[llvm-commits] [llvm] r48491 - in /llvm/trunk: lib/CodeGen/SelectionDAG/DAGCombiner.cpp test/CodeGen/X86/field-extract-use-trunc.ll
Evan Cheng
evan.cheng at apple.com
Wed Mar 19 10:59:42 PDT 2008
Let's leave them both as free for now. Thanks.
Evan
On Mar 19, 2008, at 10:01 AM, Christopher Lamb wrote:
> There are two versions of isTruncateFree, one that takes Types, and
> one that takes ValueTypes. Should i1 truncates be free in the Type
> version but not so in the ValueType version?
>
> --
> Chris
>
> On Mar 19, 2008, at 1:46 AM, Evan Cheng wrote:
>
>> Well... Actually it should return true. MVT::i1 is promoted to
>> MVT::i8 so on x86 it really should be free.
>>
>> Evan
>>
>> On Mar 19, 2008, at 1:28 AM, Christopher Lamb wrote:
>>
>>> Well, I'm not seeing that pessimization anymore. strange.
>>>
>>> On Mar 19, 2008, at 1:17 AM, Christopher Lamb wrote:
>>>
>>>> Fixing isTruncateFree for MVT::i1 seems to reduce code quality,
>>>> it causes some extra mov's to pop up in the dg tests. =(
>>>>
>>>> On Mar 19, 2008, at 1:01 AM, Evan Cheng wrote:
>>>>
>>>>> No, it's not. Please fix. But that's a profitability issue, it
>>>>> shouldn't cause miscompilation?
>>>>>
>>>>> Evan
>>>>>
>>>>> On Mar 19, 2008, at 12:54 AM, Christopher Lamb wrote:
>>>>>
>>>>>> X86 TargetLowering claims that truncate from any integer type
>>>>>> to MVT::i1 is free. Is this correct?
>>>>>>
>>>>>> --
>>>>>> Chris
>>>>>>
>>>>>> On Mar 18, 2008, at 3:23 PM, Bill Wendling wrote:
>>>>>>
>>>>>>> Hi Christopher,
>>>>>>>
>>>>>>> The attached testcase fails with this patch. I'm reverting it
>>>>>>> temporarily.
>>>>>>>
>>>>>>> -bw
>>>>>>>
>>>>>>> On Tue, Mar 18, 2008 at 9:46 AM, Christopher Lamb
>>>>>>> <christopher.lamb at gmail.com> wrote:
>>>>>>>> Author: clamb
>>>>>>>> Date: Tue Mar 18 11:46:39 2008
>>>>>>>> New Revision: 48491
>>>>>>>>
>>>>>>>> URL: http://llvm.org/viewvc/llvm-project?rev=48491&view=rev
>>>>>>>> Log:
>>>>>>>> Target independent DAG transform to use truncate for field
>>>>>>>> extraction + sign extend on targets where this is profitable.
>>>>>>>> Passes nightly on x86-64.
>>>>>>>>
>>>>>>>> Added:
>>>>>>>> llvm/trunk/test/CodeGen/X86/field-extract-use-trunc.ll
>>>>>>>> Modified:
>>>>>>>> llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
>>>>>>>>
>>>>>>>> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
>>>>>>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=48491&r1=48490&r2=48491&view=diff
>>>>>>>>
>>>>>>>>
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> ===============================================================
>>>>>>>> --- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
>>>>>>>> (original)
>>>>>>>> +++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Tue
>>>>>>>> Mar 18 11:46:39 2008
>>>>>>>> @@ -2374,6 +2374,32 @@
>>>>>>>> DAG.getValueType(EVT));
>>>>>>>> }
>>>>>>>>
>>>>>>>> + // fold sra (shl X, m), result_size - n
>>>>>>>> + // -> (sign_extend (trunc (shl X, result_size - n - m)))
>>>>>>>> for
>>>>>>>> + // result_size - n != m. If truncate is free for the
>>>>>>>> target sext(shl) is
>>>>>>>> + // likely to result in better code.
>>>>>>>> + if (N0.getOpcode() == ISD::SHL) {
>>>>>>>> + // Get the two constanst of the shifts, CN0 = m, CN = n.
>>>>>>>> + const ConstantSDNode *N01C =
>>>>>>>> dyn_cast<ConstantSDNode>(N0.getOperand(1));
>>>>>>>> + if (N01C && N1C) {
>>>>>>>> + // Determine if the truncate type's bitsize would
>>>>>>>> correspond to
>>>>>>>> + // an integer type for this target.
>>>>>>>> + unsigned VTValSize = MVT::getSizeInBits(VT);
>>>>>>>> + MVT::ValueType TruncVT =
>>>>>>>> MVT::getIntegerType(VTValSize - N1C->getValue());
>>>>>>>> + unsigned ShiftAmt = N1C->getValue() - N01C->getValue();
>>>>>>>> +
>>>>>>>> + // If the shift wouldn't be a noop, the truncated
>>>>>>>> type is an actual type,
>>>>>>>> + // and the truncate is free, then proceed with the
>>>>>>>> transform.
