cmd/compile: handle new panicindex/slice names in optimizations

These new calls should not prevent NOSPLIT promotion, like the old ones.
These new calls should not prevent racefuncenter/exit removal.

(The latter was already true, as the new calls are not yet lowered
to StaticCalls at the point where racefuncenter/exit removal is done.)

Add tests to make sure we don't regress (again).

Fixes #31219

Change-Id: I3fb6b17cdd32c425829f1e2498defa813a5a9ace
Reviewed-on: https://go-review.googlesource.com/c/go/+/170639
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>

2 files changed, 31 insertions, 0 deletions

diff --git a/test/codegen/race.go b/test/codegen/race.go
new file mode 100644
index 0000000000..ed6706f880
--- /dev/null
+++ b/test/codegen/race.go
@@ -0,0 +1,20 @@
+// asmcheck -race
+
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package codegen
+
+// Check that we elide racefuncenter/racefuncexit for
+// functions with no calls (but which might panic
+// in various ways). See issue 31219.
+// amd64:-"CALL.*racefuncenter.*"
+func RaceMightPanic(a []int, i, j, k, s int) {
+	var b [4]int
+	_ = b[i]     // panicIndex
+	_ = a[i:j]   // panicSlice
+	_ = a[i:j:k] // also panicSlice
+	_ = i << s   // panicShift
+	_ = i / j    // panicDivide
+}
diff --git a/test/codegen/stack.go b/test/codegen/stack.go
index ed2c1ed959..ca37622286 100644
--- a/test/codegen/stack.go
+++ b/test/codegen/stack.go
@@ -98,3 +98,14 @@ func check_asmout(a, b int) int {
 	// arm:`.*b\+4\(FP\)`
 	return b
 }
+
+// Check that simple functions get promoted to nosplit, even when
+// they might panic in various ways. See issue 31219.
+// amd64:"TEXT\t.*NOSPLIT.*"
+func MightPanic(a []int, i, j, k, s int) {
+	_ = a[i]     // panicIndex
+	_ = a[i:j]   // panicSlice
+	_ = a[i:j:k] // also panicSlice
+	_ = i << s   // panicShift
+	_ = i / j    // panicDivide
+}