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Gtneg mul divoptimizations #45604

Merged
merged 19 commits into from
Jan 12, 2021
Merged

Gtneg mul divoptimizations #45604

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e487fe3
GT_NEG optimization for multiplication and division
alexcovington Dec 3, 2020
7f04f55
Distribute negation over parenthetical multiplication or division.
alexcovington Dec 3, 2020
bbaf21f
Removing duplicate logic that I had put in accidently.
alexcovington Dec 4, 2020
bc91dcc
Check overflow and other conditions before performing morph
alexcovington Dec 7, 2020
084a285
Merging change that removes src/coreclr/src directory
alexcovington Dec 9, 2020
b575ab6
Merge branch 'master' of https://github.com/dotnet/runtime into gtneg…
alexcovington Dec 14, 2020
9727f8e
Resolved merge conflict and cleanup morph.cpp
alexcovington Dec 14, 2020
7829712
Resolved merge conflict
alexcovington Dec 28, 2020
b4bf7e9
Formatting morph.cpp
alexcovington Dec 29, 2020
bd9a464
Returning tree after performing smpop again to fix flags
alexcovington Jan 6, 2021
9136999
Formatting
alexcovington Jan 6, 2021
2e72f94
Added check for optimizations, formatting.
alexcovington Jan 7, 2021
6467520
Using gtIsActiveCSE_Candidate instead of fgGlobalMorph
alexcovington Jan 7, 2021
4a7f9b5
Update src/coreclr/jit/morph.cpp
alexcovington Jan 7, 2021
cb71a90
Formatting
alexcovington Jan 7, 2021
fea92de
delete formatting changes.
Jan 8, 2021
8d2dc8e
Add a test.
Jan 11, 2021
46b8fff
Change the conditions a bit.
Jan 11, 2021
55d54e6
Better names for the tests.
Jan 11, 2021
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102 changes: 78 additions & 24 deletions src/coreclr/jit/morph.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2833,8 +2833,8 @@ void Compiler::fgInitArgInfo(GenTreeCall* call)
{
noway_assert(call->gtCallArgs->GetNode()->TypeGet() == TYP_I_IMPL ||
call->gtCallArgs->GetNode()->TypeGet() == TYP_BYREF ||
call->gtCallArgs->GetNode()->gtOper ==
GT_NOP); // the arg was already morphed to a register (fgMorph called twice)
call->gtCallArgs->GetNode()->gtOper == GT_NOP); // the arg was already morphed to a register
// (fgMorph called twice)
maxRegArgs = 1;
}
else
Expand Down Expand Up @@ -9090,8 +9090,8 @@ GenTree* Compiler::fgMorphCall(GenTreeCall* call)
// copy-back).
unsigned retValTmpNum = BAD_VAR_NUM;
CORINFO_CLASS_HANDLE structHnd = nullptr;
if (call->HasRetBufArg() &&
call->gtCallLateArgs == nullptr) // Don't do this if we're re-morphing (which will make late args non-null).
if (call->HasRetBufArg() && call->gtCallLateArgs == nullptr) // Don't do this if we're re-morphing (which will make
// late args non-null).
{
// We're enforcing the invariant that return buffers pointers (at least for
// struct return types containing GC pointers) are never pointers into the heap.
Expand Down Expand Up @@ -11605,16 +11605,16 @@ GenTree* Compiler::getSIMDStructFromField(GenTree* tree,
}

/*****************************************************************************
* If a read operation tries to access simd struct field, then transform the
* operation to the SIMD intrinsic SIMDIntrinsicGetItem, and return the new tree.
* Otherwise, return the old tree.
* Argument:
* tree - GenTree*. If this pointer points to simd struct which is used for simd
* intrinsic, we will morph it as simd intrinsic SIMDIntrinsicGetItem.
* Return:
* A GenTree* which points to the new tree. If the tree is not for simd intrinsic,
* return nullptr.
*/
* If a read operation tries to access simd struct field, then transform the
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did jit-format cause these changes or were these unintentional edits? Could you please try to delete them and run jit-format again?

* operation to the SIMD intrinsic SIMDIntrinsicGetItem, and return the new tree.
* Otherwise, return the old tree.
* Argument:
* tree - GenTree*. If this pointer points to simd struct which is used for simd
* intrinsic, we will morph it as simd intrinsic SIMDIntrinsicGetItem.
* Return:
* A GenTree* which points to the new tree. If the tree is not for simd intrinsic,
* return nullptr.
*/

GenTree* Compiler::fgMorphFieldToSIMDIntrinsicGet(GenTree* tree)
{
Expand All @@ -11635,16 +11635,16 @@ GenTree* Compiler::fgMorphFieldToSIMDIntrinsicGet(GenTree* tree)
}

