erichkeane created this revision.
erichkeane added reviewers: eli.friedman, rjmccall.
As requested here:https://bugs.llvm.org/show_bug.cgi?id=37633
permit the __builtin_*_overflow builtins in constexpr functions.
Repository:
rC Clang
https://reviews.llvm.org/D48040
Files:
lib/AST/ExprConstant.cpp
lib/Sema/SemaChecking.cpp
test/SemaCXX/builtins-overflow.cpp
Index: lib/AST/ExprConstant.cpp
===================================================================
--- lib/AST/ExprConstant.cpp
+++ lib/AST/ExprConstant.cpp
@@ -8155,6 +8155,121 @@
case Builtin::BIomp_is_initial_device:
// We can decide statically which value the runtime would return if called.
return Success(Info.getLangOpts().OpenMPIsDevice ? 0 : 1, E);
+ case Builtin::BI__builtin_add_overflow:
+ case Builtin::BI__builtin_sub_overflow:
+ case Builtin::BI__builtin_mul_overflow:
+ case Builtin::BI__builtin_sadd_overflow:
+ case Builtin::BI__builtin_uadd_overflow:
+ case Builtin::BI__builtin_uaddl_overflow:
+ case Builtin::BI__builtin_uaddll_overflow:
+ case Builtin::BI__builtin_usub_overflow:
+ case Builtin::BI__builtin_usubl_overflow:
+ case Builtin::BI__builtin_usubll_overflow:
+ case Builtin::BI__builtin_umul_overflow:
+ case Builtin::BI__builtin_umull_overflow:
+ case Builtin::BI__builtin_umulll_overflow:
+ case Builtin::BI__builtin_saddl_overflow:
+ case Builtin::BI__builtin_saddll_overflow:
+ case Builtin::BI__builtin_ssub_overflow:
+ case Builtin::BI__builtin_ssubl_overflow:
+ case Builtin::BI__builtin_ssubll_overflow:
+ case Builtin::BI__builtin_smul_overflow:
+ case Builtin::BI__builtin_smull_overflow:
+ case Builtin::BI__builtin_smulll_overflow: {
+ LValue ResultLValue;
+ APSInt LHS, RHS;
+
+ QualType ResultType = E->getArg(2)->getType()->getPointeeType();
+ if (!EvaluateInteger(E->getArg(0), LHS, Info) ||
+ !EvaluateInteger(E->getArg(1), RHS, Info) ||
+ !EvaluatePointer(E->getArg(2), ResultLValue, Info))
+ return false;
+
+ APSInt Result;
+ bool DidOverflow = false;
+
+ // If the types don't have to match, enlarge all 3 to the largest of them.
+ if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
+ BuiltinOp == Builtin::BI__builtin_sub_overflow ||
+ BuiltinOp == Builtin::BI__builtin_mul_overflow) {
+ bool IsSigned = LHS.isSigned() || RHS.isSigned() ||
+ ResultType->isSignedIntegerOrEnumerationType();
+ bool AllSigned = LHS.isSigned() && RHS.isSigned() &&
+ ResultType->isSignedIntegerOrEnumerationType();
+ uint64_t LHSSize = LHS.getBitWidth();
+ uint64_t RHSSize = RHS.getBitWidth();
+ uint64_t ResultSize = Info.Ctx.getTypeSize(ResultType);
+ uint64_t MaxBits = std::max(std::max(LHSSize, RHSSize), ResultSize);
+
+ // Add an additional bit if the signedness isn't uniformly agreed to. We
+ // could do this ONLY if there is a signed and an unsigned that both have
+ // MaxBits, but the code to check that is pretty nasty. The issue will be
+ // caught in the shrink-to-result later anyway.
+ if (IsSigned && !AllSigned)
+ ++MaxBits;
+
+ LHS = APSInt(IsSigned ? LHS.sextOrSelf(MaxBits) : LHS.zextOrSelf(MaxBits),
+ !IsSigned);
+ RHS = APSInt(IsSigned ? RHS.sextOrSelf(MaxBits) : RHS.zextOrSelf(MaxBits),
+ !IsSigned);
+ Result = APSInt(MaxBits, !IsSigned);
+ }
+
+ // Find largest int.
