Warn when coercing NAN to other types #19573
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arnaud-lb
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Aug 29, 2025
Zend/Optimizer/dce.c
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| case ZEND_CAST: { | ||
| uint32_t t1 = OP1_INFO(); | ||
| /* Cast from NAN emits warning */ | ||
| if (t1 & MAY_BE_DOUBLE) { | ||
| return true; | ||
| } | ||
| if (t1 & MAY_BE_ARRAY) { | ||
| /* Array cast to string emits warning */ | ||
| return opline->extended_value == IS_STRING; | ||
| } | ||
| return false; | ||
| } | ||
| case ZEND_BOOL: | ||
| case ZEND_BOOL_NOT: { | ||
| uint32_t t1 = OP1_INFO(); | ||
| /* Cast from NAN emits warning */ | ||
| if (t1 & MAY_BE_DOUBLE) { | ||
| return true; | ||
| } | ||
| return false; | ||
| } |
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Only zend_may_throw() needs to be modified:
* * We separate intrinsic side-effects from potential side-effects in the form of notices thrown
* by the instruction (in case we want to make this configurable). See may_have_side_effects() and
* zend_may_throw().
| @@ -7728,7 +7728,14 @@ static int zend_jit_bool_jmpznz(zend_jit_ctx *jit, const zend_op *opline, uint32 | |||
| if_double = ir_IF(ir_EQ(type, ir_CONST_U8(IS_DOUBLE))); | |||
| ir_IF_TRUE(if_double); | |||
| } | |||
| ref = ir_NE(jit_Z_DVAL(jit, op1_addr), ir_CONST_DOUBLE(0.0)); | |||
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|||
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Need to avoid calling zend_is_true() during compilation above when the value is a const nan, otherwise we emit two warnings here: (during tracing, then while compiling the trace)
echo (bool)NAN;There was a problem hiding this comment.
I've done a check, but now the function JIT doesn't emit a warning :/
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| * Those optimizations are not safe if the other operand end up being NAN | ||
| * as BOOL/BOOL_NOT will warn which IS_EQUAL/IS_NOT_EQUAL do not. |
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Triggered a benchmark to check the effect of this: valgrind shows no regression (changes are under 0.0x%).
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I do wonder if this is not actually a problem for switch cases too now that I think of.
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RFC: https://wiki.php.net/rfc/warnings-php-8-5#coercing_nan_to_other_types