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[msan] Dynamically grow kNumStackOriginDescrs #92826

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[msan] Dynamically grow kNumStackOriginDescrs #92826

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29 changes: 25 additions & 4 deletions compiler-rt/lib/msan/msan.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -99,10 +99,10 @@ bool msan_init_is_running;
int msan_report_count = 0;

// Array of stack origins.
// FIXME: make it resizable.
static const uptr kNumStackOriginDescrs = 1024 * 1024;
static const char *StackOriginDescr[kNumStackOriginDescrs];
static uptr StackOriginPC[kNumStackOriginDescrs];
// This is resized dynamically by ResizeStackOriginMetadata
static uptr kNumStackOriginDescrs = 0;
static char **StackOriginDescr = nullptr;
static uptr *StackOriginPC = nullptr;
static atomic_uint32_t NumStackOriginDescrs;

void Flags::SetDefaults() {
Expand Down Expand Up @@ -282,7 +282,27 @@ void ScopedThreadLocalStateBackup::Restore() {
void UnpoisonThreadLocalState() {
}

// Grow stack origin metadata structures exponentially if out of space
static void ResizeStackOriginMetadata(u32 id) {
if (id >= kNumStackOriginDescrs) {
if (kNumStackOriginDescrs == 0)
kNumStackOriginDescrs = 1;
else
kNumStackOriginDescrs = kNumStackOriginDescrs * 2;

VReport(2, "Resized stack origin metadata to %lu entries\n",
kNumStackOriginDescrs);
}

StackOriginDescr = (char **)InternalRealloc(
StackOriginDescr, kNumStackOriginDescrs * sizeof(char *));
StackOriginPC = (uptr *)InternalRealloc(StackOriginPC,
kNumStackOriginDescrs * sizeof(uptr));
// No checks needed - InternalRealloc() will die if out of memory
}

const char *GetStackOriginDescr(u32 id, uptr *pc) {
ResizeStackOriginMetadata(id);
CHECK_LT(id, kNumStackOriginDescrs);
if (pc) *pc = StackOriginPC[id];
return StackOriginDescr[id];
Expand Down Expand Up @@ -312,6 +332,7 @@ static inline void SetAllocaOrigin(void *a, uptr size, u32 *id_ptr, char *descr,
u32 id = *id_ptr;
if (id == 0 || id == first_timer) {
u32 idx = atomic_fetch_add(&NumStackOriginDescrs, 1, memory_order_relaxed);
ResizeStackOriginMetadata(idx);
CHECK_LT(idx, kNumStackOriginDescrs);
StackOriginDescr[idx] = descr;
StackOriginPC[idx] = pc;
Expand Down
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