mirror of
https://github.com/golang/go
synced 2024-11-02 08:01:26 +00:00
034a10d44c
The layout code has to date insisted on stack frames that are 16-aligned including the saved LR, and it ensured this by growing the frame itself. This breaks code that refers to values near the top of the frame by positive offset from SP, and in general it's too magical: if you see TEXT xxx, $N, you expect that the frame size is actually N, not sometimes N and sometimes N+8. This led to a serious bug in the compiler where ambiguously live values were not being zeroed correctly, which in turn triggered an assertion in the GC about finding only valid pointers. The compiler has been fixed to always emit aligned frames, and the hand-written assembly has also been fixed. Now that everything is aligned, make unaligned an error instead of something to "fix" silently. For #9880. Change-Id: I05f01a9df174d64b37fa19b36a6b6c5f18d5ba2d Reviewed-on: https://go-review.googlesource.com/12848 Reviewed-by: Austin Clements <austin@google.com>
360 lines
8.8 KiB
Go
360 lines
8.8 KiB
Go
// +build !nacl
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// run
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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import (
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"bytes"
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"fmt"
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"io/ioutil"
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"log"
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"os"
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"os/exec"
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"path/filepath"
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"regexp"
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"runtime"
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"strconv"
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"strings"
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)
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var tests = `
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# These are test cases for the linker analysis that detects chains of
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# nosplit functions that would cause a stack overflow.
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#
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# Lines beginning with # are comments.
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#
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# Each test case describes a sequence of functions, one per line.
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# Each function definition is the function name, then the frame size,
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# then optionally the keyword 'nosplit', then the body of the function.
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# The body is assembly code, with some shorthands.
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# The shorthand 'call x' stands for CALL x(SB).
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# The shorthand 'callind' stands for 'CALL R0', where R0 is a register.
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# Each test case must define a function named main, and it must be first.
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# That is, a line beginning "main " indicates the start of a new test case.
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# Within a stanza, ; can be used instead of \n to separate lines.
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#
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# After the function definition, the test case ends with an optional
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# REJECT line, specifying the architectures on which the case should
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# be rejected. "REJECT" without any architectures means reject on all architectures.
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# The linker should accept the test case on systems not explicitly rejected.
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#
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# 64-bit systems do not attempt to execute test cases with frame sizes
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# that are only 32-bit aligned.
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# Ordinary function should work
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main 0
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# Large frame marked nosplit is always wrong.
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main 10000 nosplit
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REJECT
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# Calling a large frame is okay.
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main 0 call big
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big 10000
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# But not if the frame is nosplit.
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main 0 call big
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big 10000 nosplit
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REJECT
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# Recursion is okay.
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main 0 call main
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# Recursive nosplit runs out of space.
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main 0 nosplit call main
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REJECT
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# Chains of ordinary functions okay.
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main 0 call f1
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f1 80 call f2
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f2 80
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# Chains of nosplit must fit in the stack limit, 128 bytes.
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main 0 call f1
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f1 80 nosplit call f2
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f2 80 nosplit
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REJECT
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# Larger chains.
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main 0 call f1
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f1 16 call f2
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f2 16 call f3
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f3 16 call f4
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f4 16 call f5
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f5 16 call f6
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f6 16 call f7
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f7 16 call f8
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f8 16 call end
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end 1000
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main 0 call f1
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f1 16 nosplit call f2
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f2 16 nosplit call f3
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f3 16 nosplit call f4
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f4 16 nosplit call f5
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f5 16 nosplit call f6
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f6 16 nosplit call f7
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f7 16 nosplit call f8
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f8 16 nosplit call end
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end 1000
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REJECT
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# Test cases near the 128-byte limit.
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# Ordinary stack split frame is always okay.
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main 112
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main 116
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main 120
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main 124
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main 128
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main 132
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main 136
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# A nosplit leaf can use the whole 128-CallSize bytes available on entry.
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main 112 nosplit
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main 116 nosplit
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main 120 nosplit
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main 124 nosplit
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main 128 nosplit; REJECT
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main 132 nosplit; REJECT
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main 136 nosplit; REJECT
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# Calling a nosplit function from a nosplit function requires
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# having room for the saved caller PC and the called frame.
