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cmd/compile: PPC64, elide unnecessary sign extension

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Inputs to store[BHW] and cmpW(U) need not be correct
in more bits than are used by the instruction.

Added a pattern tailored to what appears to be cgo boilerplate.
Added a pattern (also seen in cgo boilerplate and hashing)
to replace {EQ,NE}-CMP-ANDconst with {EQ-NE}-ANDCCconst.
Added a pattern to clean up ANDconst shift distance inputs
(this was seen in hashing).

Simplify repeated and,or,xor.

Fixes #17109.

Change-Id: I68eac83e3e614d69ffe473a08953048c8b066d88
Reviewed-on: https://go-review.googlesource.com/30455
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
David Chase 2016-10-05 13:21:09 -07:00
parent 672e579444
commit 2f0b8f88df
6 changed files with 1192 additions and 60 deletions
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7
src/cmd/compile/internal/ssa/rewrite.go
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@ -229,11 +229,16 @@ func is16Bit(n int64) bool {
return n == int64(int16(n))
}
// is16Bit reports whether n can be represented as an unsigned 16 bit integer.
// isU16Bit reports whether n can be represented as an unsigned 16 bit integer.
func isU16Bit(n int64) bool {
return n == int64(uint16(n))
}
// isU32Bit reports whether n can be represented as an unsigned 32 bit integer.
func isU32Bit(n int64) bool {
return n == int64(uint32(n))
}
// is20Bit reports whether n can be represented as a signed 20 bit integer.
func is20Bit(n int64) bool {
return -(1<<19) <= n && n < (1<<19)