/*****************************************************************************
* Transform an assignment of a SIMD struct field to SIMD intrinsic
* SIMDIntrinsicSet*, and return a new tree. If it is not such an assignment,
* then return the old tree.
* Argument:
* tree - GenTree*. If this pointer points to simd struct which is used for simd
* intrinsic, we will morph it as simd intrinsic set.
* Return:
* A GenTree* which points to the new tree. If the tree is not for simd intrinsic,
* return nullptr.
*/
* Transform an assignment of a SIMD struct field to SIMD intrinsic
* SIMDIntrinsicSet*, and return a new tree. If it is not such an assignment,
* then return the old tree.
* Argument:
* tree - GenTree*. If this pointer points to simd struct which is used for simd
* intrinsic, we will morph it as simd intrinsic set.
* Return:
* A GenTree* which points to the new tree. If the tree is not for simd intrinsic,
* return nullptr.
*/

GenTree* Compiler::fgMorphFieldAssignToSIMDIntrinsicSet(GenTree* tree)
{
Expand Down Expand Up @@ -11909,6 +11909,22 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac)
return fgMorphCast(tree);

case GT_MUL:
// -a * C => a * -C, where C is constant
// MUL(NEG(a), C) => MUL(a, NEG(C))
if (fgGlobalMorph && op1->OperIs(GT_NEG) && !op1->gtGetOp1()->IsCnsIntOrI() && op2->IsCnsIntOrI() &&
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opts.OptimizationEnabled() check is missed here and in the other cases, when this flag is set to false we don't want to do any CQ transformations, only what is needed for correctness, it is used, for example, in minopts.

!op2->IsIconHandle() && op2->AsIntCon()->IconValue() != 1 && op2->AsIntCon()->IconValue() != 0 &&
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Why do you check fgGlobalMorph here? Did you want to use !gtIsActiveCSE_Candidate ? gtIsActiveCSE_Candidate means it is not CSE phase (it could be a global morph phase instead) or this tree is not the current candidate that could be dangerous to remove.

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I checked fgGlobalMorph because it was checked in #43921, which is what I based most of this work on. I can use !gtIsActiveCSE_Candidate if that would be better.

Still learning about the CoreCLR JIT, I greatly appreciate the advice :).

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On second thought I think fgGlobalMorph check is fine here because you are changing node value without updating its VN.
An alternative could be to do the optimization with !gtIsActiveCSE_Candidate but create a new tree for the constant:

tree->AsOp()->gtOp2 = gtNewIconNode(-op2->AsIntCon()->IconValue(), op2->TypeGet());
DEBUG_DESTROY_NODE(op2);

it would allow the optimization to happen in other phases, so I think it would be better.

op2->AsIntCon()->IconValue() != -1 && !tree->gtOverflow())
{
// tree: MUL
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is this the comment for the tree before the transformation?
then it should be

// tree: MUL
// op1: Neg
// op1Child: a
// op2: Const

// op1: a
// op2: NEG
// op2Child: C

tree->AsOp()->gtOp1 = op1->gtGetOp1();
DEBUG_DESTROY_NODE(op1);
op2->AsIntCon()->SetIconValue(-op2->AsIntCon()->IconValue()); // -C
return fgMorphSmpOp(tree, mac);
}

#ifndef TARGET_64BIT
if (typ == TYP_LONG)
Expand Down Expand Up @@ -12056,6 +12072,23 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac)
return fgMorphSmpOp(tree, mac);
}

// -a / C => a / -C, where C is constant
// DIV(NEG(a), C) => DIV(a, NEG(C))
if (fgGlobalMorph && op1->OperIs(GT_NEG) && !op1->gtGetOp1()->IsCnsIntOrI() && op2->IsCnsIntOrI() &&
!op2->IsIconHandle() && op2->AsIntCon()->IconValue() != 1 && op2->AsIntCon()->IconValue() != 0 &&
op2->AsIntCon()->IconValue() != -1)
{
// tree: DIV
// op1: a
// op2: NEG
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the same here.

// op2Child: C

tree->AsOp()->gtOp1 = op1->gtGetOp1();
DEBUG_DESTROY_NODE(op1);
op2->AsIntCon()->SetIconValue(-op2->AsIntCon()->IconValue()); // -C
return fgMorphSmpOp(tree, mac);
}

#ifndef TARGET_64BIT
if (typ == TYP_LONG)
{
Expand Down Expand Up @@ -13920,6 +13953,27 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac)
return child;
}

// Distribute negation over simple multiplication/division expressions
if (op1->OperIs(GT_MUL) || op1->OperIs(GT_DIV))
{
if (!op1->AsOp()->gtOp1->IsCnsIntOrI() && op1->AsOp()->gtOp2->IsCnsIntOrI())
{
// -(a * C) => a * -C
// -(a / C) => a / -C
oper = op1->gtOper;
tree->SetOper(op1->gtOper);
GenTree* newOp1 = op1->AsOp()->gtOp1; // a
GenTree* newOp2 = op1->AsOp()->gtOp2; // C
newOp2->AsIntCon()->SetIconValue(-newOp2->AsIntCon()->IconValue());

// Only need to destroy op1 since op2 will be null already
DEBUG_DESTROY_NODE(op1);

tree->AsOp()->gtOp1 = op1 = newOp1;
tree->AsOp()->gtOp2 = op2 = newOp2;
}
}

/* Any constant cases should have been folded earlier */
noway_assert(!op1->OperIsConst() || !opts.OptEnabled(CLFLG_CONSTANTFOLD) || optValnumCSE_phase);
break;
Expand Down