https://github.com/vabridgers updated
https://github.com/llvm/llvm-project/pull/143310
>From edd679e20bb538397236d227e3c228d6b3de44c0 Mon Sep 17 00:00:00 2001
From: Vince Bridgers <vince.a.bridg...@ericsson.com>
Date: Sun, 8 Jun 2025 15:48:04 +0200
Subject: [PATCH] [clang][analyzer] Correct SMT Layer for _BitInt cases
refutations
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Since _BitInt was added later, ASTContext did not comprehend getting
a type by bitwidth that's not a power of 2, and the SMT layer also
did not comprehend this. This led to unexpected crashes using Z3
refutation during randomized testing. The assertion and redacted and
summarized crash stack is shown here.
clang:
../../clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConv.h:103:
static llvm::SMTExprRef clang::ento::SMTConv::fromBinOp(llvm::SMTSolverRef &,
const llvm::SMTExprRef &, const BinaryOperator::Opcode, const
llvm::SMTExprRef &, bool):
Assertion `*Solver->getSort(LHS) == *Solver->getSort(RHS) && "AST's must
have the same sort!"' failed.
...
#9 <address> clang::ento::SMTConv::fromBinOp(std::shared_ptr<llvm::SMTSolver>&,
llvm::SMTExpr const* const&, clang::BinaryOperatorKind, llvm::SMTExpr
const* const&,
bool) SMTConstraintManager.cpp
clang::ASTContext&, llvm::SMTExpr const* const&, clang::QualType,
clang::BinaryOperatorKind, llvm::SMTExpr const* const&, clang::QualType,
clang::QualType*) SMTConstraintManager.cpp
clang::ASTContext&, clang::ento::SymExpr const*, llvm::APSInt const&,
llvm::APSInt const&, bool) SMTConstraintManager.cpp
clang::ento::ExplodedNode const*, clang::ento::PathSensitiveBugReport&)
---
.../Core/PathSensitive/SMTConv.h | 14 +++++++++--
clang/lib/AST/ASTContext.cpp | 11 +++++++--
clang/test/Analysis/bitint-z3.c | 23 +++++++++++++++++++
3 files changed, 44 insertions(+), 4 deletions(-)
create mode 100644 clang/test/Analysis/bitint-z3.c
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConv.h
b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConv.h
index 580b49a38dc72..f2ae6f0e9b48a 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConv.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConv.h
@@ -573,20 +573,30 @@ class SMTConv {
return Ctx.getIntTypeForBitwidth(Int.getBitWidth(), Int.isSigned());
}
+ static inline bool IsPower2(unsigned bits) {
+ return bits > 0 && (bits & (bits - 1)) == 0;
+ }
+
// Get the QualTy for the input APSInt, and fix it if it has a bitwidth of 1.
static inline std::pair<llvm::APSInt, QualType>
fixAPSInt(ASTContext &Ctx, const llvm::APSInt &Int) {
llvm::APSInt NewInt;
+ unsigned APSIntBitwidth = Int.getBitWidth();
+ QualType Ty = getAPSIntType(Ctx, Int);
// FIXME: This should be a cast from a 1-bit integer type to a boolean
type,
// but the former is not available in Clang. Instead, extend the APSInt
// directly.
- if (Int.getBitWidth() == 1 && getAPSIntType(Ctx, Int).isNull()) {
+ if (APSIntBitwidth == 1 && Ty.isNull()) {
NewInt = Int.extend(Ctx.getTypeSize(Ctx.BoolTy));
+ Ty = getAPSIntType(Ctx, NewInt);
+ } else if (!IsPower2(APSIntBitwidth) && !getAPSIntType(Ctx, Int).isNull())
{
+ Ty = getAPSIntType(Ctx, Int);
+ NewInt = Int.extend(Ctx.getTypeSize(Ty));
} else
NewInt = Int;
- return std::make_pair(NewInt, getAPSIntType(Ctx, NewInt));
+ return std::make_pair(NewInt, Ty);
}
// Perform implicit type conversion on binary symbolic expressions.
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index b51f7622288df..e32f0527d24fa 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -13209,9 +13209,16 @@ size_t ASTContext::getSideTableAllocatedMemory() const
{
/// Returns empty type if there is no appropriate target types.
QualType ASTContext::getIntTypeForBitwidth(unsigned DestWidth,
unsigned Signed) const {
- TargetInfo::IntType Ty = getTargetInfo().getIntTypeByWidth(DestWidth,
Signed);
+ // round up to next power of 2 for _BitInt cases
+ unsigned pow2DestWidth = llvm::bit_ceil(DestWidth);
+ // if (pow2DestWidth == 4) pow2DestWidth = 8;
+ if (pow2DestWidth < 8)
+ pow2DestWidth = 8;
+
+ TargetInfo::IntType Ty =
+ getTargetInfo().getIntTypeByWidth(pow2DestWidth, Signed);
CanQualType QualTy = getFromTargetType(Ty);
- if (!QualTy && DestWidth == 128)
+ if (!QualTy && pow2DestWidth == 128)
return Signed ? Int128Ty : UnsignedInt128Ty;
return QualTy;
}
diff --git a/clang/test/Analysis/bitint-z3.c b/clang/test/Analysis/bitint-z3.c
new file mode 100644
index 0000000000000..d50c93acdf117
--- /dev/null
+++ b/clang/test/Analysis/bitint-z3.c
@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=core -w -DNO_CROSSCHECK -verify
%s
+// RUN: %clang_cc1 -analyze -analyzer-checker=core -w -analyzer-config
crosscheck-with-z3=true -verify %s
+// REQUIRES: z3
+
+// The SMTConv layer did not comprehend _BitInt types (because this was an
+// evolved feature) and was crashing due to needed updates in 2 places.
+// Analysis is expected to find these cases using _BitInt without crashing.
+
+_BitInt(35) a;
+int b;
+void c() {
+ int d;
+ if (a)
+ b = d; // expected-warning{{Assigned value is uninitialized
[core.uninitialized.Assign]}}
+}
+
+int *d;
+_BitInt(3) e;
+void f() {
+ int g;
+ d = &g;
+ e ?: 0; // expected-warning{{Address of stack memory associated with local
variable 'g' is still referred to by the global variable 'd' upon returning to
the caller. This will be a dangling reference [core.StackAddressEscape]}}
+}
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