+ switch (BuiltinOp) {
+ default:
+ llvm_unreachable("Invalid value for BuiltinOp");
+ case Builtin::BI__builtin_add_overflow:
+ case Builtin::BI__builtin_sadd_overflow:
+ case Builtin::BI__builtin_saddl_overflow:
+ case Builtin::BI__builtin_saddll_overflow:
+ case Builtin::BI__builtin_uadd_overflow:
+ case Builtin::BI__builtin_uaddl_overflow:
+ case Builtin::BI__builtin_uaddll_overflow:
+ Result = LHS.isSigned() ? LHS.sadd_ov(RHS, DidOverflow)
+ : LHS.uadd_ov(RHS, DidOverflow);
+ break;
+ case Builtin::BI__builtin_sub_overflow:
+ case Builtin::BI__builtin_ssub_overflow:
+ case Builtin::BI__builtin_ssubl_overflow:
+ case Builtin::BI__builtin_ssubll_overflow:
+ case Builtin::BI__builtin_usub_overflow:
+ case Builtin::BI__builtin_usubl_overflow:
+ case Builtin::BI__builtin_usubll_overflow:
+ Result = LHS.isSigned() ? LHS.ssub_ov(RHS, DidOverflow)
+ : LHS.usub_ov(RHS, DidOverflow);
+ break;
+ case Builtin::BI__builtin_mul_overflow:
+ case Builtin::BI__builtin_smul_overflow:
+ case Builtin::BI__builtin_smull_overflow:
+ case Builtin::BI__builtin_smulll_overflow:
+ case Builtin::BI__builtin_umul_overflow:
+ case Builtin::BI__builtin_umull_overflow:
+ case Builtin::BI__builtin_umulll_overflow:
+ Result = LHS.isSigned() ? LHS.smul_ov(RHS, DidOverflow)
+ : LHS.umul_ov(RHS, DidOverflow);
+ break;
+ }
+
+ // In the case where multiple sizes are allowed, truncate and see if
+ // the values are the same.
+ if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
+ BuiltinOp == Builtin::BI__builtin_sub_overflow ||
+ BuiltinOp == Builtin::BI__builtin_mul_overflow) {
+ // It won't GROW, since that isn't possible, so use this to allow
+ // TruncOrSelf.
+ APSInt Temp = Result.extOrTrunc(Info.Ctx.getTypeSize(ResultType));
+ Temp.setIsSigned(ResultType->isSignedIntegerOrEnumerationType());
+
+ if (!APSInt::isSameValue(Temp, Result))
+ DidOverflow = true;
+ Result = Temp;
+ }
+
+ APValue APV{Result};
+ handleAssignment(Info, E, ResultLValue, ResultType, APV);
+ return Success(DidOverflow, E);
+ }
}
}
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -197,13 +197,17 @@
// First two arguments should be integers.
for (unsigned I = 0; I < 2; ++I) {
- Expr *Arg = TheCall->getArg(I);
- QualType Ty = Arg->getType();
+ ExprResult Arg = TheCall->getArg(I);
+ QualType Ty = Arg.get()->getType();
if (!Ty->isIntegerType()) {
- S.Diag(Arg->getLocStart(), diag::err_overflow_builtin_must_be_int)
- << Ty << Arg->getSourceRange();
+ S.Diag(Arg.get()->getLocStart(), diag::err_overflow_builtin_must_be_int)
+ << Ty << Arg.get()->getSourceRange();
return true;
}
+ InitializedEntity Entity = InitializedEntity::InitializeParameter(
+ S.getASTContext(), Ty, /*consume*/ false);
+ Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
+ TheCall->setArg(I, Arg.get());
}
// Third argument should be a pointer to a non-const integer.
