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Followup to #7458 - Return true for mayPointTo(void[N]) that can hold a slice,

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unless the entire thing is zero
This commit is contained in:
Steven Schveighoffer 2020-04-27 00:25:10 -04:00
parent b1361913bc
commit 2530979868
1 changed files with 34 additions and 16 deletions
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48
std/exception.d
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@ -1196,7 +1196,15 @@ if (__traits(isRef, source) || isDynamicArray!S ||
{ {
static if (is(S == void[n], size_t n)) static if (is(S == void[n], size_t n))
{ {
static if (n >= (void*).sizeof) static if (n >= (void[]).sizeof)
{
// could contain a slice, which could point at anything.
// But a void[N] that is all 0 cannot point anywhere
import std.algorithm.searching : any;
if (__ctfe || any(cast(ubyte[]) source[]))
return true;
}
else static if (n >= (void*).sizeof)
{ {
// Reinterpreting cast is impossible during ctfe // Reinterpreting cast is impossible during ctfe
if (__ctfe) if (__ctfe)
@ -1206,15 +1214,12 @@ if (__traits(isRef, source) || isDynamicArray!S ||
enum al = (void*).alignof - 1; enum al = (void*).alignof - 1;
const base = cast(size_t) &source; const base = cast(size_t) &source;
const alBase = (base + al) & ~al; const alBase = (base + al) & ~al;
const elems = (n - (alBase - base)) / (void*).sizeof;
foreach (const s; (cast(void**) alBase)[0 .. elems]) if ((n - (alBase - base)) >= (void*).sizeof &&
{ mayPointTo(*(cast(void**) alBase), target))
if (mayPointTo(s, target))
return true; return true;
} }
} }
}
else else
{ {
foreach (size_t i; 0 .. S.length) foreach (size_t i; 0 .. S.length)
@ -1473,26 +1478,34 @@ version (StdUnittest)
align((void*).alignof) void[32] voidArr = void; align((void*).alignof) void[32] voidArr = void;
(cast(void*[]) voidArr[])[] = null; // Ensure no false pointers (cast(void*[]) voidArr[])[] = null; // Ensure no false pointers
// zeroed void ranges can't point at anything
assert(!mayPointTo(voidArr, a));
assert(!mayPointTo(voidArr, b));
*cast(void**) &voidArr[16] = &a; // Pointers should be found *cast(void**) &voidArr[16] = &a; // Pointers should be found
alias SA = void[size_t.sizeof + 3];
SA *smallArr1 = cast(SA*)&voidArr;
SA *smallArr2 = cast(SA*)&(voidArr[16]);
// But it should only consider properly aligned pointers // But it should only consider properly aligned pointers
// Write single bytes to avoid issues due to misaligned writes // Write single bytes to avoid issues due to misaligned writes
void*[1] tmp = [&b]; void*[1] tmp = [&b];
(cast(ubyte[]) voidArr[3 .. 3 + (void*).sizeof])[] = cast(ubyte[]) tmp[]; (cast(ubyte[]) voidArr[3 .. 3 + (void*).sizeof])[] = cast(ubyte[]) tmp[];
assert( mayPointTo(voidArr, a)); assert( mayPointTo(*smallArr2, a));
assert(!mayPointTo(voidArr, b)); assert(!mayPointTo(*smallArr1, b));
assert(!doesPointTo(voidArr, a)); // Value might be a false pointer assert(!doesPointTo(voidArr, a)); // Value might be a false pointer
assert(!doesPointTo(voidArr, b)); assert(!doesPointTo(voidArr, b));
auto v2 = cast(void[26]*) &voidArr[3]; // Works for weird sizes/alignments SA *smallArr3 = cast(SA *) &voidArr[13]; // Works for weird sizes/alignments
assert( mayPointTo(*v2, a)); assert( mayPointTo(*smallArr3, a));
assert(!mayPointTo(*v2, b)); assert(!mayPointTo(*smallArr3, b));
assert(!doesPointTo(*v2, a)); assert(!doesPointTo(*smallArr3, a));
assert(!doesPointTo(*v2, b)); assert(!doesPointTo(*smallArr3, b));
auto v3 = cast(void[3]*) &voidArr[16]; // Arrays smaller than pointers are ignored auto v3 = cast(void[3]*) &voidArr[16]; // Arrays smaller than pointers are ignored
assert(!mayPointTo(*v3, a)); assert(!mayPointTo(*v3, a));
@ -1501,10 +1514,15 @@ version (StdUnittest)
assert(!doesPointTo(*v3, a)); assert(!doesPointTo(*v3, a));
assert(!doesPointTo(*v3, b)); assert(!doesPointTo(*v3, b));
assert(mayPointTo(voidArr, a)); // slice-contiaining void[N] might point at anything
assert(mayPointTo(voidArr, b));
static assert(() { static assert(() {
void[16] arr = void; void[16] arr1 = void;
void[size_t.sizeof] arr2 = void;
int var; int var;
return mayPointTo(arr, var) && !doesPointTo(arr, var); return mayPointTo(arr1, var) && !doesPointTo(arr1, var) &&
mayPointTo(arr2, var) && !doesPointTo(arr2, var);
}()); }());
} }