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cmd/compile: don't addLocalInductiveFacts if there is no direct edge from if block to phi block

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Currently in addLocalInductiveFacts, we only check whether
direct edge from if block to phi block exists. If not, the
following logic will treat the phi block as the first successor,
which is wrong.

This patch makes prove pass more conservative, so we disable
some cases in test/prove.go. We will do some optimization in
the following CL and enable these cases then.

Fixes #40367.

Change-Id: I27cf0248f3a82312a6f7dabe11c79a1a34cf5412
Reviewed-on: https://go-review.googlesource.com/c/go/+/244579
Reviewed-by: Zach Jones <zachj1@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Cholerae Hu 2020-07-24 11:00:36 +08:00 • committed by Keith Randall
parent 54e75e8f9d
commit 7f86080476
3 changed files with 53 additions and 2 deletions
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8
src/cmd/compile/internal/ssa/prove.go
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@ -1051,6 +1051,11 @@ func addLocalInductiveFacts(ft *factsTable, b *Block) {
//
// If all of these conditions are true, then i1 < max and i1 >= min.
// To ensure this is a loop header node.
if len(b.Preds) != 2 {
return
}
for _, i1 := range b.Values {
if i1.Op != OpPhi {
continue
@ -1093,6 +1098,9 @@ func addLocalInductiveFacts(ft *factsTable, b *Block) {
}
br = negative
}
if br == unknown {
continue
}
tr, has := domainRelationTable[control.Op]
if !has {