PR28739: Check that integer values fit into 64 bits before extracting them as 64 bit values for pointer arithmetic.
This fixes various ways to tickle an assertion in constant expression
evaluation when using __int128. Longer term, we need to figure out what should
happen here: either any kind of overflow in offset calculation should result in
a non-constant value or we should truncate to 64 bits. In C++11 onwards, we're
effectively already checking for overflow because we strictly enforce array
bounds checks, but even there some forms of overflow can slip past undetected.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@293568 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 92c8107..f2e7628 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -1460,9 +1460,17 @@
/// Sign- or zero-extend a value to 64 bits. If it's already 64 bits, just
/// return its existing value.
-static int64_t getExtValue(const APSInt &Value) {
- return Value.isSigned() ? Value.getSExtValue()
- : static_cast<int64_t>(Value.getZExtValue());
+static bool getExtValue(EvalInfo &Info, const Expr *E, const APSInt &Value,
+ int64_t &Result) {
+ if (Value.isSigned() ? Value.getMinSignedBits() > 64
+ : Value.getActiveBits() > 64) {
+ Info.FFDiag(E);
+ return false;
+ }
+
+ Result = Value.isSigned() ? Value.getSExtValue()
+ : static_cast<int64_t>(Value.getZExtValue());
+ return true;
}
/// Should this call expression be treated as a string literal?
@@ -3184,7 +3192,9 @@
return false;
}
- int64_t Offset = getExtValue(RHS.getInt());
+ int64_t Offset;
+ if (!getExtValue(Info, E, RHS.getInt(), Offset))
+ return false;
if (Opcode == BO_Sub)
Offset = -Offset;
@@ -5148,8 +5158,10 @@
if (!EvaluateInteger(E->getIdx(), Index, Info))
return false;
- return HandleLValueArrayAdjustment(Info, E, Result, E->getType(),
- getExtValue(Index));
+ int64_t Offset;
+ if (!getExtValue(Info, E, Index, Offset))
+ return false;
+ return HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Offset);
}
bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) {
@@ -5415,7 +5427,9 @@
if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK)
return false;
- int64_t AdditionalOffset = getExtValue(Offset);
+ int64_t AdditionalOffset;
+ if (!getExtValue(Info, E, Offset, AdditionalOffset))
+ return false;
if (E->getOpcode() == BO_Sub)
AdditionalOffset = -AdditionalOffset;
@@ -5614,14 +5628,14 @@
APSInt Alignment;
if (!EvaluateInteger(E->getArg(1), Alignment, Info))
return false;
- CharUnits Align = CharUnits::fromQuantity(getExtValue(Alignment));
+ CharUnits Align = CharUnits::fromQuantity(Alignment.getZExtValue());
if (E->getNumArgs() > 2) {
APSInt Offset;
if (!EvaluateInteger(E->getArg(2), Offset, Info))
return false;
- int64_t AdditionalOffset = -getExtValue(Offset);
+ int64_t AdditionalOffset = -Offset.getZExtValue();
OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset);
}
@@ -5638,12 +5652,11 @@
if (BaseAlignment < Align) {
Result.Designator.setInvalid();
- // FIXME: Quantities here cast to integers because the plural modifier
- // does not work on APSInts yet.
+ // FIXME: Add support to Diagnostic for long / long long.
CCEDiag(E->getArg(0),
diag::note_constexpr_baa_insufficient_alignment) << 0
- << (int) BaseAlignment.getQuantity()
- << (unsigned) getExtValue(Alignment);
+ << (unsigned)BaseAlignment.getQuantity()
+ << (unsigned)Align.getQuantity();
return false;
}
}
@@ -5651,18 +5664,14 @@
// The offset must also have the correct alignment.
if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) {
Result.Designator.setInvalid();
- APSInt Offset(64, false);
- Offset = OffsetResult.Offset.getQuantity();
- if (OffsetResult.Base)
- CCEDiag(E->getArg(0),
- diag::note_constexpr_baa_insufficient_alignment) << 1
- << (int) getExtValue(Offset) << (unsigned) getExtValue(Alignment);
- else
- CCEDiag(E->getArg(0),
- diag::note_constexpr_baa_value_insufficient_alignment)
- << Offset << (unsigned) getExtValue(Alignment);
-
+ (OffsetResult.Base
+ ? CCEDiag(E->getArg(0),
+ diag::note_constexpr_baa_insufficient_alignment) << 1
+ : CCEDiag(E->getArg(0),
+ diag::note_constexpr_baa_value_insufficient_alignment))
+ << (int)OffsetResult.Offset.getQuantity()
+ << (unsigned)Align.getQuantity();
return false;
}
@@ -7968,12 +7977,13 @@
// Handle cases like (unsigned long)&a + 4.
