[llvm-commits] [llvm] r163678 - in /llvm/trunk: lib/CodeGen/StackColoring.cpp test/CodeGen/X86/StackColoring.ll

[Nadav Rotem]

On Sep 15, 2012, at 14:24, Nuno Lopes <nunoplopes at sapo.pt> wrote:

> Wait, doesn't this mean that you don't need the lifetime markers at all??
> If you remove the markers that you cannot prove that are ok, then it's equivalent to not having this information at all, and then use only the computed liveness intervals.
> 

We use the lifetime markers to calculate the liveness intervals and throw away the intervals which are found to be broken. We need the markers to calculate the intervals.


> Nuno
> 
> ----- Original Message -----
>> Author: nadav
>> Date: Tue Sep 11 23:57:37 2012
>> New Revision: 163678
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=163678&view=rev
>> Log:
>> Stack coloring: remove lifetime intervals which contain escaped allocas.
>> 
>> The input program may contain intructions which are not inside lifetime
>> markers. This can happen due to a bug in the compiler or due to a bug in
>> user code (for example, returning a reference to a local variable).
>> This commit adds checks that all of the instructions in the function and
>> invalidates lifetime ranges which do not contain all of the instructions.
>> 
>> 
>> Modified:
>>   llvm/trunk/lib/CodeGen/StackColoring.cpp
>>   llvm/trunk/test/CodeGen/X86/StackColoring.ll
>> 
>> Modified: llvm/trunk/lib/CodeGen/StackColoring.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/StackColoring.cpp?rev=163678&r1=163677&r2=163678&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/StackColoring.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/StackColoring.cpp Tue Sep 11 23:57:37 2012
>> @@ -158,6 +158,14 @@
>>  /// slots to use the joint slots.
>>  void remapInstructions(DenseMap<int, int> &SlotRemap);
>> 
>> +  /// The input program may contain intructions which are not inside lifetime
>> +  /// markers. This can happen due to a bug in the compiler or due to a bug in
>> +  /// user code (for example, returning a reference to a local variable).
>> +  /// This procedure checks all of the instructions in the function and
>> +  /// invalidates lifetime ranges which do not contain all of the instructions
>> +  /// which access that frame slot.
>> +  void removeInvalidSlotRanges();
>> +
>>  /// Map entries which point to other entries to their destination.
>>  ///   A->B->C becomes A->C.
>>   void expungeSlotMap(DenseMap<int, int> &SlotRemap, unsigned NumSlots);
>> @@ -543,6 +551,43 @@
>>  DEBUG(dbgs()<<"Fixed "<<FixedInstr<<" machine instructions.\n");
>> }
>> 
>> +void StackColoring::removeInvalidSlotRanges() {
>> +  MachineFunction::iterator BB, BBE;
>> +  MachineBasicBlock::iterator I, IE;
>> +  for (BB = MF->begin(), BBE = MF->end(); BB != BBE; ++BB)
>> +    for (I = BB->begin(), IE = BB->end(); I != IE; ++I) {
>> +
>> +      if (I->getOpcode() == TargetOpcode::LIFETIME_START ||
>> +          I->getOpcode() == TargetOpcode::LIFETIME_END || I->isDebugValue())
>> +        continue;
>> +
>> +      // Check all of the machine operands.
>> +      for (unsigned i = 0 ; i <  I->getNumOperands(); ++i) {
>> +        MachineOperand &MO = I->getOperand(i);
>> +
>> +        if (!MO.isFI())
>> +          continue;
>> +
>> +        int Slot = MO.getIndex();
>> +
>> +        if (Slot<0)
>> +          continue;
>> +
>> +        if (Intervals[Slot]->empty())
>> +          continue;
>> +
>> +        // Check that the used slot is inside the calculated lifetime range.
>> +        // If it is not, warn about it and invalidate the range.
>> +        LiveInterval *Interval = Intervals[Slot];
>> +        SlotIndex Index = Indexes->getInstructionIndex(I);
>> +        if (Interval->find(Index) == Interval->end()) {
>> +          Intervals[Slot]->clear();
>> +          DEBUG(dbgs()<<"Invalidating range #"<<Slot<<"\n");
>> +        }
>> +      }
>> +    }
>> +}
>> +
>> void StackColoring::expungeSlotMap(DenseMap<int, int> &SlotRemap,
>>                                   unsigned NumSlots) {
>>  // Expunge slot remap map.
>> @@ -617,6 +662,8 @@
>>  // Propagate the liveness information.
>>  calculateLiveIntervals(NumSlots);
>> 
>> +  removeInvalidSlotRanges();
>> +
>>  // Maps old slots to new slots.
>>  DenseMap<int, int> SlotRemap;
>>  unsigned RemovedSlots = 0;
>> 
>> Modified: llvm/trunk/test/CodeGen/X86/StackColoring.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/StackColoring.ll?rev=163678&r1=163677&r2=163678&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/StackColoring.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/StackColoring.ll Tue Sep 11 23:57:37 2012
>> @@ -7,7 +7,6 @@
>> ;YESCOLOR: subq  $136, %rsp
>> ;NOCOLOR: subq  $264, %rsp
>> 
>> -
>> define i32 @myCall_w2(i32 %in) {
>> entry:
>>  %a = alloca [17 x i8*], align 8
>> @@ -328,7 +327,6 @@
>> 
>> ;YESCOLOR: subq  $272, %rsp
>> ;NOCOLOR: subq  $272, %rsp
>> -
>> define i32 @myCall_end_before_begin(i32 %in, i1 %d) {
>> entry:
>>  %a = alloca [17 x i8*], align 8
>> @@ -352,11 +350,37 @@
>>  ret i32 0
>> }
>> 
>> +; Check that we don't assert and crash even when there are allocas
>> +; outside the declared lifetime regions.
>> +;YESCOLOR: bad_range
>> +;NOCOLOR:  bad_range
>> +define void @bad_range() nounwind ssp {
>> +entry:
>> +  %A.i1 = alloca [100 x i32], align 4
>> +  %B.i2 = alloca [100 x i32], align 4
>> +  %A.i = alloca [100 x i32], align 4
>> +  %B.i = alloca [100 x i32], align 4
>> +  %0 = bitcast [100 x i32]* %A.i to i8*
>> +  call void @llvm.lifetime.start(i64 -1, i8* %0) nounwind
>> +  %1 = bitcast [100 x i32]* %B.i to i8*
>> +  call void @llvm.lifetime.start(i64 -1, i8* %1) nounwind
>> +  call void @bar([100 x i32]* %A.i, [100 x i32]* %B.i) nounwind
>> +  call void @llvm.lifetime.end(i64 -1, i8* %0) nounwind
>> +  call void @llvm.lifetime.end(i64 -1, i8* %1) nounwind
>> +  br label %block2
>> +
>> +block2:
>> +  ; I am used outside the marked lifetime.
>> +  call void @bar([100 x i32]* %A.i, [100 x i32]* %B.i) nounwind
>> +  ret void
>> +}
>> +
>> +
>> declare void @bar([100 x i32]* , [100 x i32]*) nounwind
>> 
>> declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind
>> 
>> declare void @llvm.lifetime.end(i64, i8* nocapture) nounwind
>> 
>> - declare i32 @foo(i32, i8*)
>> +declare i32 @foo(i32, i8*)