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[dev.ssa] cmd/compile: rewrite user nil check as OpIsNonNil

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Rewite user nil checks as OpIsNonNil so our nil check elimination pass
can take advantage and remove redundant checks.

With make.bash this removes 10% more nilchecks (34110 vs 31088).

Change-Id: Ifb01d1b6d2d759f5e2a5aaa0470e1d5a2a680212
Reviewed-on: https://go-review.googlesource.com/14321
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This commit is contained in:
Todd Neal 2015-08-30 21:19:20 -05:00
parent 617e892b87
commit ec8a597cd2
6 changed files with 136 additions and 9 deletions
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2
src/cmd/compile/internal/ssa/compile.go
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@ -121,6 +121,8 @@ var passOrder = [...]constraint{
{"nilcheckelim", "generic deadcode"},
// nilcheckelim generates sequences of plain basic blocks
{"nilcheckelim", "fuse"},
// nilcheckelim relies on opt to rewrite user nil checks
{"opt", "nilcheckelim"},
// tighten should happen before lowering to avoid splitting naturally paired instructions such as CMP/SET
{"tighten", "lower"},
// tighten will be most effective when as many values have been removed as possible