(combine_instructions): In initial scan of insns, handle a REG_INC note's affect...

(combine_instructions): In initial scan of insns, handle a REG_INC
note's affect on sign bit copies and nonzero bits.
(set_nonzero_bits_and_sign_copies): Treat a zero SET arg as a CLOBBER.

From-SVN: r11762

diff --git a/gcc/combine.c b/gcc/combine.c
index fdc0060..9efa2ab 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -536,6 +536,12 @@ combine_instructions (f, nregs)
        {
          note_stores (PATTERN (insn), set_nonzero_bits_and_sign_copies);
          record_dead_and_set_regs (insn);
+
+#ifdef AUTO_INC_DEC
+         for (links = REG_NOTES (insn); links; links = XEXP (links, 1))
+           if (REG_NOTE_KIND (links) == REG_INC)
+             set_nonzero_bits_and_sign_copies (XEXP (links, 0), NULL_RTX);
+#endif
        }
 
       if (GET_CODE (insn) == CODE_LABEL)
@@ -728,7 +734,7 @@ set_nonzero_bits_and_sign_copies (x, set)
            & ((REGSET_ELT_TYPE) 1 << (REGNO (x) % REGSET_ELT_BITS)))
       && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT)
     {
-      if (GET_CODE (set) == CLOBBER)
+      if (set == 0 || GET_CODE (set) == CLOBBER)
        {
          reg_nonzero_bits[REGNO (x)] = GET_MODE_MASK (GET_MODE (x));
          reg_sign_bit_copies[REGNO (x)] = 0;