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Gtneg mul divoptimizations #45604

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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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55 changes: 54 additions & 1 deletion src/coreclr/src/jit/morph.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -11843,7 +11843,22 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac)
case GT_CAST:
return fgMorphCast(tree);

case GT_MUL:
case GT_MUL:
// -a * C => a * -C, where C is constant
// MUL(NEG(a), C) => MUL(a, NEG(C))
if (op1->OperIs(GT_NEG) && !op1->IsCnsIntOrI() && op2->IsCnsIntOrI())
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!op1->IsCnsIntOrI() - I think you meant op1->gtOp1()->IsCnsIntOrI() here.

{
// tree: MUL
// op1: a
// op2: NEG
// op2Child: C
op1 = op1->AsOp()->gtOp1; // a
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I'd rewrite to be:

    tree->AsOp()->gtOp1 = op1->gtGetOp1();
    DEBUG_DESTROY_NODE(op1);
    op2->AsIntCon()->SetIconValue(-op2->AsIntCon()->IconValue());
    return tree;

op2->AsIntCon()->SetIconValue(-op2->AsIntCon()->IconValue()); // -C

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

#ifndef TARGET_64BIT
if (typ == TYP_LONG)
Expand Down Expand Up @@ -11991,6 +12006,22 @@ 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 (op1->OperIs(GT_NEG) && !op1->IsCnsIntOrI() && op2->IsCnsIntOrI())
{
// tree: DIV
// op1: a
// op2: NEG
// op2Child: C
op1 = op1->AsOp()->gtOp1; // a
op2->AsIntCon()->SetIconValue(-op2->AsIntCon()->IconValue()); // -C

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

#ifndef TARGET_64BIT
if (typ == TYP_LONG)
{
Expand All @@ -12011,6 +12042,7 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac)
{
op2 = gtFoldExprConst(op2);
}

break;

case GT_UDIV:
Expand Down Expand Up @@ -13367,6 +13399,7 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac)

case GT_MUL:


#ifndef TARGET_64BIT
if (typ == TYP_LONG)
{
Expand Down Expand Up @@ -13855,6 +13888,26 @@ 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