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# Because ARM doesn't save LR in the leaf, it gets an extra 4 bytes.
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# Because ppc64 doesn't save LR in the leaf, it gets an extra 8 bytes.
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main 112 nosplit call f; f 0 nosplit
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main 116 nosplit call f; f 0 nosplit
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main 120 nosplit call f; f 0 nosplit; REJECT amd64
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main 124 nosplit call f; f 0 nosplit; REJECT amd64 386
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main 128 nosplit call f; f 0 nosplit; REJECT
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main 132 nosplit call f; f 0 nosplit; REJECT
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main 136 nosplit call f; f 0 nosplit; REJECT
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# Calling a splitting function from a nosplit function requires
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# having room for the saved caller PC of the call but also the
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# saved caller PC for the call to morestack.
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# Again the ARM and ppc64 work in less space.
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main 104 nosplit call f; f 0 call f
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main 108 nosplit call f; f 0 call f
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main 112 nosplit call f; f 0 call f; REJECT amd64
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main 116 nosplit call f; f 0 call f; REJECT amd64
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main 120 nosplit call f; f 0 call f; REJECT amd64 386
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main 124 nosplit call f; f 0 call f; REJECT amd64 386
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main 128 nosplit call f; f 0 call f; REJECT
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main 132 nosplit call f; f 0 call f; REJECT
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main 136 nosplit call f; f 0 call f; REJECT
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# Indirect calls are assumed to be splitting functions.
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main 104 nosplit callind
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main 108 nosplit callind
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main 112 nosplit callind; REJECT amd64
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main 116 nosplit callind; REJECT amd64
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main 120 nosplit callind; REJECT amd64 386
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main 124 nosplit callind; REJECT amd64 386
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main 128 nosplit callind; REJECT
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main 132 nosplit callind; REJECT
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main 136 nosplit callind; REJECT
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# Issue 7623
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main 0 call f; f 112
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main 0 call f; f 116
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main 0 call f; f 120
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main 0 call f; f 124
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main 0 call f; f 128
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main 0 call f; f 132
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main 0 call f; f 136
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`
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var (
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commentRE = regexp.MustCompile(`(?m)^#.*`)
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rejectRE = regexp.MustCompile(`(?s)\A(.+?)((\n|; *)REJECT(.*))?\z`)
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lineRE = regexp.MustCompile(`(\w+) (\d+)( nosplit)?(.*)`)
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callRE = regexp.MustCompile(`\bcall (\w+)\b`)
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callindRE = regexp.MustCompile(`\bcallind\b`)
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)
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func main() {
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goarch := os.Getenv("GOARCH")
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if goarch == "" {
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goarch = runtime.GOARCH
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}
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version, err := exec.Command("go", "tool", "compile", "-V").Output()
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if err != nil {
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bug()
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fmt.Printf("running go tool compile -V: %v\n", err)
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return
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}
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if strings.Contains(string(version), "framepointer") {
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// Skip this test if GOEXPERIMENT=framepointer
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return
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}
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dir, err := ioutil.TempDir("", "go-test-nosplit")
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if err != nil {
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bug()
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fmt.Printf("creating temp dir: %v\n", err)
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return
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}
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defer os.RemoveAll(dir)
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tests = strings.Replace(tests, "\t", " ", -1)
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tests = commentRE.ReplaceAllString(tests, "")
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nok := 0
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nfail := 0
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TestCases:
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for len(tests) > 0 {
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var stanza string
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i := strings.Index(tests, "\nmain ")
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if i < 0 {
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stanza, tests = tests, ""
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} else {
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stanza, tests = tests[:i], tests[i+1:]
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}
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m := rejectRE.FindStringSubmatch(stanza)
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if m == nil {
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bug()
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fmt.Printf("invalid stanza:\n\t%s\n", indent(stanza))
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continue
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}
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lines := strings.TrimSpace(m[1])
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reject := false
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if m[2] != "" {
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if strings.TrimSpace(m[4]) == "" {
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reject = true
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} else {
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for _, rej := range strings.Fields(m[4]) {
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if rej == goarch {
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reject = true
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}
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}
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}
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}
