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author | Giovanni Bajo <rasky@develer.com> | 2019-09-16 10:25:48 +0200 |
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committer | Giovanni Bajo <rasky@develer.com> | 2019-09-26 18:47:12 +0000 |
commit | 1658263bbfbf0c31f179df878049e6d4690501c8 (patch) | |
tree | d0acf2fa6bceb0d71c79dccec3048d9c7e0f36dd /test/loopbce.go | |
parent | 9740b60e140433c6ab2230ca4f53935818221445 (diff) | |
download | go-1658263bbfbf0c31f179df878049e6d4690501c8.tar.gz go-1658263bbfbf0c31f179df878049e6d4690501c8.zip |
cmd/compile: detect indvars that are bound by other indvars
prove wasn't able to detect induction variables that was bound
by another inducation variable. This happened because an indvar
is a Phi, and thus in case of a dependency, the loop bounding
condition looked as Phi < Phi. This triggered an existing
codepath that checked whether the upper bound was a Phi to
detect loop conditions written in reversed order respect to the
idiomatic way (eg: for i:=0; len(n)>i; i++).
To fix this, we call the indvar pattern matching on both operands
of the loop condition, so that the first operand that matches
will be treated as the indvar.
Updates #24660 (removes a boundcheck from Fannkuch)
Change-Id: Iade83d8deb54f14277ed3f2e37b190e1ed173d11
Reviewed-on: https://go-review.googlesource.com/c/go/+/195220
Reviewed-by: David Chase <drchase@google.com>
Diffstat (limited to 'test/loopbce.go')
-rw-r--r-- | test/loopbce.go | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/test/loopbce.go b/test/loopbce.go index e0a6463c5e..f0c9bd0f81 100644 --- a/test/loopbce.go +++ b/test/loopbce.go @@ -257,6 +257,39 @@ func k5(a [100]int) [100]int { return a } +func d1(a [100]int) [100]int { + for i := 0; i < 100; i++ { // ERROR "Induction variable: limits \[0,100\), increment 1$" + for j := 0; j < i; j++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$" + a[j] = 0 // ERROR "Proved IsInBounds$" + a[j+1] = 0 // FIXME: this boundcheck should be eliminated + a[j+2] = 0 + } + } + return a +} + +func d2(a [100]int) [100]int { + for i := 0; i < 100; i++ { // ERROR "Induction variable: limits \[0,100\), increment 1$" + for j := 0; i > j; j++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$" + a[j] = 0 // ERROR "Proved IsInBounds$" + a[j+1] = 0 // FIXME: this boundcheck should be eliminated + a[j+2] = 0 + } + } + return a +} + +func d3(a [100]int) [100]int { + for i := 0; i <= 99; i++ { // ERROR "Induction variable: limits \[0,99\], increment 1$" + for j := 0; j <= i-1; j++ { // ERROR "Induction variable: limits \[0,\?\], increment 1$" + a[j] = 0 // ERROR "Proved IsInBounds$" + a[j+1] = 0 // ERROR "Proved IsInBounds$" + a[j+2] = 0 + } + } + return a +} + func nobce1() { // tests overflow of max-min a := int64(9223372036854774057) |