On Sat, Feb 1, 2020 at 1:04 AM Uecker, Martin <martin.uec...@med.uni-goettingen.de> wrote: > > > > Hi Richard and Joseph, > > for discussion: here is my simple patch > for __builtin_escape/__builtin_bless. > > Maybe it does something stupid.
I'd use an internal function once the frontend inserts the calls, we shouldn't expose those to the user. I expect the builtins to show as quite invasive with their data dependence blocking many optimizations. Any reason that __builtin_escape is not marked as const? Do you try to prevent code motion of it so flow-sensitive "escape" analysis can be used? But nothing prevents hoisting of the bless call across the escape one. Richard. > > Best, > Martin > > > diff --git a/gcc/builtins.c b/gcc/builtins.c > index e4a8694054e..d0046135213 100644 > --- a/gcc/builtins.c > +++ b/gcc/builtins.c > @@ -6014,6 +6014,31 @@ expand_builtin_unreachable (void) > emit_barrier (); > } > > + > +static rtx > +expand_builtin_escape (tree exp, rtx target) > +{ > + if (call_expr_nargs (exp) < 1) > + return const0_rtx; > + > + target = expand_expr (CALL_EXPR_ARG (exp, 0), target, Pmode, > + EXPAND_NORMAL); > + > + return target; > +} > + > +static rtx > +expand_builtin_bless (tree exp, rtx target) > +{ > + if (call_expr_nargs (exp) < 1) > + return const0_rtx; > + > + target = expand_expr (CALL_EXPR_ARG (exp, 0), target, Pmode, > + EXPAND_NORMAL); > + > + return target; > +} > + > /* Expand EXP, a call to fabs, fabsf or fabsl. > Return NULL_RTX if a normal call should be emitted rather than expanding > the function inline. If convenient, the result should be placed > @@ -8304,6 +8329,12 @@ expand_builtin (tree exp, rtx target, rtx subtarget, > machine_mode mode, > expand_builtin_unreachable (); > return const0_rtx; > > + case BUILT_IN_ESCAPE: > + return expand_builtin_escape (exp, target); > + > + case BUILT_IN_BLESS: > + return expand_builtin_bless (exp, target); > + > CASE_FLT_FN (BUILT_IN_SIGNBIT): > case BUILT_IN_SIGNBITD32: > case BUILT_IN_SIGNBITD64: > diff --git a/gcc/builtins.def b/gcc/builtins.def > index fa8b0641ab1..9264a0fdaab 100644 > --- a/gcc/builtins.def > +++ b/gcc/builtins.def > @@ -865,6 +865,8 @@ DEF_EXT_LIB_BUILTIN (BUILT_IN_EXECVP, "execvp", > BT_FN_INT_CONST_STRING_PT > DEF_EXT_LIB_BUILTIN (BUILT_IN_EXECVE, "execve", > BT_FN_INT_CONST_STRING_PTR_CONST_STRING_PTR_CONST_STRING, ATTR_NOTHROW_LIST) > DEF_LIB_BUILTIN (BUILT_IN_EXIT, "exit", BT_FN_VOID_INT, > ATTR_NORETURN_NOTHROW_LIST) > DEF_GCC_BUILTIN (BUILT_IN_EXPECT, "expect", BT_FN_LONG_LONG_LONG, > ATTR_CONST_NOTHROW_LEAF_LIST) > +DEF_GCC_BUILTIN (BUILT_IN_ESCAPE, "escape", BT_FN_PTR_PTR, > ATTR_NOTHROW_LEAF_LIST) > +DEF_GCC_BUILTIN (BUILT_IN_BLESS, "bless", BT_FN_PTR_PTR, > ATTR_CONST_NOTHROW_LEAF_LIST) > DEF_GCC_BUILTIN (BUILT_IN_EXPECT_WITH_PROBABILITY, > "expect_with_probability", BT_FN_LONG_LONG_LONG_DOUBLE, > ATTR_CONST_NOTHROW_LEAF_LIST) > DEF_GCC_BUILTIN (BUILT_IN_ASSUME_ALIGNED, "assume_aligned", > BT_FN_PTR_CONST_PTR_SIZE_VAR, ATTR_CONST_NOTHROW_LEAF_LIST) > DEF_GCC_BUILTIN (BUILT_IN_EXTEND_POINTER, "extend_pointer", > BT_FN_UNWINDWORD_PTR, ATTR_CONST_NOTHROW_LEAF_LIST) > diff --git a/gcc/testsuite/gcc.dg/alias-17.c b/gcc/testsuite/gcc.dg/alias-17.c > new file mode 100644 > index 00000000000..c375e4027ca > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/alias-17.c > @@ -0,0 +1,29 @@ > +/* { dg-do run } */ > +/* { dg-options "-O1" } */ > + > + > +static > +int test(int a, int b, int c) > +{ > + int x, y; > + int d = (&x < &y) ? 