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2018-03-08cmd/compile: make prove pass use unsatisfiabilityAustin Clements
Currently the prove pass uses implication queries. For each block, it collects the set of branch conditions leading to that block, and queries this fact table for whether any of these facts imply the block's own branch condition (or its inverse). This works remarkably well considering it doesn't do any deduction on these facts, but it has various downsides: 1. It requires an implementation both of adding facts to the table and determining implications. These are very nearly duals of each other, but require separate implementations. Likewise, the process of asserting facts of dominating branch conditions is very nearly the dual of the process of querying implied branch conditions. 2. It leads to less effective use of derived facts. For example, the prove pass currently derives facts about the relations between len and cap, but can't make use of these unless a branch condition is in the exact form of a derived fact. If one of these derived facts contradicts another fact, it won't notice or make use of this. This CL changes the approach of the prove pass to instead use *contradiction* instead of implication. Rather than ever querying a branch condition, it simply adds branch conditions to the fact table. If this leads to a contradiction (specifically, it makes the fact set unsatisfiable), that branch is impossible and can be cut. As a result, 1. We can eliminate the code for determining implications (factsTable.get disappears entirely). Also, there is now a single implementation of visiting and asserting branch conditions, since we don't have to flip them around to treat them as facts in one place and queries in another. 2. Derived facts can be used effectively. It doesn't matter *why* the fact table is unsatisfiable; a contradiction in any of the facts is enough. 3. As an added benefit, it's now quite easy to avoid traversing beyond provably-unreachable blocks. In contrast, the current implementation always visits all blocks. The prove pass already has nearly all of the mechanism necessary to compute unsatisfiability, which means this both simplifies the code and makes it more powerful. The only complication is that the current implication procedure has a hack for dealing with the 0 <= Args[0] condition of OpIsInBounds and OpIsSliceInBounds. We replace this with asserting the appropriate fact when we process one of these conditions. This seems much cleaner anyway, and works because we can now take advantage of derived facts. This has no measurable effect on compiler performance. Effectiveness: There is exactly one condition in all of std and cmd that this fails to prove that the old implementation could: (int64(^uint(0)>>1) < x) in encoding/gob. This can never be true because x is an int, and it's basically coincidence that the old code gets this. (For example, it fails to prove the similar (x < ^int64(^uint(0)>>1)) condition that immediately precedes it, and even though the conditions are logically unrelated, it wouldn't get the second one if it hadn't first processed the first!) It does, however, prove a few dozen additional branches. These come from facts that are added to the fact table about the relations between len and cap. These were almost never queried directly before, but could lead to contradictions, which the unsat-based approach is able to use. There are exactly two branches in std and cmd that this implementation proves in the *other* direction. This sounds scary, but is okay because both occur in already-unreachable blocks, so it doesn't matter what we chose. Because the fact table logic is sound but incomplete, it fails