if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) {
Result = LHSVal;
- CharUnits AdditionalOffset =
- CharUnits::fromQuantity(RHSVal.getInt().getZExtValue());
+ int64_t Offset;
+ if (!getExtValue(Info, E, RHSVal.getInt(), Offset))
+ return false;
if (E->getOpcode() == BO_Add)
- Result.getLValueOffset() += AdditionalOffset;
+ Result.getLValueOffset() += CharUnits::fromQuantity(Offset);
else
- Result.getLValueOffset() -= AdditionalOffset;
+ Result.getLValueOffset() -= CharUnits::fromQuantity(Offset);
return true;
}
@@ -7981,8 +7991,10 @@
if (E->getOpcode() == BO_Add &&
RHSVal.isLValue() && LHSVal.isInt()) {
Result = RHSVal;
- Result.getLValueOffset() +=
- CharUnits::fromQuantity(LHSVal.getInt().getZExtValue());
+ int64_t Offset;
+ if (!getExtValue(Info, E, LHSVal.getInt(), Offset))
+ return false;
+ Result.getLValueOffset() += CharUnits::fromQuantity(Offset);
return true;
}
diff --git a/test/Sema/const-eval.c b/test/Sema/const-eval.c
index bfb58bc..8a8e6fd 100644
--- a/test/Sema/const-eval.c
+++ b/test/Sema/const-eval.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -triple i686-linux %s -Wno-tautological-pointer-compare
+// RUN: %clang_cc1 -fsyntax-only -verify -triple x86_64-linux %s -Wno-tautological-pointer-compare
#define EVAL_EXPR(testno, expr) int test##testno = sizeof(struct{char qq[expr];});
int x;
@@ -126,7 +126,7 @@
EVAL_EXPR(49, &x < &x - 100 ? 1 : -1) // expected-error {{must have a constant size}}
extern struct Test50S Test50;
-EVAL_EXPR(50, &Test50 < (struct Test50S*)((unsigned)&Test50 + 10)) // expected-error {{must have a constant size}}
+EVAL_EXPR(50, &Test50 < (struct Test50S*)((unsigned long)&Test50 + 10)) // expected-error {{must have a constant size}}
// <rdar://problem/11874571>
EVAL_EXPR(51, 0 != (float)1e99)
@@ -137,3 +137,15 @@
void PR24622();
struct PR24622 {} pr24622;
EVAL_EXPR(52, &pr24622 == (void *)&PR24622); // expected-error {{must have a constant size}}
+
+// Reject cases that would require more than 64 bits of pointer offset to
+// represent.
+// FIXME: We don't check for all offset overflow, just immediate adjustments
+// that don't fit in 64 bits. We should consistently either check all offset
+// adjustments or truncate to 64 bits everywhere.
+void *PR28739a = (__int128)(unsigned long)-1 + &PR28739a; // expected-error {{not a compile-time constant}}
+void *PR28739b = &PR28739b + (__int128)(unsigned long)-1; // expected-error {{not a compile-time constant}}
+__int128 PR28739c = (&PR28739c + (__int128)(unsigned long)-1) - &PR28739c; // expected-error {{not a compile-time constant}}
+void *PR28739d = &(&PR28739d)[(__int128)(unsigned long)-1]; // expected-error {{not a compile-time constant}}
+__int128 PR28739e = (__int128)(unsigned long)-1 + (long)&PR28739e; // expected-error {{not a compile-time constant}}
+__int128 PR28739f = (long)&PR28739f + (__int128)(unsigned long)-1; // expected-error {{not a compile-time constant}}
diff --git a/test/SemaCXX/constant-expression-cxx1y.cpp b/test/SemaCXX/constant-expression-cxx1y.cpp
index dfdf50a..274730d 100644
--- a/test/SemaCXX/constant-expression-cxx1y.cpp
+++ b/test/SemaCXX/constant-expression-cxx1y.cpp
@@ -977,3 +977,8 @@
static_assert(sum(Cs) == 'a' + 'b', ""); // expected-error{{not an integral constant expression}} expected-note{{in call to 'sum(Cs)'}}
constexpr int S = sum(Cs); // expected-error{{must be initialized by a constant expression}} expected-note{{in call}}
}
+
+constexpr void PR28739(int n) { // expected-error {{never produces a constant}}
+ int *p = &n;
+ p += (__int128)(unsigned long)-1; // expected-note {{subexpression}}
+}
