https://github.com/osamakader updated https://github.com/llvm/llvm-project/pull/160015
>From 0e22b9d11a26fcab71c1be25908722b8e126ed6b Mon Sep 17 00:00:00 2001 From: Osama Abdelkader <[email protected]> Date: Mon, 22 Sep 2025 00:59:48 +0300 Subject: [PATCH] [clang][bytecode] Fix unknown size arrays crash in clang bytecode This fixes issue #153948 where clang crashes with assertion failure 'Array of unknown size' when evaluating strlen() on external const char[] declarations. The issue was in evaluateStrlen() which called getNumElems() on unknown size arrays, leading to an assertion in Descriptor::getSize(). Fix: Add check for isDummy() || isUnknownSizeArray() before calling getNumElems() to gracefully handle unknown size arrays by returning false (indicating strlen cannot be evaluated at compile time). Tested with the reproducer from the GitHub issue and added test case. Signed-off-by: Osama Abdelkader <[email protected]> --- clang/lib/AST/ByteCode/Context.cpp | 3 +++ .../test/AST/ByteCode/strlen-unknown-size-array.cpp | 13 +++++++++++++ 2 files changed, 16 insertions(+) create mode 100644 clang/test/AST/ByteCode/strlen-unknown-size-array.cpp diff --git a/clang/lib/AST/ByteCode/Context.cpp b/clang/lib/AST/ByteCode/Context.cpp index cfda6e8ded760..8860bcc54a9c1 100644 --- a/clang/lib/AST/ByteCode/Context.cpp +++ b/clang/lib/AST/ByteCode/Context.cpp @@ -245,6 +245,9 @@ bool Context::evaluateStrlen(State &Parent, const Expr *E, uint64_t &Result) { if (!FieldDesc->isPrimitiveArray()) return false; + if (Ptr.isDummy() || Ptr.isUnknownSizeArray()) + return false; + unsigned N = Ptr.getNumElems(); if (Ptr.elemSize() == 1) { Result = strnlen(reinterpret_cast<const char *>(Ptr.getRawAddress()), N); diff --git a/clang/test/AST/ByteCode/strlen-unknown-size-array.cpp b/clang/test/AST/ByteCode/strlen-unknown-size-array.cpp new file mode 100644 index 0000000000000..ddc857009f57d --- /dev/null +++ b/clang/test/AST/ByteCode/strlen-unknown-size-array.cpp @@ -0,0 +1,13 @@ +// RUN: %clang_cc1 -std=c++20 -fexperimental-new-constant-interpreter %s -verify +// RUN: %clang_cc1 -std=c++20 %s -verify=ref + +// expected-no-diagnostics +// ref-no-diagnostics + +/// Test that __builtin_strlen() on external/unknown declarations doesn't crash the bytecode interpreter. +extern const char s[]; +void foo(char *x) +{ + unsigned long len = __builtin_strlen(s); + __builtin_strcpy(x, s); +} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