1 : -1; > + if (a) __builtin_escape(&y); > + y = 0; //! > + int *q = &x; > + q += d; > + int *r = q; > + if (b) r = __builtin_bless(q); > + *(c ? r : q) = 1; > + return y; > +} > + > +int main() > +{ > + if (0 != test(0, 0, 1)) __builtin_abort(); > + if (0 != test(0, 1, 0)) __builtin_abort(); > + if (0 != test(0, 1, 1)) __builtin_abort(); > + if (0 != test(1, 0, 1)) __builtin_abort(); > +// if (0 != test(1, 1, 0)) __builtin_abort(); > + if (0 == test(1, 1, 1)) __builtin_abort(); > + return 0; > +} > diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c > index 670676f20c3..d5befff71a6 100644 > --- a/gcc/tree-ssa-alias.c > +++ b/gcc/tree-ssa-alias.c > @@ -2462,6 +2462,8 @@ ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *ref, > bool tbaa_p) > } > > /* The following builtins do not read from memory. */ > + case BUILT_IN_ESCAPE: > + case BUILT_IN_BLESS: > case BUILT_IN_FREE: > case BUILT_IN_MALLOC: > case BUILT_IN_POSIX_MEMALIGN: > diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c > index be6647db894..53a38a04ebb 100644 > --- a/gcc/tree-ssa-ccp.c > +++ b/gcc/tree-ssa-ccp.c > @@ -1963,6 +1963,8 @@ evaluate_stmt (gimple *stmt) > break; > > /* These builtins return their first argument, unmodified. */ > + case BUILT_IN_ESCAPE: > + case BUILT_IN_BLESS: > case BUILT_IN_MEMCPY: > case BUILT_IN_MEMMOVE: > case BUILT_IN_MEMSET: > diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c > index 416a26c996c..003349c7278 100644 > --- a/gcc/tree-ssa-structalias.c > +++ b/gcc/tree-ssa-structalias.c > @@ -4381,6 +4381,24 @@ find_func_aliases_for_builtin_call (struct function > *fn, gcall *t) > in the alias-oracle query functions explicitly! */ > switch (DECL_FUNCTION_CODE (fndecl)) > { > + case BUILT_IN_ESCAPE: > + { > + make_escape_constraint (gimple_call_arg (t, 0)); > + return true; > + } > + case BUILT_IN_BLESS: > + { > + tree lhs = gimple_call_lhs (t); > + struct constraint_expr rhsc, *lhsp; > + unsigned j; > + get_constraint_for (lhs, &lhsc); > + rhsc.var = nonlocal_id; > + rhsc.offset = 0; > + rhsc.type = SCALAR; > + FOR_EACH_VEC_ELT (lhsc, j, lhsp) > + process_constraint (new_constraint (*lhsp, rhsc)); > + return true; > + } > /* All the following functions return a pointer to the same object > as their first argument points to. The functions do not add > to the ESCAPED solution. The functions make the first argument > @@ -5257,6 +5275,7 @@ find_func_clobbers (struct function *fn, gimple *origt) > if (gimple_call_builtin_p (t, BUILT_IN_NORMAL)) > switch (DECL_FUNCTION_CODE (decl)) > { > + > /* The following functions use and clobber memory pointed to > by their arguments. */ > case BUILT_IN_STRCPY: > @@ -5349,6 +5368,9 @@ find_func_clobbers (struct function *fn, gimple *origt) > case BUILT_IN_ASSUME_ALIGNED: > case BUILT_IN_FREE: > return; > + case BUILT_IN_ESCAPE: > + case BUILT_IN_BLESS: > + return; > /* Trampolines are of no interest to us. */ > case BUILT_IN_INIT_TRAMPOLINE: > case BUILT_IN_ADJUST_TRAMPOLINE: