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author | Martin Liska <mliska@suse.cz> | 2020-08-12 09:21:51 +0200 |
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committer | Martin Liska <mliska@suse.cz> | 2020-08-12 19:06:24 +0200 |
commit | d58f078ce2d53e5dab6b3d0d5f960504268e1894 (patch) | |
tree | 5fc6580370471a4936b7b104d673aa0b8211d47a | |
parent | b418ccb358e428091fb9c6020fd10be5ae40a17a (diff) | |
download | gcc-d58f078ce2d53e5dab6b3d0d5f960504268e1894.zip gcc-d58f078ce2d53e5dab6b3d0d5f960504268e1894.tar.gz gcc-d58f078ce2d53e5dab6b3d0d5f960504268e1894.tar.bz2 |
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.
-rw-r--r-- | gcc/ipa-cp.c | 3 | ||||
-rw-r--r-- | gcc/testsuite/gcc.dg/ipa/pr96482.c | 44 | ||||
-rw-r--r-- | gcc/tree-ssa-ccp.c | 3 |
3 files changed, 49 insertions, 1 deletions
diff --git a/gcc/ipa-cp.c b/gcc/ipa-cp.c index 945a699..2b21280 100644 --- a/gcc/ipa-cp.c +++ b/gcc/ipa-cp.c @@ -1011,7 +1011,7 @@ ipcp_bits_lattice::set_to_constant (widest_int value, widest_int mask) { gcc_assert (top_p ()); m_lattice_val = IPA_BITS_CONSTANT; - m_value = value; + m_value = wi::bit_and (wi::bit_not (mask), value); m_mask = mask; return true; } @@ -1048,6 +1048,7 @@ ipcp_bits_lattice::meet_with_1 (widest_int value, widest_int mask, widest_int old_mask = m_mask; m_mask = (m_mask | mask) | (m_value ^ value); + m_value &= value; if (wi::sext (m_mask, precision) == -1) return set_to_bottom (); diff --git a/gcc/testsuite/gcc.dg/ipa/pr96482.c b/gcc/testsuite/gcc.dg/ipa/pr96482.c new file mode 100644 index 0000000..68ead79 --- /dev/null +++ b/gcc/testsuite/gcc.dg/ipa/pr96482.c @@ -0,0 +1,44 @@ +/* PR ipa/96482 */ +/* { dg-do run } */ +/* { dg-options "-O2 -flto" } */ +/* { dg-require-effective-target lto } */ + +int +__attribute__((noinline)) +foo(int arg) +{ + if (arg == 3) + return 1; + if (arg == 4) + return 123; + + __builtin_unreachable (); +} + +int +__attribute__((noinline)) +baz(int x) +{ + if (x != 0) + return foo(3); /* called */ + + return 1; +} + +int +__attribute__((noinline)) +bar(int x) +{ + if (x == 0) + return foo(5); /* not executed */ + + return 1; +} + +int main(int argc, char **argv) +{ + if (bar(argc) != baz(argc)) + __builtin_abort (); + + return 0; +} diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c index 7e39218..65dffe0 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, |