cmd/compile: set conversions to unsafe.Pointer as an escaping operation when -asan is enabled

When ASan is enabled, treat conversions to unsafe.Pointer as
an escaping operation. In this way, all pointer operations on
the stack objects will become operations on the escaped heap
objects. As we've already supported ASan detection of error
memory accesses to heap objects. With this trick, we can use
-asan option to report errors on bad stack operations.

Add test cases.

Updates #44853.

CustomizedGitHooks: yes
Change-Id: I4e7fe46a3ce01f0d219e6a67dc50f4aff7d2ad87
Reviewed-on: https://go-review.googlesource.com/c/go/+/325629
Trust: Fannie Zhang <Fannie.Zhang@arm.com>
Reviewed-by: Keith Randall <khr@golang.org>

2 files changed, 9 insertions, 3 deletions

diff --git a/src/cmd/compile/internal/escape/expr.go b/src/cmd/compile/internal/escape/expr.go
index ced90a47bc..9c3e09d10d 100644
--- a/src/cmd/compile/internal/escape/expr.go
+++ b/src/cmd/compile/internal/escape/expr.go
@@ -100,9 +100,9 @@ func (e *escape) exprSkipInit(k hole, n ir.Node) {
 
 	case ir.OCONV, ir.OCONVNOP:
 		n := n.(*ir.ConvExpr)
-		if ir.ShouldCheckPtr(e.curfn, 2) && n.Type().IsUnsafePtr() && n.X.Type().IsPtr() {
-			// When -d=checkptr=2 is enabled, treat
-			// conversions to unsafe.Pointer as an
+		if (ir.ShouldCheckPtr(e.curfn, 2) || ir.ShouldAsanCheckPtr(e.curfn)) && n.Type().IsUnsafePtr() && n.X.Type().IsPtr() {
+			// When -d=checkptr=2 or -asan is enabled,
+			// treat conversions to unsafe.Pointer as an
 			// escaping operation. This allows better
 			// runtime instrumentation, since we can more
 			// easily detect object boundaries on the heap
diff --git a/src/cmd/compile/internal/ir/expr.go b/src/cmd/compile/internal/ir/expr.go
index 156fe96493..ebb84ad78f 100644
--- a/src/cmd/compile/internal/ir/expr.go
+++ b/src/cmd/compile/internal/ir/expr.go
@@ -1035,6 +1035,12 @@ func ShouldCheckPtr(fn *Func, level int) bool {
 	return base.Debug.Checkptr >= level && fn.Pragma&NoCheckPtr == 0
 }
 
+// ShouldAsanCheckPtr reports whether pointer checking should be enabled for
+// function fn when -asan is enabled.
+func ShouldAsanCheckPtr(fn *Func) bool {
+	return base.Flag.ASan && fn.Pragma&NoCheckPtr == 0
+}
+
 // IsReflectHeaderDataField reports whether l is an expression p.Data
 // where p has type reflect.SliceHeader or reflect.StringHeader.
 func IsReflectHeaderDataField(l Node) bool {