alloca_vla_interact.cpp
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// RUN: %clangxx_asan -O0 -mllvm -asan-instrument-dynamic-allocas %s -o %t
// RUN: %run %t 2>&1
//
// REQUIRES: stable-runtime
// This testcase checks correct interaction between VLAs and allocas.
#include <assert.h>
#include <stdint.h>
#include <stdlib.h>
#include "sanitizer/asan_interface.h"
// MSVC provides _alloca instead of alloca.
#if defined(_MSC_VER) && !defined(alloca)
# define alloca _alloca
#endif
#if defined(__sun__) && defined(__svr4__)
#include <alloca.h>
#endif
#define RZ 32
__attribute__((noinline)) void foo(int len) {
char *top, *bot;
// This alloca call should live until the end of foo.
char *alloca1 = (char *)alloca(len);
assert(!(reinterpret_cast<uintptr_t>(alloca1) & 31L));
// This should be first poisoned address after loop.
top = alloca1 - RZ;
for (int i = 0; i < 32; ++i) {
// Check that previous alloca was unpoisoned at the end of iteration.
if (i) assert(!__asan_region_is_poisoned(bot, 96));
// VLA is unpoisoned at the end of iteration.
volatile char array[i];
assert(!(reinterpret_cast<uintptr_t>(array) & 31L));
// Alloca is unpoisoned at the end of iteration,
// because dominated by VLA.
bot = (char *)alloca(i) - RZ;
}
// Check that all allocas from loop were unpoisoned correctly.
void *q = __asan_region_is_poisoned(bot, (char *)top - (char *)bot + 1);
assert(q == top);
}
int main(int argc, char **argv) {
foo(32);
return 0;
}