to prove that the block isn't reachable, even though it is able to prove that both outgoing branches are impossible. We could turn these blocks into BlockExit blocks, but it doesn't seem worth the trouble of the extra proof effort for something that happens twice in all of std and cmd. Tests: This CL updates test/prove.go to change the expected messages because it can no longer give a "reason" why it proved or disproved a condition. It also adds a new test of a branch it couldn't prove before. It mostly guts test/sliceopt.go, removing everything related to slice bounds optimizations and moving a few relevant tests to test/prove.go. Much of this test is actually unreachable. The new prove pass figures this out and doesn't try to prove anything about the unreachable parts. The output on the unreachable parts is already suspect because anything can be proved at that point, so it's really just a regression test for an algorithm the compiler no longer uses. This is a step toward fixing #23354. That issue is quite easy to fix once we can use derived facts effectively. Change-Id: Ia48a1b9ee081310579fe474e4a61857424ff8ce8 Reviewed-on: https://go-review.googlesource.com/87478 Reviewed-by: Keith Randall <khr@golang.org>
2016-10-27cmd/compile: use masks instead of branches for slicingKeith Randall
When we do var x []byte = ... y := x[i:] We can't just use y.ptr = x.ptr + i, as the new pointer may point to the next object in memory after the backing array. We used to fix this by doing: y.cap = x.cap - i delta := i if y.cap == 0 { delta = 0 } y.ptr = x.ptr + delta That generates a branch in what is otherwise straight-line code. Better to do: y.cap = x.cap - i mask := (y.cap - 1) >> 63 // -1 if y.cap==0, 0 otherwise y.ptr = x.ptr + i &^ mask It's about the same number of instructions (~4, depending on what parts are constant, and the target architecture), but it is all inline. It plays nicely with CSE, and the mask can be computed in parallel with the index (in cases where a multiply is required). It is a minor win in both speed and space. Change-Id: Ied60465a0b8abb683c02208402e5bb7ac0e8370f Reviewed-on: https://go-review.googlesource.com/32022 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Cherry Zhang <cherryyz@google.com>
2016-10-20cmd/compile: Repurpose old sliceopt.go for prove phase.David Chase
Adapt old test for prove's bounds check elimination. Added missing rule to generic rules that lead to differences between 32 and 64 bit platforms on sliceopt test. Added debugging to prove.go that was helpful-to-necessary to discover that missing rule. Lowered debugging level on prove.go from 3 to 1; no idea why it was previously 3. Change-Id: I09de206aeb2fced9f2796efe2bfd4a59927eda0c Reviewed-on: https://go-review.googlesource.com/23290 Run-TryBot: David Chase <drchase@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
2016-10-06test: delete sliceopt.goDavid Chase
It tests the behavior of the old deleted compiler. Fixes #17362. Change-Id: Ia2fdec734c5cbe724a9de562ed71598f67244ab3 Reviewed-on: https://go-review.googlesource.com/30593 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2016-09-13cmd/compile: add SSA backend for s390x and enable by defaultMichael Munday
The new SSA backend modifies the ABI slightly: R0 is now a usable general purpose register. Fixes #16677. Change-Id: I367435ce921e0c7e79e021c80cf8ef5d1d1466cf Reviewed-on: https://go-review.googlesource.com/28978 Run-TryBot: Michael Munday <munday@ca.ibm.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
2016-08-26cmd/compile: add MIPS64 optimizations, SSA on by defaultCherry Zhang
