[llvm] r182485 - LoopVectorize: Make Value pointers that could be RAUW'ed a VH

Wed May 22 11:09:00 PDT 2013

Agreed. I applied it. :)

-bw

On May 22, 2013, at 10:09 AM, Rafael Espíndola <rafael.espindola at gmail.com> wrote:

> Hi Bill,
> 
> It would be really nice to pull this one to the 3.3 branch.
> 
> On 22 May 2013 12:54, Arnold Schwaighofer <aschwaighofer at apple.com> wrote:
>> Author: arnolds
>> Date: Wed May 22 11:54:56 2013
>> New Revision: 182485
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=182485&view=rev
>> Log:
>> LoopVectorize: Make Value pointers that could be RAUW'ed a VH
>> 
>> The Value pointers we store in the induction variable list can be RAUW'ed by a
>> call to SCEVExpander::expandCodeFor, use a TrackingVH instead. Do the same thing
>> in some other places where we store pointers that could potentially be RAUW'ed.
>> 
>> Fixes PR16073.
>> 
>> Added:
>>    llvm/trunk/test/Transforms/LoopVectorize/value-ptr-bug.ll
>> Modified:
>>    llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
>> 
>> Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp?rev=182485&r1=182484&r2=182485&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp Wed May 22 11:54:56 2013
>> @@ -80,6 +80,7 @@
>> #include "llvm/Support/Debug.h"
>> #include "llvm/Support/PatternMatch.h"
>> #include "llvm/Support/raw_ostream.h"
>> +#include "llvm/Support/ValueHandle.h"
>> #include "llvm/Target/TargetLibraryInfo.h"
>> #include "llvm/Transforms/Scalar.h"
>> #include "llvm/Transforms/Utils/BasicBlockUtils.h"
>> @@ -458,7 +459,7 @@ public:
>> 
>>     // The starting value of the reduction.
>>     // It does not have to be zero!
>> -    Value *StartValue;
>> +    TrackingVH<Value> StartValue;
>>     // The instruction who's value is used outside the loop.
>>     Instruction *LoopExitInstr;
>>     // The kind of the reduction.
>> @@ -503,7 +504,7 @@ public:
>>     /// This flag indicates if we need to add the runtime check.
>>     bool Need;
>>     /// Holds the pointers that we need to check.
>> -    SmallVector<Value*, 2> Pointers;
>> +    SmallVector<TrackingVH<Value>, 2> Pointers;
>>     /// Holds the pointer value at the beginning of the loop.
>>     SmallVector<const SCEV*, 2> Starts;
>>     /// Holds the pointer value at the end of the loop.
>> @@ -517,7 +518,7 @@ public:
>>     InductionInfo(Value *Start, InductionKind K) : StartValue(Start), IK(K) {}
>>     InductionInfo() : StartValue(0), IK(IK_NoInduction) {}
>>     /// Start value.
>> -    Value *StartValue;
>> +    TrackingVH<Value> StartValue;
>>     /// Induction kind.
>>     InductionKind IK;
>>   };
>> 
>> Added: llvm/trunk/test/Transforms/LoopVectorize/value-ptr-bug.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/value-ptr-bug.ll?rev=182485&view=auto
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/LoopVectorize/value-ptr-bug.ll (added)
>> +++ llvm/trunk/test/Transforms/LoopVectorize/value-ptr-bug.ll Wed May 22 11:54:56 2013
>> @@ -0,0 +1,50 @@
>> +; RUN: opt -S -loop-vectorize -force-vector-width=4 -force-vector-unroll=1 -dce -instcombine < %s | FileCheck %s
>> +
>> +target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
>> +
>> +; PR16073
>> +
>> +; Because we were caching value pointers accross a function call that could RAUW
>> +; we would generate an undefined value store below:
>> +; SCEVExpander::expandCodeFor would change a value (the start value of an
>> +; induction) that we cached in the induction variable list.
>> +
>> +; CHECK: test_vh
>> +; CHECK-NOT: store <4 x i8> undef
>> +
>> +define void @test_vh(i32* %ptr265, i32* %ptr266, i32 %sub267) {
>> +entry:
>> +  br label %loop
>> +
>> +loop:
>> +  %inc = phi i32 [ %sub267, %entry ], [ %add, %loop]
>> +  %ext.inc = sext i32 %inc to i64
>> +  %add.ptr265 = getelementptr inbounds i32* %ptr265, i64 %ext.inc
>> +  %add.ptr266 = getelementptr inbounds i32* %ptr266, i64 %ext.inc
>> +  %add = add i32 %inc, 9
>> +  %cmp = icmp slt i32 %add, 140
>> +  br i1 %cmp, label %block1, label %loop
>> +
>> +block1:
>> +  %sub267.lcssa = phi i32 [ %add, %loop ]
>> +  %add.ptr266.lcssa = phi i32* [ %add.ptr266, %loop ]
>> +  %add.ptr265.lcssa = phi i32* [ %add.ptr265, %loop ]
>> +  %tmp29 = bitcast i32* %add.ptr265.lcssa to i8*
>> +  %tmp30 = bitcast i32* %add.ptr266.lcssa to i8*
>> +  br label %do.body272
>> +
>> +do.body272:
>> +  %row_width.5 = phi i32 [ %sub267.lcssa, %block1 ], [ %dec, %do.body272 ]
>> +  %sp.4 = phi i8* [ %tmp30, %block1 ], [ %incdec.ptr273, %do.body272 ]
>> +  %dp.addr.4 = phi i8* [ %tmp29, %block1 ], [ %incdec.ptr274, %do.body272 ]
>> +  %incdec.ptr273 = getelementptr inbounds i8* %sp.4, i64 1
>> +  %tmp31 = load i8* %sp.4, align 1
>> +  %incdec.ptr274 = getelementptr inbounds i8* %dp.addr.4, i64 1
>> +  store i8 %tmp31, i8* %dp.addr.4, align 1
>> +  %dec = add i32 %row_width.5, -1
>> +  %cmp276 = icmp eq i32 %dec, 0
>> +  br i1 %cmp276, label %loop.exit, label %do.body272
>> +
>> +loop.exit:
>> +  ret void
>> +}
>> 
>> 
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