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0826a54836
When encountering the following SSA graph:
BB1:
#2.T1 [string] = COALESCE #1.CV0($str) [null, string] BB2
BB2:
#5.T1 [string] = QM_ASSIGN string("")
BB3:
#7.X1 [string] = Phi(#2.X1 [string], #5.X1 [string])
FREE #7.T1 [string]
We would currently determine that #7, #5 are dead, and eliminate
the FREE and QM_ASSIGN. However, we cannot eliminate #2, as
COALESCE is also responsible for control flow.
Fix this my marking all non-CV phis as live to start with. This
can be relaxed to check the kind of the source instruction, but
I couldn't immediately come up with a case where it would be
useful.
72 lines
1.4 KiB
PHP
72 lines
1.4 KiB
PHP
--TEST--
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DCE 009: Foreach over empty array is a no-op
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--INI--
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opcache.enable=1
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opcache.enable_cli=1
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opcache.optimization_level=-1
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opcache.opt_debug_level=0x20000
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opcache.preload=
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--EXTENSIONS--
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opcache
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--FILE--
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<?php
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class Loop {
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const VALUES = [];
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public static function test() {
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echo "Start\n";
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$y = [];
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foreach ($y as $x) {
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}
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echo "Done\n";
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}
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public static function test2() {
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foreach (self::VALUES as $x) {
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}
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}
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public static function test3() {
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foreach ([] as $k => &$v) {
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}
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}
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}
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Loop::test();
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Loop::test2();
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Loop::test3();
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--EXPECTF--
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$_main:
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; (lines=7, args=0, vars=0, tmps=0)
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; (after optimizer)
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; %sdce_009.php:1-23
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0000 INIT_STATIC_METHOD_CALL 0 string("Loop") string("test")
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0001 DO_UCALL
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0002 INIT_STATIC_METHOD_CALL 0 string("Loop") string("test2")
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0003 DO_UCALL
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0004 INIT_STATIC_METHOD_CALL 0 string("Loop") string("test3")
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0005 DO_UCALL
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0006 RETURN int(1)
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Loop::test:
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; (lines=3, args=0, vars=0, tmps=0)
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; (after optimizer)
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; %sdce_009.php:4-10
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0000 ECHO string("Start
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")
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0001 ECHO string("Done
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")
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0002 RETURN null
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Loop::test2:
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; (lines=1, args=0, vars=0, tmps=0)
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; (after optimizer)
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; %sdce_009.php:11-14
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0000 RETURN null
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Loop::test3:
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; (lines=3, args=0, vars=0, tmps=1)
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; (after optimizer)
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; %sdce_009.php:15-18
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0000 V0 = FE_RESET_RW array(...) 0001
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0001 FE_FREE V0
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0002 RETURN null
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Start
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Done
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