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Keith Randall b657c00243 cmd/compile: add | operator to make rewrite rules more succinct
Instead of

(And64 x x) -> x
(And32 x x) -> x
(And16 x x) -> x
(And8  x x) -> x

we can now do:

(And(64|32|16|8) x x) -> x

Any part of an opcode can have a parenthesized, |-separated list of possibilites.
The rule is then expanded using each piece of the | combo.
If there are multiple | clauses, they get expanded in tandem.
(All the first positions, then all the second positions, etc.)
All places | opcodes appear must have the same count.

A more complicated example:

(MOV(L|SS)load [off1] {sym1} (LEAQ4 [off2] {sym2} ptr idx) mem) && is32Bit(off1+off2) && canMergeSym(sym1, sym2) ->
	(MOV(L|SS)loadidx4 [off1+off2] {mergeSym(sym1,sym2)} ptr idx mem)

This meta-rule generates 2 rules, a MOVL and a MOVSS rule.

This CL is carefully orchestrated to not change the generated rules file at all.
In some cases, this means we can't align the rules nicely because it changes
the whitespace in the generated code.  I'll clean that up as a separate step.

There are many more opportunites to compactify rules using this new mechanism.
I've just done some examples, there's more to do.

Change-Id: I8a5e748cd0761ccbb12d09b01925b2f1f4b2f608
Reviewed-on: https://go-review.googlesource.com/86595
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2018-02-19 22:23:40 +00:00
.github github: add a Pull Request template 2018-02-14 16:13:49 +00:00
api syscall: support Getwd on all BSDs 2018-02-13 15:41:19 +00:00
doc doc: improve clarity of map index examples 2018-02-19 05:48:39 +00:00
lib/time all: use HTTPS for iana.org links 2018-02-13 18:36:48 +00:00
misc misc/cgo/testcshared: increase sleep in TestUnexportedSymbols 2018-02-14 15:03:29 +00:00
src cmd/compile: add | operator to make rewrite rules more succinct 2018-02-19 22:23:40 +00:00
test runtime: use sparse mappings for the heap 2018-02-15 21:12:23 +00:00
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AUTHORS A+C: update late Go 1.10 contributors 2018-01-06 04:52:00 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS A+C: update late Go 1.10 contributors 2018-01-06 04:52:00 +00:00
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