diff options
Diffstat (limited to 'ipa-fix-bit-CPP-when-combined-with-IPA-bit-CP.patch')
| -rw-r--r-- | ipa-fix-bit-CPP-when-combined-with-IPA-bit-CP.patch | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/ipa-fix-bit-CPP-when-combined-with-IPA-bit-CP.patch b/ipa-fix-bit-CPP-when-combined-with-IPA-bit-CP.patch new file mode 100644 index 000000000000..cd812623cec3 --- /dev/null +++ b/ipa-fix-bit-CPP-when-combined-with-IPA-bit-CP.patch @@ -0,0 +1,147 @@ +From d58f078ce2d53e5dab6b3d0d5f960504268e1894 Mon Sep 17 00:00:00 2001 +From: Martin Liska <mliska@suse.cz> +Date: Wed, 12 Aug 2020 09:21:51 +0200 +Subject: [PATCH] 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. +--- + gcc/ipa-cp.c | 3 +- + gcc/testsuite/gcc.dg/ipa/pr96482.c | 44 ++++++++++++++++++++++++++++++ + gcc/tree-ssa-ccp.c | 3 ++ + 3 files changed, 49 insertions(+), 1 deletion(-) + create mode 100644 gcc/testsuite/gcc.dg/ipa/pr96482.c + +diff --git a/gcc/ipa-cp.c b/gcc/ipa-cp.c +index 945a69977f3..2b21280d919 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 00000000000..68ead798d28 +--- /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 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, +-- +2.28.0 + |