Index: test/SemaCXX/builtins-overflow.cpp
===================================================================
--- test/SemaCXX/builtins-overflow.cpp
+++ test/SemaCXX/builtins-overflow.cpp
@@ -0,0 +1,74 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c++17 -verify %s
+// expected-no-diagnostics
+
+#include <limits.h>
+#define OVERFLOWS 103
+
+
+template <typename RET, typename LHS, typename RHS>
+constexpr RET add(LHS &&lhs, RHS &&rhs) {
+ RET sum{};
+ return __builtin_add_overflow(lhs, rhs, &sum) ? OVERFLOWS : sum;
+}
+
+static_assert(add<short>(static_cast<char>(120), static_cast<char>(10)) == 130);
+static_assert(add<short>(static_cast<char>(120), static_cast<short>(10)) == 130);
+static_assert(add<char>(static_cast<short>(120), static_cast<short>(10)) == OVERFLOWS);
+static_assert(add<unsigned int>(INT_MAX, INT_MAX) == static_cast<unsigned int>(INT_MAX) * 2u);
+static_assert(add<int>(static_cast<unsigned int>(INT_MAX), 1u) == OVERFLOWS);
+
+static_assert(add<int>(17, 22) == 39);
+static_assert(add<int>(INT_MAX - 22, 23) == OVERFLOWS);
+static_assert(add<int>(INT_MIN + 22, -23) == OVERFLOWS);
+
+template <typename RET, typename LHS, typename RHS>
+constexpr RET sub(LHS &&lhs, RHS &&rhs) {
+ RET sum{};
+ return __builtin_sub_overflow(lhs, rhs, &sum) ? OVERFLOWS : sum;
+}
+
+static_assert(sub<unsigned char>(static_cast<char>(0),static_cast<char>(1)) == OVERFLOWS);
+static_assert(sub<char>(static_cast<unsigned char>(0),static_cast<unsigned char>(1)) == -1);
+static_assert(sub<unsigned short>(static_cast<short>(0),static_cast<short>(1)) == OVERFLOWS);
+
+static_assert(sub<int>(17,22) == -5);
+static_assert(sub<int>(INT_MAX - 22, -23) == OVERFLOWS);
+static_assert(sub<int>(INT_MIN + 22, 23) == OVERFLOWS);
+
+template <typename RET, typename LHS, typename RHS>
+constexpr RET mul(LHS &&lhs, RHS &&rhs) {
+ RET sum{};
+ return __builtin_mul_overflow(lhs, rhs, &sum) ? OVERFLOWS : sum;
+}
+
+static_assert(mul<int>(17,22) == 374);
+static_assert(mul<int>(INT_MAX / 22, 23) == OVERFLOWS);
+static_assert(mul<int>(INT_MIN / 22, -23) == OVERFLOWS);
+
+constexpr auto sadd(int lhs, int rhs) {
+ int sum{};
+ return __builtin_sadd_overflow(lhs, rhs, &sum) ? OVERFLOWS : sum;
+}
+
+static_assert(sadd(17,22) == 39);
+static_assert(sadd(INT_MAX - 22, 23) == OVERFLOWS);
+static_assert(sadd(INT_MIN + 22, -23) == OVERFLOWS);
+
+constexpr auto ssub(int lhs, int rhs) {
+ int sum{};
+ return __builtin_ssub_overflow(lhs, rhs, &sum) ? OVERFLOWS : sum;
+}
+
+static_assert(ssub(17,22) == -5);
+static_assert(ssub(INT_MAX - 22, -23) == OVERFLOWS);
+static_assert(ssub(INT_MIN + 22, 23) == OVERFLOWS);
+
+constexpr auto smul(int lhs, int rhs) {
+ int sum{};
+ return __builtin_smul_overflow(lhs, rhs, &sum) ? OVERFLOWS : sum;
+}
+
+static_assert(smul(17,22) == 374);
+static_assert(smul(INT_MAX / 22, 23) == OVERFLOWS);
+static_assert(smul(INT_MIN / 22, -23) == OVERFLOWS);
+
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