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| author | Kaz Kylheku <kaz@kylheku.com> | 2021-02-27 12:17:46 -0800 |
|---|---|---|
| committer | Kaz Kylheku <kaz@kylheku.com> | 2021-02-27 12:17:46 -0800 |
| commit | b0b7a05c76fac4dc072e394731a7e5f153c775a8 (patch) | |
| tree | b99f4eb06a0a7f89b81209882c2dbc07adab32bf | |
| parent | c3174f915dbcd5cd90659279671b9a3005b840ea (diff) | |
| download | txr-b0b7a05c76fac4dc072e394731a7e5f153c775a8.tar.gz txr-b0b7a05c76fac4dc072e394731a7e5f153c775a8.tar.bz2 txr-b0b7a05c76fac4dc072e394731a7e5f153c775a8.zip | |
compiler: optimize useless if to jmp.
* share/txr/stdlib/optimize.tl (basic-blocks
thread-jumps-block): This is a complementary optimization to
the one which matches (if (d @reg) @jlabel). An if
instruction conditional on the nil register (t 0) is always
taken, and can be rewritten to a jmp. This can promote
elimination of dead code.
| -rw-r--r-- | share/txr/stdlib/optimize.tl | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/share/txr/stdlib/optimize.tl b/share/txr/stdlib/optimize.tl index 259a64ae..81536c32 100644 --- a/share/txr/stdlib/optimize.tl +++ b/share/txr/stdlib/optimize.tl @@ -258,6 +258,8 @@ (set insn ninsn ninsn (match-case insn ((if (d @reg) @jlabel) nil) + ((if (t 0) @jlabel) + ^(jmp ,jlabel)) ((jmp @jlabel) (let ((jinsns [bb.hash jlabel].insns)) (match-case jinsns |