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if lines == "" && !reject {
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continue
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}
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var gobuf bytes.Buffer
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fmt.Fprintf(&gobuf, "package main\n")
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var buf bytes.Buffer
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ptrSize := 4
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switch goarch {
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case "ppc64", "ppc64le":
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ptrSize = 8
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fmt.Fprintf(&buf, "#define CALL BL\n#define REGISTER (CTR)\n")
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case "arm":
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fmt.Fprintf(&buf, "#define CALL BL\n#define REGISTER (R0)\n")
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case "arm64":
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ptrSize = 8
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fmt.Fprintf(&buf, "#define CALL BL\n#define REGISTER (R0)\n")
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case "amd64":
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ptrSize = 8
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fmt.Fprintf(&buf, "#define REGISTER AX\n")
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default:
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fmt.Fprintf(&buf, "#define REGISTER AX\n")
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}
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for _, line := range strings.Split(lines, "\n") {
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line = strings.TrimSpace(line)
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if line == "" {
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continue
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}
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for i, subline := range strings.Split(line, ";") {
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subline = strings.TrimSpace(subline)
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if subline == "" {
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continue
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}
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m := lineRE.FindStringSubmatch(subline)
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if m == nil {
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bug()
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fmt.Printf("invalid function line: %s\n", subline)
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continue TestCases
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}
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name := m[1]
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size, _ := strconv.Atoi(m[2])
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// The limit was originally 128 but is now 512.
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// Instead of rewriting the test cases above, adjust
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// the first stack frame to use up the extra bytes.
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if i == 0 {
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size += 512 - 128
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// Noopt builds have a larger stackguard.
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// See ../cmd/dist/buildruntime.go:stackGuardMultiplier
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for _, s := range strings.Split(os.Getenv("GO_GCFLAGS"), " ") {
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if s == "-N" {
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size += 640
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}
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}
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}
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if size%ptrSize == 4 || goarch == "arm64" && size != 0 && (size+8)%16 != 0 {
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continue TestCases
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}
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nosplit := m[3]
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body := m[4]
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if nosplit != "" {
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nosplit = ",7"
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} else {
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nosplit = ",0"
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}
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body = callRE.ReplaceAllString(body, "CALL ·$1(SB);")
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body = callindRE.ReplaceAllString(body, "CALL REGISTER;")
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fmt.Fprintf(&gobuf, "func %s()\n", name)
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fmt.Fprintf(&buf, "TEXT ·%s(SB)%s,$%d-0\n\t%s\n\tRET\n\n", name, nosplit, size, body)
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}
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}
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if err := ioutil.WriteFile(filepath.Join(dir, "asm.s"), buf.Bytes(), 0666); err != nil {
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log.Fatal(err)
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}
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if err := ioutil.WriteFile(filepath.Join(dir, "main.go"), gobuf.Bytes(), 0666); err != nil {
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log.Fatal(err)
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}
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cmd := exec.Command("go", "build")
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cmd.Dir = dir
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output, err := cmd.CombinedOutput()
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if err == nil {
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nok++
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if reject {
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bug()
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fmt.Printf("accepted incorrectly:\n\t%s\n", indent(strings.TrimSpace(stanza)))
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}
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} else {
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nfail++
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if !reject {
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bug()
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fmt.Printf("rejected incorrectly:\n\t%s\n", indent(strings.TrimSpace(stanza)))
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fmt.Printf("\n\tlinker output:\n\t%s\n", indent(string(output)))
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}
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}
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}
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if !bugged && (nok == 0 || nfail == 0) {
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bug()
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fmt.Printf("not enough test cases run\n")
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}
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}
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func indent(s string) string {
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return strings.Replace(s, "\n", "\n\t", -1)
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}
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var bugged = false
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func bug() {
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if !bugged {
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bugged = true
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fmt.Printf("BUG\n")
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}
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}
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