Add the following optimizations: - fold constants - fold address into load/store - simplify extensions and conditional branches - remove nil checks Turn on SSA on MIPS64 by default, and toggle the tests. Fixes #16359. Change-Id: I7f1e38c2509e22e42cd024e712990ebbe47176bd Reviewed-on: https://go-review.googlesource.com/27870 Run-TryBot: Cherry Zhang <cherryyz@google.com> Reviewed-by: David Chase <drchase@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-08-18cmd/compile: ppc64le working, not optimized enoughDavid Chase
This time with the cherry-pick from the proper patch of the old CL. Stack size increased. Corrected NaN-comparison glitches. Marked g register as clobbered by calls. Fixed shared libraries. live_ssa.go still disabled because of differences. Presumably turning on more optimization will fix both the stack size and the live_ssa.go glitches. Enhanced debugging output for shared libs test. Rebased onto master. Updates #16010. Change-Id: I40864faf1ef32c118fb141b7ef8e854498e6b2c4 Reviewed-on: https://go-review.googlesource.com/27159 Run-TryBot: David Chase <drchase@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Cherry Zhang <cherryyz@google.com>
2016-08-15[dev.ssa] cmd/compile, etc.: more ARM64 optimizations, and enable SSA by defaultCherry Zhang
Add more ARM64 optimizations: - use hardware zero register when it is possible. - use shifted ops. The assembler supports shifted ops but not documented, nor knows how to print it. This CL adds them. - enable fast division. This was disabled because it makes the old backend generate slower code. But with SSA it generates faster code. Turn on SSA by default, also adjust tests. Change-Id: I7794479954c83bb65008dcb457bc1e21d7496da6 Reviewed-on: https://go-review.googlesource.com/26950 Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: David Chase <drchase@google.com>
2016-08-10[dev.ssa] cmd/compile: implement GO386=387Keith Randall
Last part of the 386 SSA port. Modify the x86 backend to simulate SSE registers and instructions with 387 registers and instructions. The simulation isn't terribly performant, but it works, and the old implementation wasn't very performant either. Leaving to people who care about 387 to optimize if they want. Turn on SSA backend for 386 by default. Fixes #16358 Change-Id: I678fb59132620b2c47e993c1c10c4c21135f70c0 Reviewed-on: https://go-review.googlesource.com/25271 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
2016-08-09[dev.ssa] cmd/compile: port SSA backend to amd64p32Keith Randall
It's not a new backend, just a PtrSize==4 modification of the existing AMD64 backend. Change-Id: Icc63521a5cf4ebb379f7430ef3f070894c09afda Reviewed-on: https://go-review.googlesource.com/25586 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: David Chase <drchase@google.com>
2016-07-16[dev.ssa] cmd/compile: support NaCl in SSA for ARMCherry Zhang
NaCl code runs in sandbox and there are restrictions for its instruction uses (https://developer.chrome.com/native-client/reference/sandbox_internals/arm-32-bit-sandbox). Like the legacy backend, on NaCl, - don't use R9, which is used as NaCl's "thread pointer". - don't use Duff's device. - don't use indexed load/stores. - the assembler rewrites DIV/MOD to runtime calls, which on NaCl clobbers R12, so R12 is marked as clobbered for DIV/MOD. - other restrictions are satisfied by the assembler. Enable SSA specific tests on nacl/arm, and disable non-SSA ones. Updates #15365. Change-Id: I9262693ec6756b89ca29d3ae4e52a96fe5403b02 Reviewed-on: https://go-review.googlesource.com/24859 Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
2016-07-06[dev.ssa] cmd/compile: enable SSA on ARM by defaultCherry Zhang
