Compute ipa-predicates for conditionals involving __builtin_expect_p std::vector allocator looks as follows:
__attribute__((nodiscard)) struct pair * std::__new_allocator<std::pair<unsigned int, unsigned int> >::allocate (struct __new_allocator * const this, size_type __n, const void * D.27753) { bool _1; long int _2; long int _3; long unsigned int _5; struct pair * _9; <bb 2> [local count: 1073741824]: _1 = __n_7(D) > 1152921504606846975; _2 = (long int) _1; _3 = __builtin_expect (_2, 0); if (_3 != 0) goto <bb 3>; [10.00%] else goto <bb 6>; [90.00%] <bb 3> [local count: 107374184]: if (__n_7(D) > 2305843009213693951) goto <bb 4>; [50.00%] else goto <bb 5>; [50.00%] <bb 4> [local count: 53687092]: std::__throw_bad_array_new_length (); <bb 5> [local count: 53687092]: std::__throw_bad_alloc (); <bb 6> [local count: 966367641]: _5 = __n_7(D) * 8; _9 = operator new (_5); return _9; } So there is check for allocated block size being greater than max_size which is wrapper in __builtin_expect. This makes ipa-fnsummary to give up analyzing predicates and it will miss the fact that the two different calls to __throw will be optimized out if __n is larady smaller than 1152921504606846975 which it is after _M_check_len. This patch extends ipa-fnsummary to understand functions that return their parameter. We still do not get the value range propagated sicne _M_check_len is not inlined early and ipa-prop misses return functions, but we get closer :) Bootstrapped/regtested x86_64-linux, comitted. gcc/ChangeLog: PR tree-optimization/109849 * ipa-fnsummary.cc (decompose_param_expr): Skip functions returning its parameter. (set_cond_stmt_execution_predicate): Return early if predicate was constructed. gcc/testsuite/ChangeLog: PR tree-optimization/109849 * gcc.dg/ipa/pr109849.c: New test. diff --git a/gcc/ipa-fnsummary.cc b/gcc/ipa-fnsummary.cc index 78cbb60d056..a09f6305c63 100644 --- a/gcc/ipa-fnsummary.cc +++ b/gcc/ipa-fnsummary.cc @@ -1516,6 +1516,19 @@ decompose_param_expr (struct ipa_func_body_info *fbi, if (TREE_CODE (expr) != SSA_NAME || SSA_NAME_IS_DEFAULT_DEF (expr)) break; + stmt = SSA_NAME_DEF_STMT (expr); + + if (gcall *call = dyn_cast <gcall *> (stmt)) + { + int flags = gimple_call_return_flags (call); + if (!(flags & ERF_RETURNS_ARG)) + goto fail; + int arg = flags & ERF_RETURN_ARG_MASK; + if (arg >= (int)gimple_call_num_args (call)) + goto fail; + expr = gimple_call_arg (stmt, arg); + continue; + } if (!is_gimple_assign (stmt = SSA_NAME_DEF_STMT (expr))) break; @@ -1664,6 +1677,7 @@ set_cond_stmt_execution_predicate (struct ipa_func_body_info *fbi, } } vec_free (param_ops); + return; } if (TREE_CODE (op) != SSA_NAME) diff --git a/gcc/testsuite/gcc.dg/ipa/pr109849.c b/gcc/testsuite/gcc.dg/ipa/pr109849.c new file mode 100644 index 00000000000..09b62f90d70 --- /dev/null +++ b/gcc/testsuite/gcc.dg/ipa/pr109849.c @@ -0,0 +1,27 @@ +/* { dg-do compile } */ +/* { dg-options "-Os -fdump-ipa-inline-details" } */ +void bad (void); +void +test(int a) +{ + if (__builtin_expect (a>3, 0)) + { + bad (); + bad (); + bad (); + bad (); + bad (); + bad (); + bad (); + bad (); + } +} +void +foo (int a) +{ + if (a>0) + __builtin_unreachable (); + test (a); +} +/* { dg-final { scan-ipa-dump "Inlined 2 calls" "inline" } } */ +/* { dg-final { scan-ipa-dump "Inlining test" "inline" } } */