From 8628bf9a972993bdb978b7d6fa7a6bb1ca2cddbe Mon Sep 17 00:00:00 2001 From: Cherry Zhang Date: Fri, 12 Mar 2021 18:38:02 -0500 Subject: cmd/compile: resurrect clobberdead mode This CL resurrects the clobberdead debugging mode (CL 23924). When -clobberdead flag is set (TODO: make it GOEXPERIMENT?), the compiler inserts code that clobbers all dead stack slots that contains pointers. Mark windows syscall functions cgo_unsafe_args, as the code actually does that, by taking the address of one argument and passing it to cgocall. Change-Id: Ie09a015f4bd14ae6053cc707866e30ae509b9d6f Reviewed-on: https://go-review.googlesource.com/c/go/+/301791 Trust: Cherry Zhang Run-TryBot: Cherry Zhang TryBot-Result: Go Bot Reviewed-by: David Chase Reviewed-by: Than McIntosh --- test/codegen/clobberdead.go | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) create mode 100644 test/codegen/clobberdead.go (limited to 'test/codegen') diff --git a/test/codegen/clobberdead.go b/test/codegen/clobberdead.go new file mode 100644 index 0000000000..f8d964cba6 --- /dev/null +++ b/test/codegen/clobberdead.go @@ -0,0 +1,32 @@ +// asmcheck -gcflags=-clobberdead + +// +build amd64 + +// Copyright 2021 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 + +type T [2]*int // contain pointer, not SSA-able (so locals are not registerized) + +var p1, p2, p3 T + +func F() { + // 3735936685 is 0xdeaddead + // clobber x, y at entry. not clobber z (stack object). + // amd64:`MOVL\t\$3735936685, ""\.x`, `MOVL\t\$3735936685, ""\.y`, -`MOVL\t\$3735936685, ""\.z` + x, y, z := p1, p2, p3 + addrTaken(&z) + // x is dead at the call (the value of x is loaded before the CALL), y is not + // amd64:`MOVL\t\$3735936685, ""\.x`, -`MOVL\t\$3735936685, ""\.y` + use(x) + // amd64:`MOVL\t\$3735936685, ""\.x`, `MOVL\t\$3735936685, ""\.y` + use(y) +} + +//go:noinline +func use(T) {} + +//go:noinline +func addrTaken(*T) {} -- cgit v1.3