As Josh mentioned in CL 24716, there has been requests for using SSA for ARM. SSA can still be disabled by setting -ssa=0 for cmd/compile, or partially enabled with GOSSAFUNC, GOSSAPKG, and GOSSAHASH. Not enable SSA by default on NaCl, which is not supported yet. Enable SSA-specific tests on ARM: live_ssa.go and nilptr3_ssa.go; disable non-SSA tests: live.go, nilptr3.go, and slicepot.go. Updates #15365. Change-Id: Ic2ca8d166aeca8517b9d262a55e92f2130683a16 Reviewed-on: https://go-review.googlesource.com/23953 Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com> Reviewed-by: David Chase <drchase@google.com>
2016-05-02all: make copyright headers consistent with one space after periodEmmanuel Odeke
Follows suit with https://go-review.googlesource.com/#/c/20111. Generated by running $ grep -R 'Go Authors. All' * | cut -d":" -f1 | while read F;do perl -pi -e 's/Go Authors. All/Go Authors. All/g' $F;done The code in cmd/internal/unvendor wasn't changed. Fixes #15213 Change-Id: I4f235cee0a62ec435f9e8540a1ec08ae03b1a75f Reviewed-on: https://go-review.googlesource.com/21819 Reviewed-by: Ian Lance Taylor <iant@golang.org> Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-10-30[dev.ssa] cmd/compile: default compile+test with SSADavid Chase
Some tests disabled, some bifurcated into _ssa and not, with appropriate logging added to compiler. "tests/live.go" in particular needs attention. SSA-specific testing removed, since it's all SSA now. Added "-run_skips" option to tests/run.go to simplify checking whether a test still fails (or how it fails) on a skipped platform. The compiler now compiles with SSA by default. If you don't want SSA, specify GOSSAHASH=n (or N) as an environment variable. Function names ending in "_ssa" are always SSA-compiled. GOSSAFUNC=fname retains its "SSA for fname, log to ssa.html" GOSSAPKG=pkg only has an effect when GOSSAHASH=n GOSSAHASH=10101 etc retains its name-hash-matching behavior for purposes of debugging. See #13068 Change-Id: I8217bfeb34173533eaeb391b5f6935483c7d6b43 Reviewed-on: https://go-review.googlesource.com/16299 Reviewed-by: Keith Randall <khr@golang.org> Run-TryBot: David Chase <drchase@google.com>
2015-05-13cmd/internal/gc: optimize slice + write barrierRuss Cox
The code generated for a slice x[i:j] or x[i:j:k] computes the entire new slice (base, len, cap) and then uses it as the evaluation of the slice expression. If the slice is part of an update x = x[i:j] or x = x[i:j:k], there are opportunities to avoid computing some of these fields. For x = x[0:i], we know that only the len is changing; base can be ignored completely, and cap can be left unmodified. For x = x[0:i:j], we know that only len and cap are changing; base can be ignored completely. For x = x[i:i], we know that the resulting cap is zero, and we don't adjust the base during a slice producing a zero-cap result, so again base can be ignored completely. No write to base, no write barrier. The old slice code was trying to work at a Go syntax level, mainly because that was how you wrote code just once instead of once per architecture. Now the compiler is factored a bit better and we can implement slice during code generation but still have one copy of the code. So the new code is working at that lower level. (It must, to update only parts of the result.) This CL by itself: name old mean new mean delta BinaryTree17 5.81s × (0.98,1.03) 5.71s × (0.96,1.05) ~ (p=0.101) Fannkuch11 4.35s × (1.00,1.00) 4.39s × (1.00,1.00) +0.79% (p=0.000) FmtFprintfEmpty 86.0ns × (0.94,1.11) 82.6ns × (0.98,1.04) -3.86% (p=0.048) FmtFprintfString 276ns × (0.98,1.04) 273ns × (0.98,1.02) ~ (p=0.235) FmtFprintfInt 274ns × (0.98,1.06) 270ns × (0.99,1.01) ~ (p=0.119) FmtFprintfIntInt 506ns × (0.99,1.01) 475ns × (0.99,1.01) -6.02% (p=0.000) FmtFprintfPrefixedInt 391ns × (0.99,1.01) 393ns × (1.00,1.01) ~ (p=0.139) FmtFprintfFloat 566ns × (0.99,1.01) 