[llvm] r228760 - EarlyCSE: It isn't safe to CSE across synchronization boundaries

[Hans Wennborg]

Merged in r228790.

Thanks,
Hans

On Tue, Feb 10, 2015 at 6:08 PM, David Majnemer
<david.majnemer at gmail.com> wrote:
> Hi Hans,
>
> I think r228760 and r228761 should get merged into 3.6
>
> On Tue, Feb 10, 2015 at 3:09 PM, David Majnemer <david.majnemer at gmail.com>
> wrote:
>>
>> Author: majnemer
>> Date: Tue Feb 10 17:09:43 2015
>> New Revision: 228760
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=228760&view=rev
>> Log:
>> EarlyCSE: It isn't safe to CSE across synchronization boundaries
>>
>> This fixes PR22514.
>>
>> Modified:
>>     llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp
>>     llvm/trunk/test/Transforms/EarlyCSE/basic.ll
>>
>> Modified: llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp?rev=228760&r1=228759&r2=228760&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp Tue Feb 10 17:09:43 2015
>> @@ -527,6 +527,9 @@ bool EarlyCSE::processNode(DomTreeNode *
>>        // Ignore volatile loads.
>>        if (MemInst.isVolatile()) {
>>          LastStore = nullptr;
>> +        // Don't CSE across synchronization boundaries.
>> +        if (Inst->mayWriteToMemory())
>> +          ++CurrentGeneration;
>>          continue;
>>        }
>>
>>
>> Modified: llvm/trunk/test/Transforms/EarlyCSE/basic.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/EarlyCSE/basic.ll?rev=228760&r1=228759&r2=228760&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/EarlyCSE/basic.ll (original)
>> +++ llvm/trunk/test/Transforms/EarlyCSE/basic.ll Tue Feb 10 17:09:43 2015
>> @@ -193,4 +193,10 @@ define void @test11(i32 *%P) {
>>    ; CHECK-NEXT: ret void
>>  }
>>
>> -
>> +define i32 @test12(i1 %B, i32* %P1, i32* %P2) {
>> +  %load0 = load i32* %P1
>> +  %1 = load atomic i32* %P2 seq_cst, align 4
>> +  %load1 = load i32* %P1
>> +  %sel = select i1 %B, i32 %load0, i32 %load1
>> +  ret i32 %sel
>> +}
>>
>>
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>
>