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628674a0c1
ScoreInductionInc was introduced in 19f05770b0.
The goal was to keep the i++ in-place in a register.
Placing ScoreInductionInc later than ScoreFlags further improves
the generated code, mainly for code involving carry chains.
For example, the math/big.addVW_ref inner loop was:
LEAQ 1(CX), R8
ADDQ DX, R9
MOVQ R9, (AX)(CX*8)
SBBQ R9, R9
NEGQ R9
MOVQ R8, CX
After this commit:
ADDQ DX, R9
MOVQ R9, (AX)(CX*8)
SBBQ R9, R9
NEGQ R9
INCQ CX
This is almost uniformly an improvement, across GOARCHes.
There are a few functions where this perturbs regalloc and causes
a little bit of movement, but they are rare and appear to be the
usual uninteresting regalloc change noise.
Change-Id: I883a92e4511136f478cf49471ba8b628434393dc
Reviewed-on: https://go-review.googlesource.com/c/go/+/773660
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Keith Randall <khr@golang.org>
33 lines
709 B
Go
33 lines
709 B
Go
// asmcheck
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// Copyright 2025 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package codegen
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import "math/bits"
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func f(n int) int {
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r := 0
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// arm64:-"MOVD R[0-9]+, R[0-9]+"
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// amd64:-"LEAQ" "INCQ"
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for i := range n {
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r += i
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}
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return r
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}
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// addVW has loop body with both a flag-producing op and an induction-variable increment.
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// It ensures that the induction increment doesn't get pointlessly spilled.
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func addVWLike(z, x []uint, y uint) uint {
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c := y
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// arm64:-"MOVD R[0-9]+, R[0-9]+"
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// amd64:-"LEAQ" "INCQ"
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for i := range z {
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zi, cc := bits.Add(x[i], c, 0)
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z[i] = zi
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c = cc
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}
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return c
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}
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