1. 27 Apr, 2018 10 commits
  2. 26 Apr, 2018 24 commits
  3. 25 Apr, 2018 6 commits
    • Josh Bleecher Snyder's avatar
      cmd/compile: use intrinsic for LeadingZeros8 on amd64 · c5f0104d
      Josh Bleecher Snyder authored
      The previous change sped up the pure computation form of LeadingZeros8.
      This places it somewhat close to the table lookup form.
      Depending on something that varies from toolchain to toolchain
      (alignment, perhaps?), the slowdown from ditching the table lookup
      is either 20% or 5%.
      
      This benchmark is the best case scenario for the table lookup:
      It is in the L1 cache already.
      
      I think we're close enough that we can switch to the computational version,
      and trust that the memory effects and binary size savings will be worth it.
      
      Code:
      
      func f8(x uint8)   { z = bits.LeadingZeros8(x) }
      
      Before:
      
      "".f8 STEXT nosplit size=34 args=0x8 locals=0x0
      	0x0000 00000 (x.go:7)	TEXT	"".f8(SB), NOSPLIT, $0-8
      	0x0000 00000 (x.go:7)	FUNCDATA	$0, gclocals·2a5305abe05176240e61b8620e19a815(SB)
      	0x0000 00000 (x.go:7)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
      	0x0000 00000 (x.go:7)	MOVBLZX	"".x+8(SP), AX
      	0x0005 00005 (x.go:7)	MOVBLZX	AL, AX
      	0x0008 00008 (x.go:7)	LEAQ	math/bits.len8tab(SB), CX
      	0x000f 00015 (x.go:7)	MOVBLZX	(CX)(AX*1), AX
      	0x0013 00019 (x.go:7)	ADDQ	$-8, AX
      	0x0017 00023 (x.go:7)	NEGQ	AX
      	0x001a 00026 (x.go:7)	MOVQ	AX, "".z(SB)
      	0x0021 00033 (x.go:7)	RET
      
      After:
      
      "".f8 STEXT nosplit size=30 args=0x8 locals=0x0
      	0x0000 00000 (x.go:7)	TEXT	"".f8(SB), NOSPLIT, $0-8
      	0x0000 00000 (x.go:7)	FUNCDATA	$0, gclocals·2a5305abe05176240e61b8620e19a815(SB)
      	0x0000 00000 (x.go:7)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
      	0x0000 00000 (x.go:7)	MOVBLZX	"".x+8(SP), AX
      	0x0005 00005 (x.go:7)	MOVBLZX	AL, AX
      	0x0008 00008 (x.go:7)	LEAL	1(AX)(AX*1), AX
      	0x000c 00012 (x.go:7)	BSRL	AX, AX
      	0x000f 00015 (x.go:7)	ADDQ	$-8, AX
      	0x0013 00019 (x.go:7)	NEGQ	AX
      	0x0016 00022 (x.go:7)	MOVQ	AX, "".z(SB)
      	0x001d 00029 (x.go:7)	RET
      
      Change-Id: Icc7db50a7820fb9a3da8a816d6b6940d7f8e193e
      Reviewed-on: https://go-review.googlesource.com/108942
      Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
      TryBot-Result: Gobot Gobot <gobot@golang.org>
      Reviewed-by: default avatarKeith Randall <khr@golang.org>
      c5f0104d
    • Josh Bleecher Snyder's avatar
      cmd/compile: optimize LeadingZeros(16|32) on amd64 · 1d321ada
      Josh Bleecher Snyder authored
      Introduce Len8 and Len16 ops and provide optimized lowerings for them.
      amd64 only for this CL, although it wouldn't surprise me
      if other architectures also admit of optimized lowerings.
      
      Also use and optimize the Len32 lowering, along the same lines.
      
      Leave Len8 unused for the moment; a subsequent CL will enable it.
      
