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Michael Munday 58cdecb9c8 cmd/compile: generate constants for NeqPtr, EqPtr and IsNonNil ops
If both inputs are constant offsets from the same pointer then we
can evaluate NeqPtr and EqPtr at compile time. Triggers a few times
during all.bash. Removes a conditional branch in the following
code:

copy(x[1:], x[:])

This branch was recently added as an optimization in CL 94596. We
now skip the memmove if the pointers are equal. However, in the
above code we know at compile time that they are never equal.

Also, when the offset is variable, check if the offset is zero
rather than if the pointers are equal. For example:

copy(x[a:], x[:])

This would now skip the copy if a == 0, rather than if x + a == x.

Finally I've also added a rule to make IsNonNil true for pointers
to values on the stack. The nil check elimination pass will catch
these anyway, but eliminating them here might eliminate branches
earlier.

Change-Id: If72f436fef0a96ad0f4e296d3a1f8b6c3e712085
Reviewed-on: https://go-review.googlesource.com/106635
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2018-04-16 20:43:57 +00:00
.github github: update Pull Request template 2018-02-21 02:07:46 +00:00
api api: remove unnecessary lines from except.txt 2018-04-09 21:19:11 +00:00
doc doc: clarify package uninstall/clean command 2018-04-16 19:54:55 +00:00
lib/time all: use HTTPS for iana.org links 2018-02-13 18:36:48 +00:00
misc misc/ios: speed up the iOS exec wrapper 2018-04-12 19:30:54 +00:00
src cmd/compile: generate constants for NeqPtr, EqPtr and IsNonNil ops 2018-04-16 20:43:57 +00:00
test cmd/compile: generate constants for NeqPtr, EqPtr and IsNonNil ops 2018-04-16 20:43:57 +00:00
.gitattributes
.gitignore .gitignore: ignore src/cmd/dist/dist 2017-10-28 21:55:49 +00:00
AUTHORS A+C: update email address 2018-04-14 19:28:37 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS C: add Iskander Sharipov's individual CLA mail 2018-04-16 04:49:46 +00:00
favicon.ico website: recreate 16px and 32px favicon 2016-08-25 15:43:32 +00:00
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README.md README: update number of contributors 2018-04-03 22:10:32 +00:00
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