>>>>>>>> + if (ShiftAmt != 0 &&
>>>>>>>> + !MVT::isExtendedVT(TruncVT) &&
>>>>>>>> TLI.isTruncateFree(VT, TruncVT)) {
>>>>>>>> + SDOperand Amt = DAG.getConstant(ShiftAmt,
>>>>>>>> TLI.getShiftAmountTy());
>>>>>>>> + SDOperand Shift = DAG.getNode(ISD::SRL, VT,
>>>>>>>> N0.getOperand(0), Amt);
>>>>>>>> + SDOperand Trunc = DAG.getNode(ISD::TRUNCATE,
>>>>>>>> TruncVT, Shift);
>>>>>>>> + return DAG.getNode(ISD::SIGN_EXTEND, N-
>>>>>>>> >getValueType(0), Trunc);
>>>>>>>> + }
>>>>>>>> + }
>>>>>>>> + }
>>>>>>>> +
>>>>>>>> // fold (sra (sra x, c1), c2) -> (sra x, c1+c2)
>>>>>>>> if (N1C && N0.getOpcode() == ISD::SRA) {
>>>>>>>> if (ConstantSDNode *C1 =
>>>>>>>> dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
>>>>>>>>
>>>>>>>> Added: llvm/trunk/test/CodeGen/X86/field-extract-use-trunc.ll
>>>>>>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/field-extract-use-trunc.ll?rev=48491&view=auto
>>>>>>>>
>>>>>>>>
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> =
>>>>>>>> ===============================================================
>>>>>>>> --- llvm/trunk/test/CodeGen/X86/field-extract-use-trunc.ll
>>>>>>>> (added)
>>>>>>>> +++ llvm/trunk/test/CodeGen/X86/field-extract-use-trunc.ll
>>>>>>>> Tue Mar 18 11:46:39 2008
>>>>>>>> @@ -0,0 +1,39 @@
>>>>>>>> +; RUN: llvm-as < %s | llc -march=x86 | grep sar | count 1
>>>>>>>> +; RUN: llvm-as < %s | llc -march=x86-64 | not grep sar
>>>>>>>> +
>>>>>>>> +define i32 @test(i32 %f12) {
>>>>>>>> + %tmp7.25 = lshr i32 %f12, 16
>>>>>>>> + %tmp7.26 = trunc i32 %tmp7.25 to i8
>>>>>>>> + %tmp78.2 = sext i8 %tmp7.26 to i32
>>>>>>>> + ret i32 %tmp78.2
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +define i32 @test2(i32 %f12) {
>>>>>>>> + %f11 = shl i32 %f12, 8
>>>>>>>> + %tmp7.25 = ashr i32 %f11, 24
>>>>>>>> + ret i32 %tmp7.25
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +define i32 @test3(i32 %f12) {
>>>>>>>> + %f11 = shl i32 %f12, 13
>>>>>>>> + %tmp7.25 = ashr i32 %f11, 24
>>>>>>>> + ret i32 %tmp7.25
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +define i64 @test4(i64 %f12) {
>>>>>>>> + %f11 = shl i64 %f12, 32
>>>>>>>> + %tmp7.25 = ashr i64 %f11, 32
>>>>>>>> + ret i64 %tmp7.25
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +define i16 @test5(i16 %f12) {
>>>>>>>> + %f11 = shl i16 %f12, 2
>>>>>>>> + %tmp7.25 = ashr i16 %f11, 8
>>>>>>>> + ret i16 %tmp7.25
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +define i16 @test6(i16 %f12) {
>>>>>>>> + %f11 = shl i16 %f12, 8
>>>>>>>> + %tmp7.25 = ashr i16 %f11, 8
>>>>>>>> + ret i16 %tmp7.25
>>>>>>>> +}
>>>>>>>> \ No newline at end of file
>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
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>>>>>>>>
>>>>>>>> <bugpoint-reduced-simplified.bc>
>>>>>>> _______________________________________________
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>>>>>>
>>>>>> --
>>>>>> Christopher Lamb
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> llvm-commits mailing list
>>>>>> llvm-commits at cs.uiuc.edu
>>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>>>>
>>>>> _______________________________________________
>>>>> llvm-commits mailing list
>>>>> llvm-commits at cs.uiuc.edu
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>>>>
>>>> --
>>>> Christopher Lamb
>>>>
>>>>
>>>>
>>>
>>> --
>>> Christopher Lamb
>>>
>>>
>>>
>>> _______________________________________________
>>> llvm-commits mailing list
>>> llvm-commits at cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>
>
> --
> Christopher Lamb
>
>
>
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