      For 16 and 32 bits, this leads to a speed-up.
      
      name              old time/op  new time/op  delta
      LeadingZeros16-8  1.42ns ± 5%  1.23ns ± 5%  -13.42%  (p=0.000 n=20+20)
      LeadingZeros32-8  1.25ns ± 5%  1.03ns ± 5%  -17.63%  (p=0.000 n=20+16)
      
      Code:
      
      func f16(x uint16) { z = bits.LeadingZeros16(x) }
      func f32(x uint32) { z = bits.LeadingZeros32(x) }
      
      Before:
      
      "".f16 STEXT nosplit size=38 args=0x8 locals=0x0
      	0x0000 00000 (x.go:8)	TEXT	"".f16(SB), NOSPLIT, $0-8
      	0x0000 00000 (x.go:8)	FUNCDATA	$0, gclocals·2a5305abe05176240e61b8620e19a815(SB)
      	0x0000 00000 (x.go:8)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
      	0x0000 00000 (x.go:8)	MOVWLZX	"".x+8(SP), AX
      	0x0005 00005 (x.go:8)	MOVWLZX	AX, AX
      	0x0008 00008 (x.go:8)	BSRQ	AX, AX
      	0x000c 00012 (x.go:8)	MOVQ	$-1, CX
      	0x0013 00019 (x.go:8)	CMOVQEQ	CX, AX
      	0x0017 00023 (x.go:8)	ADDQ	$-15, AX
      	0x001b 00027 (x.go:8)	NEGQ	AX
      	0x001e 00030 (x.go:8)	MOVQ	AX, "".z(SB)
      	0x0025 00037 (x.go:8)	RET
      
      "".f32 STEXT nosplit size=34 args=0x8 locals=0x0
      	0x0000 00000 (x.go:9)	TEXT	"".f32(SB), NOSPLIT, $0-8
      	0x0000 00000 (x.go:9)	FUNCDATA	$0, gclocals·2a5305abe05176240e61b8620e19a815(SB)
      	0x0000 00000 (x.go:9)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
      	0x0000 00000 (x.go:9)	MOVL	"".x+8(SP), AX
      	0x0004 00004 (x.go:9)	BSRQ	AX, AX
      	0x0008 00008 (x.go:9)	MOVQ	$-1, CX
      	0x000f 00015 (x.go:9)	CMOVQEQ	CX, AX
      	0x0013 00019 (x.go:9)	ADDQ	$-31, AX
      	0x0017 00023 (x.go:9)	NEGQ	AX
      	0x001a 00026 (x.go:9)	MOVQ	AX, "".z(SB)
      	0x0021 00033 (x.go:9)	RET
      
      After:
      
      "".f16 STEXT nosplit size=30 args=0x8 locals=0x0
      	0x0000 00000 (x.go:8)	TEXT	"".f16(SB), NOSPLIT, $0-8
      	0x0000 00000 (x.go:8)	FUNCDATA	$0, gclocals·2a5305abe05176240e61b8620e19a815(SB)
      	0x0000 00000 (x.go:8)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
      	0x0000 00000 (x.go:8)	MOVWLZX	"".x+8(SP), AX
      	0x0005 00005 (x.go:8)	MOVWLZX	AX, AX
      	0x0008 00008 (x.go:8)	LEAL	1(AX)(AX*1), AX
      	0x000c 00012 (x.go:8)	BSRL	AX, AX
      	0x000f 00015 (x.go:8)	ADDQ	$-16, AX
      	0x0013 00019 (x.go:8)	NEGQ	AX
      	0x0016 00022 (x.go:8)	MOVQ	AX, "".z(SB)
      	0x001d 00029 (x.go:8)	RET
      
