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cmd/cgo: use C exact-width integer types to represent Go types

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The exact-width integer types are required to use two’s complement
representation and may not have padding bits, cf. §7.20.1.1/1 in the C11
standard or https://en.cppreference.com/w/c/types/integer.  This ensures that
they have the same domain and representation as the corresponding Go types.

Fixes #29878

Change-Id: Ie8a51e91666dfd89731c7859abe47356c94ca1be
GitHub-Last-Rev: 546a2cc3f1
GitHub-Pull-Request: golang/go#29907
Reviewed-on: https://go-review.googlesource.com/c/go/+/159258
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Philipp Stephani 2019-03-18 20:13:17 +00:00 • committed by Ian Lance Taylor
parent 7b916243d9
commit 08751259b7
6 changed files with 89 additions and 22 deletions
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38
src/cmd/cgo/gcc.go
View file

@ -23,6 +23,7 @@ import (
"internal/xcoff"
"math"
"os"
"regexp"
"strconv"
"strings"
"unicode"
@ -2046,6 +2047,8 @@ type typeConv struct {
ptrSize int64
intSize int64
exactWidthIntegerTypes map[string]*Type
}
var tagGen int
@ -2088,6 +2091,21 @@ func (c *typeConv) Init(ptrSize, intSize int64) {
} else {
c.goVoidPtr = c.Ident("unsafe.Pointer")
}
c.exactWidthIntegerTypes = make(map[string]*Type)
for _, t := range []ast.Expr{
c.int8, c.int16, c.int32, c.int64,
c.uint8, c.uint16, c.uint32, c.uint64,
} {
name := t.(*ast.Ident).Name
u := new(Type)
*u = *goTypes[name]
if u.Align > ptrSize {
u.Align = ptrSize
}
u.Go = t
c.exactWidthIntegerTypes[name] = u
}
}
// base strips away qualifiers and typedefs to get the underlying type
@ -2459,6 +2477,24 @@ func (c *typeConv) Type(dtype dwarf.Type, pos token.Pos) *Type {
t.Align = c.ptrSize
break
}
// Exact-width integer types. These are always compatible with
// the corresponding Go types since the C standard requires
// them to have no padding bit and use the two’s complement
// representation.
if exactWidthIntegerType.MatchString(dt.Name) {
sub := c.Type(dt.Type, pos)
u := c.exactWidthIntegerTypes[strings.TrimSuffix(dt.Name, "_t")]
if sub.Size != u.Size {
fatalf("%s: unexpected size: %d vs. %d – %s", lineno(pos), sub.Size, u.Size, dtype)
}
if sub.Align != u.Align {
fatalf("%s: unexpected alignment: %d vs. %d – %s", lineno(pos), sub.Align, u.Align, dtype)
}
t.Size = u.Size
t.Align = u.Align
t.Go = u.Go
break
}
name := c.Ident("_Ctype_" + dt.Name)
goIdent[name.Name] = name
sub := c.Type(dt.Type, pos)
@ -2594,6 +2630,8 @@ func (c *typeConv) Type(dtype dwarf.Type, pos token.Pos) *Type {
return t
}
var exactWidthIntegerType = regexp.MustCompile(`^u?int(8|16|32|64)_t$`)
// isStructUnionClass reports whether the type described by the Go syntax x
// is a struct, union, or class with a tag.
func isStructUnionClass(x ast.Expr) bool {