cmd/compile: include callee args section when checking frame too large

The stack frame includes the callee args section. At the point where
we were checking the frame size, that part of the frame had not been
computed yet. Move the check later so we can include the callee args size.

Fixes #20780
Update #25507

Change-Id: Iab97cb89b3a24f8ca19b9123ef2a111d6850c3fe
Reviewed-on: https://go-review.googlesource.com/115195
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

diff --git a/src/cmd/compile/internal/gc/main.go b/src/cmd/compile/internal/gc/main.go
index 74590ccc392644934e52f70fdcef06c3e06b5866..e9d9e5566e6efcedabfddda49950c4854e0ca465 100644 (file)
--- a/src/cmd/compile/internal/gc/main.go
+++ b/src/cmd/compile/internal/gc/main.go
@@ -659,14 +659,6 @@ func Main(archInit func(*Arch)) {
                        Ctxt.DwFixups = nil
                        genDwarfInline = 0
                }
-
-               // Check whether any of the functions we have compiled have gigantic stack frames.
-               obj.SortSlice(largeStackFrames, func(i, j int) bool {
-                       return largeStackFrames[i].Before(largeStackFrames[j])
-               })
-               for _, largePos := range largeStackFrames {
-                       yyerrorl(largePos, "stack frame too large (>1GB)")
-               }
        }
 
        // Phase 9: Check external declarations.
@@ -688,6 +680,14 @@ func Main(archInit func(*Arch)) {
                dumpasmhdr()
        }
 
+       // Check whether any of the functions we have compiled have gigantic stack frames.
+       obj.SortSlice(largeStackFrames, func(i, j int) bool {
+               return largeStackFrames[i].Before(largeStackFrames[j])
+       })
+       for _, largePos := range largeStackFrames {
+               yyerrorl(largePos, "stack frame too large (>1GB)")
+       }
+
        if len(compilequeue) != 0 {
                Fatalf("%d uncompiled functions", len(compilequeue))
        }

diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go
index 8f3947b0a686af8872b154a33ddbe6fed8f42679..cf1164772b0fca519f0c0ed23564bf6f800f574d 100644 (file)
--- a/src/cmd/compile/internal/gc/pgen.go
+++ b/src/cmd/compile/internal/gc/pgen.go
@@ -265,11 +265,24 @@ func compileSSA(fn *Node, worker int) {
                return
        }
        pp := newProgs(fn, worker)
+       defer pp.Free()
        genssa(f, pp)
+       // Check frame size again.
+       // The check above included only the space needed for local variables.
+       // After genssa, the space needed includes local variables and the callee arg region.
+       // We must do this check prior to calling pp.Flush.
+       // If there are any oversized stack frames,
+       // the assembler may emit inscrutable complaints about invalid instructions.
+       if pp.Text.To.Offset >= maxStackSize {
+               largeStackFramesMu.Lock()
+               largeStackFrames = append(largeStackFrames, fn.Pos)
+               largeStackFramesMu.Unlock()
+               return
+       }
+
        pp.Flush() // assemble, fill in boilerplate, etc.
        // fieldtrack must be called after pp.Flush. See issue 20014.
        fieldtrack(pp.Text.From.Sym, fn.Func.FieldTrack)
-       pp.Free()
 }
 
 func init() {

diff --git a/src/go/types/stdlib_test.go b/src/go/types/stdlib_test.go
index dd1510d37e36979e0617479494be65a3f8b8da37..229d2030995b6a270e93e1513ea689a8463853b1 100644 (file)
--- a/src/go/types/stdlib_test.go
+++ b/src/go/types/stdlib_test.go
@@ -175,6 +175,7 @@ func TestStdFixed(t *testing.T) {
                "issue22200.go",  // go/types does not have constraints on stack size
                "issue22200b.go", // go/types does not have constraints on stack size
                "issue25507.go",  // go/types does not have constraints on stack size
+               "issue20780.go",  // go/types does not have constraints on stack size
        )
 }
 

diff --git a/test/fixedbugs/issue20780.go b/test/fixedbugs/issue20780.go
new file mode 100644 (file)
index 0000000..a31e031
--- /dev/null
+++ b/test/fixedbugs/issue20780.go
@@ -0,0 +1,20 @@
+// errorcheck
+
+// Copyright 2018 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.
+
+// We have a limit of 1GB for stack frames.
+// Make sure we include the callee args section.
+// (The dispatch wrapper which implements (*S).f
+// copies the return value from f to a stack temp, then
+// from that stack temp to the return value of (*S).f.
+// It uses ~800MB for each section.)
+
+package main
+
+type S struct {
+       i interface {
+               f() [800e6]byte
+       }
+}