Skip to content

Commit

Permalink
Allow gtFoldExprSpecial to handle side effects
Browse files Browse the repository at this point in the history
  • Loading branch information
@tannergooding
tannergooding committed Jun 13, 2024
1 parent 2a0162b commit 960870a
Showing 1 changed file with 53 additions and 38 deletions.
91 changes: 53 additions & 38 deletions src/coreclr/jit/gentree.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14322,15 +14322,12 @@ GenTree* Compiler::gtFoldExprSpecial(GenTree* tree)

val = cons->AsIntConCommon()->IconValue();

// Transforms that would drop op cannot be performed if op has side effects
bool opHasSideEffects = (op->gtFlags & GTF_SIDE_EFFECT) != 0;

// Helper function that creates a new IntCon node and morphs it, if required
auto NewMorphedIntConNode = [&](int value) -> GenTreeIntCon* {
GenTreeIntCon* icon = gtNewIconNode(value);
if (fgGlobalMorph)
{
fgMorphTreeDone(icon);
INDEBUG(icon->gtDebugFlags |= GTF_DEBUG_NODE_MORPHED);
}
return icon;
};
Expand Down Expand Up @@ -14365,43 +14362,52 @@ GenTree* Compiler::gtFoldExprSpecial(GenTree* tree)
switch (oper)
{
case GT_LE:
if (tree->IsUnsigned() && (val == 0) && (op1 == cons) && !opHasSideEffects)
{
if (tree->IsUnsigned() && (val == 0) && (op1 == cons))
{
// unsigned (0 <= x) is always true
op = NewMorphedIntConNode(1);
op = gtWrapWithSideEffects(NewMorphedIntConNode(1), op, GTF_ALL_EFFECT);
goto DONE_FOLD;
}
break;
}

case GT_GE:
if (tree->IsUnsigned() && (val == 0) && (op2 == cons) && !opHasSideEffects)
{
if (tree->IsUnsigned() && (val == 0) && (op2 == cons))
{
// unsigned (x >= 0) is always true
op = NewMorphedIntConNode(1);
op = gtWrapWithSideEffects(NewMorphedIntConNode(1), op, GTF_ALL_EFFECT);
goto DONE_FOLD;
}
break;
}

case GT_LT:
if (tree->IsUnsigned() && (val == 0) && (op2 == cons) && !opHasSideEffects)
{
if (tree->IsUnsigned() && (val == 0) && (op2 == cons))
{
// unsigned (x < 0) is always false
op = NewMorphedIntConNode(0);
op = gtWrapWithSideEffects(NewMorphedIntConNode(0), op, GTF_ALL_EFFECT);
goto DONE_FOLD;
}
break;
}

case GT_GT:
if (tree->IsUnsigned() && (val == 0) && (op1 == cons) && !opHasSideEffects)
{
if (tree->IsUnsigned() && (val == 0) && (op1 == cons))
{
// unsigned (0 > x) is always false
op = NewMorphedIntConNode(0);
op = gtWrapWithSideEffects(NewMorphedIntConNode(0), op, GTF_ALL_EFFECT);
goto DONE_FOLD;
}
}
FALLTHROUGH;

case GT_EQ:
case GT_NE:

{
// Optimize boxed value classes; these are always false. This IL is
// generated when a generic value is tested against null:
// <T> ... foo(T x) { ... if ((object)x == null) ...
Expand Down Expand Up @@ -14463,57 +14469,59 @@ GenTree* Compiler::gtFoldExprSpecial(GenTree* tree)
{
return gtFoldBoxNullable(tree);
}

break;
}

case GT_ADD:
{
if (val == 0)
{
goto DONE_FOLD;
}
break;
}

case GT_MUL:
{
if (val == 1)
{
goto DONE_FOLD;
}
else if (val == 0)
{
/* Multiply by zero - return the 'zero' node, but not if side effects */
if (!opHasSideEffects)
{
op = cons;
goto DONE_FOLD;
}
// Multiply by zero - return the 'zero' node
op = gtWrapWithSideEffects(cons, op, GTF_ALL_EFFECT);
goto DONE_FOLD;
}
break;
}

case GT_DIV:
case GT_UDIV:
{
if ((op2 == cons) && (val == 1) && !op1->OperIsConst())
{
goto DONE_FOLD;
}
break;
}

case GT_SUB:
{
if ((op2 == cons) && (val == 0) && !op1->OperIsConst())
{
goto DONE_FOLD;
}
break;
}

case GT_AND:
{
if (val == 0)
{
/* AND with zero - return the 'zero' node, but not if side effects */

if (!opHasSideEffects)
{
op = cons;
goto DONE_FOLD;
}
// AND with zero - return the 'zero' node
op = gtWrapWithSideEffects(cons, op, GTF_ALL_EFFECT);
goto DONE_FOLD;
}
else if (val == 0xFF)
{
Expand Down Expand Up @@ -14546,8 +14554,10 @@ GenTree* Compiler::gtFoldExprSpecial(GenTree* tree)
}
}
break;
}

case GT_OR:
{
if (val == 0)
{
goto DONE_FOLD;
Expand All @@ -14558,34 +14568,33 @@ GenTree* Compiler::gtFoldExprSpecial(GenTree* tree)

assert(val == 1);

/* OR with one - return the 'one' node, but not if side effects */

if (!opHasSideEffects)
{
op = cons;
goto DONE_FOLD;
}
// OR with one - return the 'one' node
op = gtWrapWithSideEffects(cons, op, GTF_ALL_EFFECT);
goto DONE_FOLD;
}
break;
}

case GT_LSH:
case GT_RSH:
case GT_RSZ:
case GT_ROL:
case GT_ROR:
{
if (val == 0)
{
if (op2 == cons)
{
goto DONE_FOLD;
}
else if (!opHasSideEffects)
else
{
op = cons;
op = gtWrapWithSideEffects(cons, op, GTF_ALL_EFFECT);
goto DONE_FOLD;
}
}
break;
}

case GT_QMARK:
{
Expand All @@ -14608,9 +14617,8 @@ GenTree* Compiler::gtFoldExprSpecial(GenTree* tree)
{
fgWalkTreePre(&op, gtClearColonCond);
}
}

goto DONE_FOLD;
}

default:
break;
Expand All @@ -14627,6 +14635,13 @@ GenTree* Compiler::gtFoldExprSpecial(GenTree* tree)
JITDUMP("Transformed into:\n");
DISPTREE(op);

if (fgGlobalMorph)
{
// We can sometimes produce a comma over the constant if the original op
// had a side effect, so just ensure we set the flag (which will be already
// set for the operands otherwise).
INDEBUG(op->gtDebugFlags |= GTF_DEBUG_NODE_MORPHED);
}
return op;
}

Expand Down

0 comments on commit 960870a

Please sign in to comment.