      "".f32 STEXT nosplit size=28 args=0x8 locals=0x0
      	0x0000 00000 (x.go:9)	TEXT	"".f32(SB), NOSPLIT, $0-8
      	0x0000 00000 (x.go:9)	FUNCDATA	$0, gclocals·2a5305abe05176240e61b8620e19a815(SB)
      	0x0000 00000 (x.go:9)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
      	0x0000 00000 (x.go:9)	MOVL	"".x+8(SP), AX
      	0x0004 00004 (x.go:9)	LEAQ	1(AX)(AX*1), AX
      	0x0009 00009 (x.go:9)	BSRQ	AX, AX
      	0x000d 00013 (x.go:9)	ADDQ	$-32, AX
      	0x0011 00017 (x.go:9)	NEGQ	AX
      	0x0014 00020 (x.go:9)	MOVQ	AX, "".z(SB)
      	0x001b 00027 (x.go:9)	RET
      
      Change-Id: I6c93c173752a7bfdeab8be30777ae05a736e1f4b
      Reviewed-on: https://go-review.googlesource.com/108941
      Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
      TryBot-Result: Gobot Gobot <gobot@golang.org>
      Reviewed-by: default avatarGiovanni Bajo <rasky@develer.com>
      Reviewed-by: default avatarKeith Randall <khr@golang.org>
      1d321ada
    • Josh Bleecher Snyder's avatar
      cmd/compile: optimize TrailingZeros(8|16) on amd64 · 54dbab52
      Josh Bleecher Snyder authored
      Introduce Ctz8 and Ctz16 ops and provide optimized lowerings for them.
      amd64 only for this CL, although it wouldn't surprise me
      if other architectures also admit of optimized lowerings.
      
      name               old time/op  new time/op  delta
      TrailingZeros8-8   1.33ns ± 6%  0.84ns ± 3%  -36.90%  (p=0.000 n=20+20)
      TrailingZeros16-8  1.26ns ± 5%  0.84ns ± 5%  -33.50%  (p=0.000 n=20+18)
      
      Code:
      
      func f8(x uint8)   { z = bits.TrailingZeros8(x) }
      func f16(x uint16) { z = bits.TrailingZeros16(x) }
      
      Before:
      
      "".f8 STEXT nosplit size=34 args=0x8 locals=0x0
      	0x0000 00000 (x.go:7)	TEXT	"".f8(SB), NOSPLIT, $0-8
      	0x0000 00000 (x.go:7)	FUNCDATA	$0, gclocals·2a5305abe05176240e61b8620e19a815(SB)
      	0x0000 00000 (x.go:7)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
      	0x0000 00000 (x.go:7)	MOVBLZX	"".x+8(SP), AX
      	0x0005 00005 (x.go:7)	MOVBLZX	AL, AX
      	0x0008 00008 (x.go:7)	BTSQ	$8, AX
      	0x000d 00013 (x.go:7)	BSFQ	AX, AX
      	0x0011 00017 (x.go:7)	MOVL	$64, CX
      	0x0016 00022 (x.go:7)	CMOVQEQ	CX, AX
      	0x001a 00026 (x.go:7)	MOVQ	AX, "".z(SB)
      	0x0021 00033 (x.go:7)	RET
      
      "".f16 STEXT nosplit size=34 args=0x8 locals=0x0
      	0x0000 00000 (x.go:8)	TEXT	"".f16(SB), NOSPLIT, $0-8
      	0x0000 00000 (x.go:8)	FUNCDATA	$0, gclocals·2a5305abe05176240e61b8620e19a815(SB)
      	0x0000 00000 (x.go:8)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
      	0x0000 00000 (x.go:8)	MOVWLZX	"".x+8(SP), AX
      	0x0005 00005 (x.go:8)	MOVWLZX	AX, AX
      	0x0008 00008 (x.go:8)	BTSQ	$16, AX
      	0x000d 00013 (x.go:8)	BSFQ	AX, AX
      	0x0011 00017 (x.go:8)	MOVL	$64, CX
      	0x0016 00022 (x.go:8)	CMOVQEQ	CX, AX
      	0x001a 00026 (x.go:8)	MOVQ	AX, "".z(SB)
      	0x0021 00033 (x.go:8)	RET
      
