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cmd/compile: learn transitive proofs for safe negative signed adds

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I've split this into it's own CL to make git bisect more effective.

Change-Id: Ib2c6dbc82fb04f50f2d17fbe6626c9fc322fb478
Reviewed-on: https://go-review.googlesource.com/c/go/+/685820
Auto-Submit: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
This commit is contained in:
Jorropo 2025-07-04 09:25:23 +02:00 • committed by Gopher Robot
parent 1a72920f09
commit d574856482
2 changed files with 84 additions and 0 deletions
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14
src/cmd/compile/internal/ssa/prove.go
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@ -2212,6 +2212,20 @@ func addLocalFacts(ft *factsTable, b *Block) {
}
ft.update(b, v, v.Args[0], signed, r)
}
if x.max <= 0 && !signedAddOverflowsOrUnderflows(x.min, y.min, v.Type) {
r := lt
if !x.nonzero() {
r |= eq
}
ft.update(b, v, v.Args[1], signed, r)
}
if y.max <= 0 && !signedAddOverflowsOrUnderflows(x.min, y.min, v.Type) {
r := lt
if !y.nonzero() {
r |= eq
}
ft.update(b, v, v.Args[0], signed, r)
}
case OpAnd64, OpAnd32, OpAnd16, OpAnd8:
ft.update(b, v, v.Args[0], unsigned, lt|eq)
ft.update(b, v, v.Args[1], unsigned, lt|eq)