -functionattrs -enable-nonnull-arg-prop -attributor -attributor-disable=false -attributor-max-iterations=33 -S < %s | FileCheck %s
+; RUN: opt -functionattrs -enable-nonnull-arg-prop -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=28 -S < %s | FileCheck %s
 ;
 ; This is an evolved example to stress test SCC parameter attribute propagation.
 ; The SCC in this test is made up of the following six function, three of which
 ; are internal and three externally visible:
 ;
 ; static int *internal_ret0_nw(int *n0, int *w0);
 ; static int *internal_ret1_rw(int *r0, int *w0);
 ; static int *internal_ret1_rrw(int *r0, int *r1, int *w0);

llvm/test/Transforms/FunctionAttrs/willreturn.ll

 ; RUN: opt -functionattrs -S < %s | FileCheck %s --check-prefix=FNATTR
-; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations=6 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
+; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=6 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
 
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
 ; Test cases specifically designed for the "willreturn" function attribute.
 ; We use FIXME's to indicate problems and missing attributes.