From 82aee83fa4e280007c4146053202e22c2754211b Mon Sep 17 00:00:00 2001 From: Kaz Kylheku Date: Wed, 10 Nov 2021 07:06:25 -0800 Subject: compiler: late-peephole match for a wasteful register move. I've noticed a wasteful instruction pattern in the compiled code for the sys:awk-code-move-check function: 7: 2C020007 movsr t2 t7 8: 3800000E if t7 14 9: 00000007 10: 20050002 gcall t2 1 t9 d1 t8 t6 t7 11: 00090001 12: 00080401 13: 00070006 14: 10000002 end t2 Here, the t2 register can be replaced with t7 in the gcall and end instructions, and the movsr t2 t7 instruction can be eliminated. It looks like something that could somehow be targeted more generally with a clever peephole pattern assisted by data-flow information, but for now I'm sticking in a dumb late-peephole pattern which just looks for this very specific pattern. * stdlib/optimize.tl (basic-blocks late-peephole): Add new pattern for eliminating the move, as described above. There are several hits for this in the standard library in addition to the awk module: in the path-test, each-prod and getopts files. --- stdlib/optimize.tl | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/stdlib/optimize.tl b/stdlib/optimize.tl index a947c715..52b39182 100644 --- a/stdlib/optimize.tl +++ b/stdlib/optimize.tl @@ -612,6 +612,19 @@ (ifq (t ,tn) (t 0) ,lab4) ,lab5 ,*rest))) + (((mov (t @tx) (t @ty)) + (if (t @ty) @lab2) + @(symbolp @lab1) + (gcall (t @tx) . @args) + @(symbolp @lab2) + (jend (t @tx)) + . @rest) + ^((if (t ,ty) ,lab2) + ,lab1 + (gcall (t ,ty) ,*args) + ,lab2 + (end (t ,ty)) + ,*rest)) (@else else))) (defun rewrite (fun list) -- cgit v1.2.3