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Move relational-optimizing code to optimizeRelational [NFC] #5036

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Merged
kripken merged 1 commit into from
Sep 13, 2022
Merged

Move relational-optimizing code to optimizeRelational [NFC] #5036

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68 changes: 35 additions & 33 deletions src/passes/OptimizeInstructions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3570,36 +3570,6 @@ struct OptimizeInstructions
return left;
}
}
// x + C1 > C2 ==> x > (C2-C1) if no overflowing, C2 >= C1
// x + C1 > C2 ==> x + (C1-C2) > 0 if no overflowing, C2 < C1
// And similarly for other relational operations on integers.
if (curr->isRelational()) {
Binary* add;
Const* c1;
Const* c2;
if ((matches(curr,
binary(binary(&add, Add, any(), ival(&c1)), ival(&c2))) ||
matches(curr,
binary(binary(&add, Add, any(), ival(&c1)), ival(&c2)))) &&
!canOverflow(add)) {
if (c2->value.geU(c1->value).getInteger()) {
// This is the first line above, we turn into x > (C2-C1)
c2->value = c2->value.sub(c1->value);
curr->left = add->left;
return curr;
}
// This is the second line above, we turn into x + (C1-C2) > 0. Other
// optimizations can often kick in later. However, we must rule out the
// case where C2 is already 0 (as then we would not actually change
// anything, and we could infinite loop).
auto zero = Literal::makeZero(c2->type);
if (c2->value != zero) {
c1->value = c1->value.sub(c2->value);
c2->value = zero;
return curr;
}
}
}
{
// x != NaN ==> 1
// x <=> NaN ==> 0
Expand Down Expand Up @@ -3902,6 +3872,9 @@ struct OptimizeInstructions

// TODO: templatize on type?
Expression* optimizeRelational(Binary* curr) {
using namespace Abstract;
using namespace Match;

auto type = curr->right->type;
if (curr->left->type.isInteger()) {
if (curr->op == Abstract::getBinary(type, Abstract::Eq) ||
Expand Down Expand Up @@ -3935,9 +3908,6 @@ struct OptimizeInstructions
// unsigned(x - y) > 0 => x != y
// unsigned(x - y) <= 0 => x == y
{
using namespace Abstract;
using namespace Match;

Binary* inner;
// unsigned(x - y) > 0 => x != y
if (matches(curr,
Expand Down Expand Up @@ -3969,6 +3939,38 @@ struct OptimizeInstructions
}
}

// x + C1 > C2 ==> x > (C2-C1) if no overflowing, C2 >= C1
// x + C1 > C2 ==> x + (C1-C2) > 0 if no overflowing, C2 < C1
// And similarly for other relational operations on integers with a "+"
// on the left.
{
Binary* add;
Const* c1;
Const* c2;
if ((matches(curr,
binary(binary(&add, Add, any(), ival(&c1)), ival(&c2))) ||
matches(curr,
binary(binary(&add, Add, any(), ival(&c1)), ival(&c2)))) &&
!canOverflow(add)) {
if (c2->value.geU(c1->value).getInteger()) {
// This is the first line above, we turn into x > (C2-C1)
c2->value = c2->value.sub(c1->value);
curr->left = add->left;
return curr;
}
// This is the second line above, we turn into x + (C1-C2) > 0. Other
// optimizations can often kick in later. However, we must rule out
// the case where C2 is already 0 (as then we would not actually
// change anything, and we could infinite loop).
auto zero = Literal::makeZero(c2->type);
if (c2->value != zero) {
c1->value = c1->value.sub(c2->value);
c2->value = zero;
return curr;
}
}
}

// Comparisons can sometimes be simplified depending on the number of
// bits, e.g. (unsigned)x > y must be true if x has strictly more bits.
// A common case is a constant on the right, e.g. (x & 255) < 256 must be
Expand Down