574ns × (1.00,1.01) +1.33% (p=0.001) FmtManyArgs 1.91µs × (0.99,1.01) 1.87µs × (0.99,1.02) -1.83% (p=0.000) GobDecode 15.3ms × (0.99,1.02) 15.0ms × (0.98,1.05) -1.84% (p=0.042) GobEncode 11.5ms × (0.97,1.03) 11.4ms × (0.99,1.03) ~ (p=0.152) Gzip 645ms × (0.99,1.01) 647ms × (0.99,1.01) ~ (p=0.265) Gunzip 142ms × (1.00,1.00) 143ms × (1.00,1.01) +0.90% (p=0.000) HTTPClientServer 90.5µs × (0.97,1.04) 88.5µs × (0.99,1.03) -2.27% (p=0.014) JSONEncode 32.0ms × (0.98,1.03) 29.6ms × (0.98,1.01) -7.51% (p=0.000) JSONDecode 114ms × (0.99,1.01) 104ms × (1.00,1.01) -8.60% (p=0.000) Mandelbrot200 6.04ms × (1.00,1.01) 6.02ms × (1.00,1.00) ~ (p=0.057) GoParse 6.47ms × (0.97,1.05) 6.37ms × (0.97,1.04) ~ (p=0.105) RegexpMatchEasy0_32 171ns × (0.93,1.07) 152ns × (0.99,1.01) -11.09% (p=0.000) RegexpMatchEasy0_1K 550ns × (0.98,1.01) 530ns × (1.00,1.00) -3.78% (p=0.000) RegexpMatchEasy1_32 135ns × (0.99,1.02) 134ns × (0.99,1.01) -1.33% (p=0.002) RegexpMatchEasy1_1K 879ns × (1.00,1.01) 865ns × (1.00,1.00) -1.58% (p=0.000) RegexpMatchMedium_32 243ns × (1.00,1.00) 233ns × (1.00,1.00) -4.30% (p=0.000) RegexpMatchMedium_1K 70.3µs × (1.00,1.00) 69.5µs × (1.00,1.00) -1.13% (p=0.000) RegexpMatchHard_32 3.82µs × (1.00,1.01) 3.74µs × (1.00,1.00) -1.95% (p=0.000) RegexpMatchHard_1K 117µs × (1.00,1.00) 115µs × (1.00,1.00) -1.69% (p=0.000) Revcomp 917ms × (0.97,1.04) 920ms × (0.97,1.04) ~ (p=0.786) Template 114ms × (0.99,1.01) 117ms × (0.99,1.01) +2.58% (p=0.000) TimeParse 622ns × (0.99,1.01) 615ns × (0.99,1.00) -1.06% (p=0.000) TimeFormat 665ns × (0.99,1.01) 654ns × (0.99,1.00) -1.70% (p=0.000) This CL and previous CL (append) combined: name old mean new mean delta BinaryTree17 5.68s × (0.97,1.04) 5.71s × (0.96,1.05) ~ (p=0.638) Fannkuch11 4.41s × (0.98,1.03) 4.39s × (1.00,1.00) ~ (p=0.474) FmtFprintfEmpty 92.7ns × (0.91,1.16) 82.6ns × (0.98,1.04) -10.89% (p=0.004) FmtFprintfString 281ns × (0.96,1.08) 273ns × (0.98,1.02) ~ (p=0.078) FmtFprintfInt 288ns × (0.97,1.06) 270ns × (0.99,1.01) -6.37% (p=0.000) FmtFprintfIntInt 493ns × (0.97,1.04) 475ns × (0.99,1.01) -3.53% (p=0.002) FmtFprintfPrefixedInt 423ns × (0.97,1.04) 393ns × (1.00,1.01) -7.07% (p=0.000) FmtFprintfFloat 598ns × (0.99,1.01) 574ns × (1.00,1.01) -4.02% (p=0.000) FmtManyArgs 1.89µs × (0.98,1.05) 1.87µs × (0.99,1.02) ~ (p=0.305) GobDecode 14.8ms × (0.98,1.03) 15.0ms × (0.98,1.05) ~ (p=0.237) GobEncode 12.3ms × (0.98,1.01) 11.4ms × (0.99,1.03) -6.95% (p=0.000) Gzip 656ms × (0.99,1.05) 647ms × (0.99,1.01) ~ (p=0.101) Gunzip 142ms × (1.00,1.00) 143ms × (1.00,1.01) +0.58% (p=0.001) HTTPClientServer 91.2µs × (0.97,1.04) 88.5µs × (0.99,1.03) -3.02% (p=0.003) JSONEncode 32.6ms × (0.97,1.08) 29.6ms × (0.98,1.01) -9.10% (p=0.000) JSONDecode 114ms × (0.97,1.05) 104ms × (1.00,1.01) -8.74% (p=0.000) Mandelbrot200 6.11ms × (0.98,1.04) 6.02ms × (1.00,1.00) ~ (p=0.090) GoParse 6.66ms × (0.97,1.04) 6.37ms × (0.97,1.04) -4.41% (p=0.000) RegexpMatchEasy0_32 159ns × (0.99,1.00) 152ns × (0.99,1.01) -4.69% (p=0.000) RegexpMatchEasy0_1K 538ns × (1.00,1.01) 530ns × (1.00,1.00) -1.57% (p=0.000) RegexpMatchEasy1_32 138ns × (1.00,1.00) 134ns × (0.99,1.01) -2.91% (p=0.000) RegexpMatchEasy1_1K 869ns × (0.99,1.01) 865ns × (1.00,1.00) -0.51% (p=0.012) RegexpMatchMedium_32 252ns × (0.99,1.01) 233ns × (1.00,1.00) -7.85% (p=0.000) RegexpMatchMedium_1K 72.7µs × (1.00,1.00) 69.5µs × (1.00,1.00) -4.43% (p=0.000) RegexpMatchHard_32 3.85µs × (1.00,1.00) 3.74µs × (1.00,1.00) -2.74% (p=0.000) RegexpMatchHard_1K 118µs × (1.00,1.00) 115µs × (1.00,1.00) -2.24% (p=0.000) Revcomp 920ms × (0.97,1.07) 920ms × (0.97,1.04) ~ (p=0.998) Template 129ms × (0.98,1.03) 117ms × (0.99,1.01) -9.79% (p=0.000) TimeParse 619ns × (0.99,1.01) 615ns × (0.99,1.00) -0.57% (p=0.011) TimeFormat 661ns × (0.98,1.04) 654ns × (0.99,1.00) ~ (p=0.223) Change-Id: If054d81ab2c71d8d62cf54b5b1fac2af66b387fc Reviewed-on: https://go-review.googlesource.com/9813 Reviewed-by: David Chase <drchase@google.com> Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-05-12cmd/internal/gc: optimize append + write barrierRuss Cox
