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[clang][Interp] Fix variables referring to their own address (#70587)

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This was a combination of issues:
  1) We can subtract pointers that don't point into arrays.
  2) In C, everything is possible.
This commit is contained in:
Timm Baeder
2023-11-15 08:03:06 +01:00
committed by GitHub
parent 51c351f49e
commit e2f8ec7255
3 changed files with 21 additions and 2 deletions
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4
clang/lib/AST/Interp/Interp.h
View File

@@ -1453,7 +1453,7 @@ bool OffsetHelper(InterpState &S, CodePtr OpPC, const T &Offset,
DiagInvalidOffset();
}
if (Invalid && !Ptr.isDummy())
if (Invalid && !Ptr.isDummy() && S.getLangOpts().CPlusPlus)
return false;
// Offset is valid - compute it on unsigned.
@@ -1531,7 +1531,7 @@ inline bool SubPtr(InterpState &S, CodePtr OpPC) {
const Pointer &LHS = S.Stk.pop<Pointer>();
const Pointer &RHS = S.Stk.pop<Pointer>();
if (!Pointer::hasSameArray(LHS, RHS)) {
if (!Pointer::hasSameBase(LHS, RHS) && S.getLangOpts().CPlusPlus) {
// TODO: Diagnose.
return false;
}

4
clang/test/AST/Interp/c.c
View File

@@ -4,6 +4,7 @@
// RUN: %clang_cc1 -pedantic -verify=pedantic-ref -std=c11 %s
typedef __INTPTR_TYPE__ intptr_t;
typedef __PTRDIFF_TYPE__ ptrdiff_t;
_Static_assert(1, "");
_Static_assert(0 != 1, "");
@@ -81,3 +82,6 @@ const intptr_t L = (intptr_t)(&(yy->y)); // expected-error {{not a compile-time
// pedantic-expected-error {{not a compile-time constant}} \
// ref-error {{not a compile-time constant}} \
// pedantic-ref-error {{not a compile-time constant}}
const ptrdiff_t m = &m + 137 - &m;
_Static_assert(m == 137, ""); // pedantic-ref-warning {{GNU extension}} \
// pedantic-expected-warning {{GNU extension}}

15
clang/test/AST/Interp/literals.cpp
View File

@@ -7,6 +7,7 @@
#define INT_MAX __INT_MAX__
typedef __INTPTR_TYPE__ intptr_t;
typedef __PTRDIFF_TYPE__ ptrdiff_t;
static_assert(true, "");
@@ -198,6 +199,20 @@ namespace PointerComparison {
// ref-note {{comparison between '&s.b' and 'nullptr' has unspecified value}}
constexpr bool v7 = qv <= (void*)&s.b; // ok
constexpr ptrdiff_t m = &m - &m;
static_assert(m == 0, "");
constexpr ptrdiff_t m2 = (&m2 + 1) - (&m2 + 1);
static_assert(m2 == 0, "");
constexpr long m3 = (&m3 + 1) - (&m3);
static_assert(m3 == 1, "");
constexpr long m4 = &m4 + 2 - &m4; // ref-error {{must be initialized by a constant expression}} \
// ref-note {{cannot refer to element 2 of non-array object}} \
// expected-error {{must be initialized by a constant expression}} \
// expected-note {{cannot refer to element 2 of non-array object}}
}
namespace SizeOf {