diff options
Diffstat (limited to 'gcc/rtlanal.c')
| -rw-r--r-- | gcc/rtlanal.c | 108 |
1 files changed, 98 insertions, 10 deletions
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c index c992c439bc3..924ef52581c 100644 --- a/gcc/rtlanal.c +++ b/gcc/rtlanal.c @@ -22,6 +22,8 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA #include "config.h" #include "system.h" +#include "coretypes.h" +#include "tm.h" #include "toplev.h" #include "rtl.h" #include "hard-reg-set.h" @@ -153,6 +155,10 @@ 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 +231,10 @@ 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 +279,90 @@ 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. @@ -874,13 +968,10 @@ int reg_set_p (reg, insn) rtx reg, insn; { - rtx body = insn; - /* We can be passed an insn or part of one. If we are passed an insn, check if a side-effect of the insn clobbers REG. */ - if (INSN_P (insn)) - { - if (FIND_REG_INC_NOTE (insn, reg) + if (INSN_P (insn) + && (FIND_REG_INC_NOTE (insn, reg) || (GET_CODE (insn) == CALL_INSN /* We'd like to test call_used_regs here, but rtlanal.c can't reference that variable due to its use in genattrtab. So @@ -891,11 +982,8 @@ reg_set_p (reg, insn) && ((GET_CODE (reg) == REG && REGNO (reg) < FIRST_PSEUDO_REGISTER) || GET_CODE (reg) == MEM - || find_reg_fusage (insn, CLOBBER, reg)))) - return 1; - - body = PATTERN (insn); - } + || find_reg_fusage (insn, CLOBBER, reg))))) + return 1; return set_of (reg, insn) != NULL_RTX; } |