cmd/compile: always mark atColumn1 results as statements

In 31618, we end up comparing the is-stmt-ness of positions
to repurpose real instructions as inline marks. If the is-stmt-ness
doesn't match, we end up not being able to remove the inline mark.

Always use statement-full positions to do the matching, so we
always find a match if there is one.

Also always use positions that are statements for inline marks.

Fixes #31618

Change-Id: Idaf39bdb32fa45238d5cd52973cadf4504f947d5
Reviewed-on: https://go-review.googlesource.com/c/go/+/173324
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

3 files changed, 3 insertions, 2 deletions

diff --git a/src/cmd/compile/internal/gc/inl.go b/src/cmd/compile/internal/gc/inl.go
index 35cbadafd7..5013c55663 100644
--- a/src/cmd/compile/internal/gc/inl.go
+++ b/src/cmd/compile/internal/gc/inl.go
@@ -1055,7 +1055,7 @@ func mkinlcall(n, fn *Node, maxCost int32) *Node {
 	// to put a breakpoint. Not sure if that's really necessary or not
 	// (in which case it could go at the end of the function instead).
 	inlMark := nod(OINLMARK, nil, nil)
-	inlMark.Pos = n.Pos.WithDefaultStmt()
+	inlMark.Pos = n.Pos.WithIsStmt()
 	inlMark.Xoffset = int64(newIndex)
 	ninit.Append(inlMark)
 
diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 930779045a..0f043d8b5e 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -5369,6 +5369,7 @@ func genssa(f *ssa.Func, pp *Progs) {
 				// We found an instruction with the same source position as
 				// some of the inline marks.
 				// Use this instruction instead.
+				p.Pos = p.Pos.WithIsStmt() // promote position to a statement
 				pp.curfn.Func.lsym.Func.AddInlMark(p, inlMarks[m])
 				// Make the inline mark a real nop, so it doesn't generate any code.
 				m.As = obj.ANOP
diff --git a/src/cmd/internal/src/pos.go b/src/cmd/internal/src/pos.go
index 0e8973fe90..c9d3d347db 100644
--- a/src/cmd/internal/src/pos.go
+++ b/src/cmd/internal/src/pos.go
@@ -445,5 +445,5 @@ func (x lico) lineNumberHTML() string {
 }
 
 func (x lico) atColumn1() lico {
-	return makeLico(x.Line(), 1) | (x & (isStmtMask | xlogueMask))
+	return makeLico(x.Line(), 1).withIsStmt()
 }