      After:
      
      "".f8 STEXT nosplit size=20 args=0x8 locals=0x0
      	0x0000 00000 (x.go:7)	TEXT	"".f8(SB), NOSPLIT, $0-8
      	0x0000 00000 (x.go:7)	FUNCDATA	$0, gclocals·2a5305abe05176240e61b8620e19a815(SB)
      	0x0000 00000 (x.go:7)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
      	0x0000 00000 (x.go:7)	MOVBLZX	"".x+8(SP), AX
      	0x0005 00005 (x.go:7)	BTSL	$8, AX
      	0x0009 00009 (x.go:7)	BSFL	AX, AX
      	0x000c 00012 (x.go:7)	MOVQ	AX, "".z(SB)
      	0x0013 00019 (x.go:7)	RET
      
      "".f16 STEXT nosplit size=20 args=0x8 locals=0x0
      	0x0000 00000 (x.go:8)	TEXT	"".f16(SB), NOSPLIT, $0-8
      	0x0000 00000 (x.go:8)	FUNCDATA	$0, gclocals·2a5305abe05176240e61b8620e19a815(SB)
      	0x0000 00000 (x.go:8)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
      	0x0000 00000 (x.go:8)	MOVWLZX	"".x+8(SP), AX
      	0x0005 00005 (x.go:8)	BTSL	$16, AX
      	0x0009 00009 (x.go:8)	BSFL	AX, AX
      	0x000c 00012 (x.go:8)	MOVQ	AX, "".z(SB)
      	0x0013 00019 (x.go:8)	RET
      
      Change-Id: I0551e357348de2b724737d569afd6ac9f5c3aa11
      Reviewed-on: https://go-review.googlesource.com/108940
      Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
      TryBot-Result: Gobot Gobot <gobot@golang.org>
      Reviewed-by: default avatarGiovanni Bajo <rasky@develer.com>
      Reviewed-by: default avatarKeith Randall <khr@golang.org>
      54dbab52
    • Russ Cox's avatar
      cmd/go/internal/load: split test logic out of pkg.go into test.go · 90083e65
      Russ Cox authored
      It's going to grow.
      
      Change-Id: I4f5d3cce6e03250508d1ae0981a6d82a4192ae31
      Reviewed-on: https://go-review.googlesource.com/107915
      Run-TryBot: Russ Cox <rsc@golang.org>
      Reviewed-by: default avatarBryan C. Mills <bcmills@google.com>
      90083e65
    • Russ Cox's avatar
      cmd/go: add go list -deps · 90e860f1
      Russ Cox authored
      This gives an easy way to query properties of all the deps
      of a set of packages, in a single go list invocation.
      Go list has already done the hard work of loading these
      packages, so exposing them is more efficient than
      requiring a second invocation.
      
      This will be helpful for tools asking cmd/go about build
      information.
      
      Change-Id: I90798e386246b24aad92dd13cb9e3788c7d30e91
      Reviewed-on: https://go-review.googlesource.com/107776
      Run-TryBot: Russ Cox <rsc@golang.org>
      TryBot-Result: Gobot Gobot <gobot@golang.org>
      Reviewed-by: default avatarBryan C. Mills <bcmills@google.com>
      90e860f1
    • Ian Lance Taylor's avatar
      misc/cgo/test: log error value in testSigprocmask · 9c9ed9aa
      Ian Lance Taylor authored
      The test has been flaky, probably due to EAGAIN, but let's find out
      for sure.
      
      Updates #25078
      
      Change-Id: I5a5b14bfc52cb43f25f07ca7d207b61ae9d4f944
      Reviewed-on: https://go-review.googlesource.com/109359
      Run-TryBot: Ian Lance Taylor <iant@golang.org>
      Reviewed-by: default avatarBryan C. Mills <bcmills@google.com>
      9c9ed9aa