diff options
Diffstat (limited to 'gcc/builtins.c')
| -rw-r--r-- | gcc/builtins.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/gcc/builtins.c b/gcc/builtins.c index 9159a1b..7c833e5 100644 --- a/gcc/builtins.c +++ b/gcc/builtins.c @@ -103,6 +103,7 @@ static rtx expand_builtin_alloca PARAMS ((tree, rtx)); static rtx expand_builtin_ffs PARAMS ((tree, rtx, rtx)); static rtx expand_builtin_frame_address PARAMS ((tree)); static tree stabilize_va_list PARAMS ((tree, int)); +static rtx expand_builtin_expect PARAMS ((tree, rtx)); /* Return the alignment in bits of EXP, a pointer valued expression. But don't return more than MAX_ALIGN no matter what. @@ -2306,6 +2307,48 @@ expand_builtin_ffs (arglist, target, subtarget) abort (); return target; } + +/* Expand a call to __builtin_expect. We return our argument and + emit a NOTE_INSN_EXPECTED_VALUE note. */ + +static rtx +expand_builtin_expect (arglist, target) + tree arglist; + rtx target; +{ + tree exp, c; + rtx note, rtx_c; + + if (arglist == NULL_TREE + || TREE_CHAIN (arglist) == NULL_TREE) + return const0_rtx; + exp = TREE_VALUE (arglist); + c = TREE_VALUE (TREE_CHAIN (arglist)); + + if (TREE_CODE (c) != INTEGER_CST) + { + error ("second arg to `__builtin_expect' must be a constant"); + c = integer_zero_node; + } + + target = expand_expr (exp, target, VOIDmode, EXPAND_NORMAL); + + /* Don't bother with expected value notes for integral constants. */ + if (GET_CODE (target) != CONST_INT) + { + /* We do need to force this into a register so that we can be + moderately sure to be able to correctly interpret the branch + condition later. */ + target = force_reg (GET_MODE (target), target); + + rtx_c = expand_expr (c, NULL_RTX, GET_MODE (target), EXPAND_NORMAL); + + note = emit_note (NULL, NOTE_INSN_EXPECTED_VALUE); + NOTE_EXPECTED_VALUE (note) = gen_rtx_EQ (VOIDmode, target, rtx_c); + } + + return target; +} /* Expand an expression EXP that calls a built-in function, with result going to TARGET if that's convenient @@ -2581,6 +2624,8 @@ expand_builtin (exp, target, subtarget, mode, ignore) return expand_builtin_va_end (arglist); case BUILT_IN_VA_COPY: return expand_builtin_va_copy (arglist); + case BUILT_IN_EXPECT: + return expand_builtin_expect (arglist, target); default: /* just do library call, if unknown builtin */ error ("built-in function `%s' not currently supported", |