cmd/compile: clarify division bounds check optimization

The name of the function should mention division.
Eliminate double negatives from the comment describing it.

Change-Id: Icef1a5139b3a91b86acb930af97938f5160f7342
Reviewed-on: https://go-review.googlesource.com/c/go/+/217001
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

1 files changed, 5 insertions, 3 deletions

diff --git a/src/cmd/compile/internal/ssa/prove.go b/src/cmd/compile/internal/ssa/prove.go
index 774fa94dbc..01825579d9 100644
--- a/src/cmd/compile/internal/ssa/prove.go
+++ b/src/cmd/compile/internal/ssa/prove.go
@@ -1243,9 +1243,11 @@ func simplifyBlock(sdom SparseTree, ft *factsTable, b *Block) {
 			divdLim, divdLimok := ft.limits[divd.ID]
 			if (divrLimok && (divrLim.max < -1 || divrLim.min > -1)) ||
 				(divdLimok && divdLim.min > mostNegativeDividend[v.Op]) {
-				v.AuxInt = 1 // see NeedsFixUp in genericOps - v.AuxInt = 0 means we have not proved
-				// that the divisor is not -1 and the dividend is not the most negative,
-				// so we need to add fix-up code.
+				// See DivisionNeedsFixUp in rewrite.go.
+				// v.AuxInt = 1 means we have proved both that the divisor is not -1
+				// and that the dividend is not the most negative integer,
+				// so we do not need to add fix-up code.
+				v.AuxInt = 1
 				if b.Func.pass.debug > 0 {
 					b.Func.Warnl(v.Pos, "Proved %v does not need fix-up", v.Op)
 				}