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Fix inconsistent min()/max() tie-breaking on signed zero via the frameless 2-arg fast path #23505

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Fix inconsistent min()/max() tie-breaking on signed zero via the frameless 2-arg fast path #23505

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8 changes: 4 additions & 4 deletions ext/standard/array.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1211,7 +1211,7 @@ ZEND_FRAMELESS_FUNCTION(min, 2)
zend_long lhs_lval = Z_LVAL_P(lhs);

if (EXPECTED(Z_TYPE_P(rhs) == IS_LONG)) {
RETURN_COPY_VALUE(lhs_lval < Z_LVAL_P(rhs) ? lhs : rhs);
RETURN_COPY_VALUE(lhs_lval <= Z_LVAL_P(rhs) ? lhs : rhs);
} else if (Z_TYPE_P(rhs) == IS_DOUBLE && (zend_dval_to_lval_silent((double) lhs_lval) == lhs_lval)) {
/* if lhs_lval can be exactly represented as a double, go to double dedicated code */
lhs_dval = (double) lhs_lval;
Expand All @@ -1224,16 +1224,16 @@ ZEND_FRAMELESS_FUNCTION(min, 2)

if (EXPECTED(Z_TYPE_P(rhs) == IS_DOUBLE)) {
double_compare:
RETURN_COPY_VALUE(lhs_dval < Z_DVAL_P(rhs) ? lhs : rhs);
RETURN_COPY_VALUE(lhs_dval <= Z_DVAL_P(rhs) ? lhs : rhs);
} else if (Z_TYPE_P(rhs) == IS_LONG && (zend_dval_to_lval_silent((double) Z_LVAL_P(rhs)) == Z_LVAL_P(rhs))) {
/* if the value can be exactly represented as a double, use double dedicated code otherwise generic */
RETURN_COPY_VALUE(lhs_dval < (double)Z_LVAL_P(rhs) ? lhs : rhs);
RETURN_COPY_VALUE(lhs_dval <= (double)Z_LVAL_P(rhs) ? lhs : rhs);
} else {
goto generic_compare;
}
} else {
generic_compare:
RETURN_COPY(zend_compare(lhs, rhs) < 0 ? lhs : rhs);
RETURN_COPY(zend_compare(lhs, rhs) <= 0 ? lhs : rhs);
}
}

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32 changes: 32 additions & 0 deletions ext/standard/tests/array/gh20221.phpt
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@@ -0,0 +1,32 @@
--TEST--
GH-20221 (min()/max() tie-break inconsistently on signed zero via the 2-arg frameless fast path)
--FILE--
<?php

$negZero = -0.0;

// Direct calls with exactly two positional arguments are compiled to the
// frameless min()/max() opcodes, which used to break ties on -0.0 vs 0
// differently from every other min()/max() code path (and from each other).
var_dump(min($negZero, 0));
var_dump(max($negZero, 0));
var_dump(min(0, $negZero));
var_dump(max(0, $negZero));

// The variadic (3+ args) and array forms already resolved ties in favor of
// the first-seen operand; the frameless 2-arg results above must now agree.
var_dump(min($negZero, 0, 0));
var_dump(max($negZero, 0, 0));
var_dump(min([$negZero, 0]));
var_dump(max([$negZero, 0]));

?>
--EXPECT--
float(-0)
float(-0)
int(0)
int(0)
float(-0)
float(-0)
float(-0)
float(-0)
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