diff options
Diffstat (limited to 'gcc/rtlanal.c')
| -rw-r--r-- | gcc/rtlanal.c | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c index f5e104fbdb9..f45f888517c 100644 --- a/gcc/rtlanal.c +++ b/gcc/rtlanal.c @@ -153,6 +153,10 @@ rtx_varies_p (x, for_alias) case LABEL_REF: return 0; + case ADDRESSOF: + /* This will resolve to some offset from the frame pointer. */ + return 0; + case REG: /* Note that we have to test for the actual rtx used for the frame and arg pointers and not just the register number in case we have @@ -225,6 +229,10 @@ rtx_addr_can_trap_p (x) case LABEL_REF: return 0; + case ADDRESSOF: + /* This will resolve to some offset from the frame pointer. */ + return 0; + case REG: /* As in rtx_varies_p, we have to use the actual rtx, not reg number. */ if (x == frame_pointer_rtx || x == hard_frame_pointer_rtx @@ -269,6 +277,90 @@ rtx_addr_can_trap_p (x) return 1; } +/* Return true if X is an address that is known to not be zero. */ + +bool +nonzero_address_p (x) + rtx x; +{ + enum rtx_code code = GET_CODE (x); + + switch (code) + { + case SYMBOL_REF: + return !SYMBOL_REF_WEAK (x); + + case LABEL_REF: + return true; + + case ADDRESSOF: + /* This will resolve to some offset from the frame pointer. */ + return true; + + case REG: + /* As in rtx_varies_p, we have to use the actual rtx, not reg number. */ + if (x == frame_pointer_rtx || x == hard_frame_pointer_rtx + || x == stack_pointer_rtx + || (x == arg_pointer_rtx && fixed_regs[ARG_POINTER_REGNUM])) + return true; + /* All of the virtual frame registers are stack references. */ + if (REGNO (x) >= FIRST_VIRTUAL_REGISTER + && REGNO (x) <= LAST_VIRTUAL_REGISTER) + return true; + return false; + + case CONST: + return nonzero_address_p (XEXP (x, 0)); + + case PLUS: + if (GET_CODE (XEXP (x, 1)) == CONST_INT) + { + /* Pointers aren't allowed to wrap. If we've got a register + that is known to be a pointer, and a positive offset, then + the composite can't be zero. */ + if (INTVAL (XEXP (x, 1)) > 0 + && REG_P (XEXP (x, 0)) + && REG_POINTER (XEXP (x, 0))) + return true; + + return nonzero_address_p (XEXP (x, 0)); + } + /* Handle PIC references. */ + else if (XEXP (x, 0) == pic_offset_table_rtx + && CONSTANT_P (XEXP (x, 1))) + return true; + return false; + + case PRE_MODIFY: + /* Similar to the above; allow positive offsets. Further, since + auto-inc is only allowed in memories, the register must be a + pointer. */ + if (GET_CODE (XEXP (x, 1)) == CONST_INT + && INTVAL (XEXP (x, 1)) > 0) + return true; + return nonzero_address_p (XEXP (x, 0)); + + case PRE_INC: + /* Similarly. Further, the offset is always positive. */ + return true; + + case PRE_DEC: + case POST_DEC: + case POST_INC: + case POST_MODIFY: + return nonzero_address_p (XEXP (x, 0)); + + case LO_SUM: + return nonzero_address_p (XEXP (x, 1)); + + default: + break; + } + + /* If it isn't one of the case above, might be zero. */ + return false; +} + /* Return 1 if X refers to a memory location whose address cannot be compared reliably with constant addresses, or if X refers to a BLKmode memory object. |