+Wed Sep 30 10:09:39 1998 Mark Mitchell <mark@markmitchell.com>
+
+ * function.c (gen_mem_addressof): If the address REG is
+ REG_USERVAR_P make the new REG be so also.
+ * loop.c (scan_loop): Apply DeMorgan's laws and add documentation
+ in an attempt to clarify slightly.
+
Wed Sep 30 09:57:40 1998 Jeffrey A Law (law@cygnus.com)
* expr.c (expand_expr): Handle COMPONENT_REF, BIT_FIELD_REF ARRAY_REF
tree decl;
{
tree type = TREE_TYPE (decl);
-
rtx r = gen_rtx_ADDRESSOF (Pmode, gen_reg_rtx (GET_MODE (reg)), REGNO (reg));
SET_ADDRESSOF_DECL (r, decl);
+ /* If the original REG was a user-variable, then so is the REG whose
+ address is being taken. */
+ REG_USERVAR_P (XEXP (r, 0)) = REG_USERVAR_P (reg);
XEXP (reg, 0) = r;
PUT_CODE (reg, MEM);
We don't know its life-span, so we can't compute the benefit. */
if (REGNO (SET_DEST (set)) >= max_reg_before_loop)
;
- /* In order to move a register, we need to have one of three cases:
- (1) it is used only in the same basic block as the set
- (2) it is not a user variable and it is not used in the
- exit test (this can cause the variable to be used
- before it is set just like a user-variable).
- (3) the set is guaranteed to be executed once the loop starts,
- and the reg is not used until after that. */
- else if (! ((! maybe_never
- && ! loop_reg_used_before_p (set, p, loop_start,
- scan_start, end))
- || (! REG_USERVAR_P (SET_DEST (set))
- && ! REG_LOOP_TEST_P (SET_DEST (set)))
- || reg_in_basic_block_p (p, SET_DEST (set))))
+ else if (/* The set is a user-variable or it is used in
+ the exit test (this can cause the variable to be
+ used before it is set just like a
+ user-variable)... */
+ (REG_USERVAR_P (SET_DEST (set))
+ || REG_LOOP_TEST_P (SET_DEST (set)))
+ /* And the set is not guaranteed to be executed one
+ the loop starts, or the value before the set is
+ needed before the set occurs... */
+ && (maybe_never
+ || loop_reg_used_before_p (set, p, loop_start,
+ scan_start, end))
+ /* And the register is used in basic blocks other
+ than the one where it is set (meaning that
+ something after this point in the loop might
+ depend on its value before the set). */
+ && !reg_in_basic_block_p (p, SET_DEST (set)))
+ /* It is unsafe to move the set. The fact that these
+ three conditions are considered in conjunction means
+ that we are assuming various conditions, such as:
+
+ o It's OK to move a set of a variable which was not
+ created by the user and is not used in an exit test
+ even if that point in the set would not be reached
+ during execution of the loop. */
;
else if ((tem = invariant_p (src))
&& (dependencies == 0