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go/test/fixedbugs/issue15585.go
David Chase 3c09001917 cmd/compile: correct sparseSet probes in regalloc to avoid index error
In regalloc, a sparse map is preallocated for later use by
spill-in-loop sinking.  However, variables (spills) are added
during register allocation before spill sinking, and a map
query involving any of these new variables will index out of
bounds in the map.

To fix:
1) fix the queries to use s.orig[v.ID].ID instead, to ensure
proper indexing.  Note that s.orig will be nil for values
that are not eligible for spilling (like memory and flags).

2) add a test.

Fixes #15585.

Change-Id: I8f2caa93b132a0f2a9161d2178320d5550583075
Reviewed-on: https://go-review.googlesource.com/22911
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-05-09 18:35:44 +00:00

46 lines
829 B
Go

// compile
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package bug
func example(n int) (rc int) {
var cc, ll, pp, rr [27]int
for q0 := 0; q0 < n-2; q0++ {
for q1 := q0 + 2; q1 < n; q1++ {
var c, d, l, p, r int
b0 := 1 << uint(q0)
b1 := 1 << uint(q1)
l = ((b0 << 1) | b1) << 1
c = b0 | b1 | (-1 << uint(n))
r = ((b0 >> 1) | b1) >> 1
E:
if c != -1 {
p = ^(l | c | r)
} else {
rc++
goto R
}
L:
if p != 0 {
lsb := p & -p
p &^= lsb
ll[d], cc[d], rr[d], pp[d] = l, c, r, p
l, c, r = (l|lsb)<<1, c|lsb, (r|lsb)>>1
d++
goto E
}
R:
d--
if d >= 0 {
l, c, r, p = ll[d], cc[d], rr[d], pp[d]
goto L
}
}
}
rc <<= 1
return
}