The code generated for x = append(x, v) is roughly: t := x if len(t)+1 > cap(t) { t = grow(t) } t[len(t)] = v len(t)++ x = t We used to generate this code as Go pseudocode during walk. Generate it instead as actual instructions during gen. Doing so lets us apply a few optimizations. The most important is that when, as in the above example, the source slice and the destination slice are the same, the code can instead do: t := x if len(t)+1 > cap(t) { t = grow(t) x = {base(t), len(t)+1, cap(t)} } else { len(x)++ } t[len(t)] = v That is, in the fast path that does not reallocate the array, only the updated length needs to be written back to x, not the array pointer and not the capacity. This is more like what you'd write by hand in C. It's faster in general, since the fast path elides two of the three stores, but it's especially faster when the form of x is such that the base pointer write would turn into a write barrier. No write, no barrier. name old mean new mean delta BinaryTree17 5.68s × (0.97,1.04) 5.81s × (0.98,1.03) +2.35% (p=0.023) Fannkuch11 4.41s × (0.98,1.03) 4.35s × (1.00,1.00) ~ (p=0.090) FmtFprintfEmpty 92.7ns × (0.91,1.16) 86.0ns × (0.94,1.11) -7.31% (p=0.038) FmtFprintfString 281ns × (0.96,1.08) 276ns × (0.98,1.04) ~ (p=0.219) FmtFprintfInt 288ns × (0.97,1.06) 274ns × (0.98,1.06) -4.94% (p=0.002) FmtFprintfIntInt 493ns × (0.97,1.04) 506ns × (0.99,1.01) +2.65% (p=0.009) FmtFprintfPrefixedInt 423ns × (0.97,1.04) 391ns × (0.99,1.01) -7.52% (p=0.000) FmtFprintfFloat 598ns × (0.99,1.01) 566ns × (0.99,1.01) -5.27% (p=0.000) FmtManyArgs 1.89µs × (0.98,1.05) 1.91µs × (0.99,1.01) ~ (p=0.231) GobDecode 14.8ms × (0.98,1.03) 15.3ms × (0.99,1.02) +3.01% (p=0.000) GobEncode 12.3ms × (0.98,1.01) 11.5ms × (0.97,1.03) -5.93% (p=0.000) Gzip 656ms × (0.99,1.05) 645ms × (0.99,1.01) ~ (p=0.055) Gunzip 142ms × (1.00,1.00) 142ms × (1.00,1.00) -0.32% (p=0.034) HTTPClientServer 91.2µs × (0.97,1.04) 90.5µs × (0.97,1.04) ~ (p=0.468) JSONEncode 32.6ms × (0.97,1.08) 32.0ms × (0.98,1.03) ~ (p=0.190) JSONDecode 114ms × (0.97,1.05) 114ms × (0.99,1.01) ~ (p=0.887) Mandelbrot200 6.11ms × (0.98,1.04) 6.04ms × (1.00,1.01) ~ (p=0.167) GoParse 6.66ms × (0.97,1.04) 6.47ms × (0.97,1.05) -2.81% (p=0.014) RegexpMatchEasy0_32 159ns × (0.99,1.00) 171ns × (0.93,1.07) +7.19% (p=0.002) RegexpMatchEasy0_1K 538ns × (1.00,1.01) 550ns × (0.98,1.01) +2.30% (p=0.000) RegexpMatchEasy1_32 138ns × (1.00,1.00) 135ns × (0.99,1.02) -1.60% (p=0.000) RegexpMatchEasy1_1K 869ns × (0.99,1.01) 879ns × (1.00,1.01) +1.08% (p=0.000) RegexpMatchMedium_32 252ns × (0.99,1.01) 243ns × (1.00,1.00) -3.71% (p=0.000) RegexpMatchMedium_1K 72.7µs × (1.00,1.00) 70.3µs × (1.00,1.00) -3.34% (p=0.000) RegexpMatchHard_32 3.85µs × (1.00,1.00) 3.82µs × (1.00,1.01) -0.81% (p=0.000) RegexpMatchHard_1K 118µs × (1.00,1.00) 117µs × (1.00,1.00) -0.56% (p=0.000) Revcomp 920ms × (0.97,1.07) 917ms × (0.97,1.04) ~ (p=0.808) Template 129ms × (0.98,1.03) 114ms × (0.99,1.01) -12.06% (p=0.000) TimeParse 619ns × (0.99,1.01) 622ns × (0.99,1.01) ~ (p=0.062) TimeFormat 661ns × (0.98,1.04) 665ns × (0.99,1.01) ~ (p=0.524) See next CL for combination with a similar optimization for slice. The benchmarks that are slower in this CL are still faster overall with the combination of the two. Change-Id: I2a7421658091b2488c64741b4db15ab6c3b4cb7e Reviewed-on: https://go-review.googlesource.com/9812 Reviewed-by: David Chase <drchase@google.com>