cmd/compile: don't generate liveness maps when the stack is too large

Fixes #20529

Change-Id: I3cb0c037b1737fbc3fa3b1b61ed8a42cfaf8e10d
Reviewed-on: https://go-review.googlesource.com/44344
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go
index 427146ffb0bc60be534cd360076a07828e304980..66e4a10ee88f32b339652621e0e50e8f44cf4b99 100644 (file)
--- a/src/cmd/compile/internal/gc/pgen.go
+++ b/src/cmd/compile/internal/gc/pgen.go
@@ -230,6 +230,8 @@ func compilenow() bool {
        return nBackendWorkers == 1 && Debug_compilelater == 0
 }
 
+const maxStackSize = 1 << 31
+
 // compileSSA builds an SSA backend function,
 // uses it to generate a plist,
 // and flushes that plist to machine code.
@@ -238,7 +240,7 @@ func compileSSA(fn *Node, worker int) {
        ssafn := buildssa(fn, worker)
        pp := newProgs(fn, worker)
        genssa(ssafn, pp)
-       if pp.Text.To.Offset < 1<<31 {
+       if pp.Text.To.Offset < maxStackSize {
                pp.Flush()
        } else {
                largeStackFramesMu.Lock()

diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 94c1bd57066ecb9870a2aa6e5babe0d2eb200949..1497c5c2f5f2dcf3ec9201aeb0f38e3a49536ba2 100644 (file)
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -4373,8 +4373,11 @@ func genssa(f *ssa.Func, pp *Progs) {
 
        e := f.Frontend().(*ssafn)
 
-       // Generate GC bitmaps.
-       s.stackMapIndex = liveness(e, f)
+       // Generate GC bitmaps, except if the stack is too large,
+       // in which compilation will fail later anyway (issue 20529).
+       if e.stksize < maxStackSize {
+               s.stackMapIndex = liveness(e, f)
+       }
 
        // Remember where each block starts.
        s.bstart = make([]*obj.Prog, f.NumBlocks())

diff --git a/src/go/types/stdlib_test.go b/src/go/types/stdlib_test.go
index 3f02dd98baf3e4ca5c694aaa895edcd3409e3dac..b9a6681e66aae11f65a33b73b10972f6fe4d7b9c 100644 (file)
--- a/src/go/types/stdlib_test.go
+++ b/src/go/types/stdlib_test.go
@@ -172,6 +172,7 @@ func TestStdFixed(t *testing.T) {
                "issue18882.go", // go/types doesn't check validity of //go:xxx directives
                "issue20232.go", // go/types handles larger constants than gc
                "issue20227.go", // go/types does not handle this yet
+               "issue20529.go", // go/types does not have constraints on stack size
        )
 }
 

diff --git a/test/fixedbugs/issue20529.go b/test/fixedbugs/issue20529.go
new file mode 100644 (file)
index 0000000..cd0c23d
--- /dev/null
+++ b/test/fixedbugs/issue20529.go
@@ -0,0 +1,18 @@
+// errorcheck
+
+// +build amd64
+
+// Copyright 2017 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.
+
+// Issue 20529: Large stack frames caused compiler panics.
+// Only tested on amd64 because the test only makes sense
+// on a 64 bit system, and it is platform-agnostic,
+// so testing one suffices.
+
+package p
+
+func f() { // ERROR "stack frame too large"
+       _ = [][]int{1e9: []int{}}
+}