+2004-02-11 Richard Henderson <rth@redhat.com>
+
+ * flow.c (insn_dead_p): A clobber of a dead hard register is a
+ dead insn after reload.
+
2004-02-11 Ulrich Weigand <uweigand@de.ibm.com>
* tree.h (frame_base_decl): Add GTY marker.
}
/* A CLOBBER of a pseudo-register that is dead serves no purpose. That
- is not necessarily true for hard registers. */
- else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
- && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
- && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
- return 1;
-
- /* We do not check other CLOBBER or USE here. An insn consisting of just
- a CLOBBER or just a USE should not be deleted. */
+ is not necessarily true for hard registers until after reload. */
+ else if (code == CLOBBER)
+ {
+ if (GET_CODE (XEXP (x, 0)) == REG
+ && (REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
+ || reload_completed)
+ && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
+ return 1;
+ }
+
+ /* ??? A base USE is a historical relic. It ought not be needed anymore.
+ Instances where it is still used are either (1) temporary and the USE
+ escaped the pass, (2) cruft and the USE need not be emitted anymore,
+ or (3) hiding bugs elsewhere that are not properly representing data
+ flow. */
+
return 0;
}