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/* { dg-do compile { target x86_64-*-* } } */
/* { dg-require-effective-target lp64 } */
/* Reproducer for false positive from -Wanalyzer-null-dereference seen
in Linux kernel (drivers/staging/wfx/sta.c; GPL-2.0) due to
the analyzer not grokking that array_index_mask_nospec is
effectively pure, and thus not realizing that array_index_no_spec
is also pure, leading to wdev_to_wvif not being treated as pure,
and thus able to return non-NULL and then NULL. */
typedef unsigned char u8;
#define NULL ((void *)0)
/* Types. */
struct ieee80211_vif {
int placeholder;
/* snip */
u8 drv_priv[];
};
struct wfx_dev {
/* snip */
struct ieee80211_vif *vif[2];
/* snip */
};
struct wfx_vif {
struct wfx_dev *wdev;
struct ieee80211_vif *vif;
/* snip */
};
/* Copied from arch/x86/include/asm/barrier.h */
static inline unsigned long array_index_mask_nospec(unsigned long index,
unsigned long size)
{
unsigned long mask;
asm volatile ("cmp %1,%2; sbb %0,%0;"
:"=r" (mask)
:"g"(size),"r" (index)
:"cc");
return mask;
}
/* Simplified from include/linux/kernel.h */
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
/* Simplified from include/linux/nospec.h */
#define array_index_nospec(index, size) \
({ \
typeof(index) _i = (index); \
typeof(size) _s = (size); \
unsigned long _mask = array_index_mask_nospec(_i, _s); \
/* snip */ \
(typeof(_i)) (_i & _mask); \
})
/* Simplified from drivers/staging/wfx/wfx.h */
static inline struct wfx_vif *wdev_to_wvif(struct wfx_dev *wdev, int vif_id) {
vif_id = array_index_nospec(vif_id, ARRAY_SIZE(wdev->vif));
if (!wdev->vif[vif_id]) {
return NULL;
}
return (struct wfx_vif *)wdev->vif[vif_id]->drv_priv;
}
struct ieee80211_vif *test (struct wfx_vif *wvif) {
if (wdev_to_wvif(wvif->wdev, 1))
return wdev_to_wvif(wvif->wdev, 1)->vif; /* { dg-bogus "dereference of NULL" } */
else
return NULL;
}
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