diff options
| author | Martin Liska <mliska@suse.cz> | 2020-08-12 09:21:51 +0200 |
|---|---|---|
| committer | Martin Liska <mliska@suse.cz> | 2020-08-12 19:06:24 +0200 |
| commit | d58f078ce2d53e5dab6b3d0d5f960504268e1894 (patch) | |
| tree | 5fc6580370471a4936b7b104d673aa0b8211d47a /gcc/tree-ssa-ccp.c | |
| parent | b418ccb358e428091fb9c6020fd10be5ae40a17a (diff) | |
ipa: fix bit CPP when combined with IPA bit CP
As mentioned in the PR, let's consider the following example:
int
__attribute__((noinline))
foo(int arg)
{
if (arg == 3)
return 1;
if (arg == 4)
return 123;
__builtin_unreachable ();
}
during WPA we find all calls of the function
(yes the call with value 5 is UBSAN):
Node: foo/0:
param [0]: 5 [loc_time: 4, loc_size: 2, prop_time: 0, prop_size: 0]
3 [loc_time: 3, loc_size: 3, prop_time: 0, prop_size: 0]
ctxs: VARIABLE
Bits: value = 0x5, mask = 0x6
in LTRANS we have the following VRP info:
# RANGE [3, 3] NONZERO 3
when we AND masks in get_default_value we end up with 6 & 3 = 2 (0x010).
That means the only second (least significant bit) is unknown and
value (5 = 0x101) & ~mask gives us either 7 (0x111) or 5 (0x101).
That's why if (arg_2(D) == 3) gets optimized to false.
gcc/ChangeLog:
PR ipa/96482
* ipa-cp.c (ipcp_bits_lattice::meet_with_1): Drop value bits
for bits that are unknown.
(ipcp_bits_lattice::set_to_constant): Likewise.
* tree-ssa-ccp.c (get_default_value): Add sanity check that
IPA CP bit info has all bits set to zero in bits that
are unknown.
gcc/testsuite/ChangeLog:
PR ipa/96482
* gcc.dg/ipa/pr96482.c: New test.
Diffstat (limited to 'gcc/tree-ssa-ccp.c')
| -rw-r--r-- | gcc/tree-ssa-ccp.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c index 7e3921869b8..65dffe06530 100644 --- a/gcc/tree-ssa-ccp.c +++ b/gcc/tree-ssa-ccp.c @@ -306,6 +306,9 @@ get_default_value (tree var) { val.lattice_val = CONSTANT; val.value = value; + widest_int ipa_value = wi::to_widest (value); + /* Unknown bits from IPA CP must be equal to zero. */ + gcc_assert (wi::bit_and (ipa_value, mask) == 0); val.mask = mask; if (nonzero_bits != -1) val.mask &= extend_mask (nonzero_bits, |