[patch]: Enhance rtl-dse to remove unaligned read after writes.
Paolo Bonzini
bonzini@gnu.org
Fri Jul 6 14:51:00 GMT 2007
+ target = expand_binop (new_mode, lshr_optab, new_reg,
+ GEN_INT (shift), new_reg, 1, OPTAB_DIRECT);
+
+ /* If the target is NULL, there was no way to do this, if the
+ target is not equal to new_reg, then it had to add an extra
+ move. In either case, we fall back and try the arithmetic
+ shift of this size to see if we get lucky there. */
+ if (target != new_reg)
+ target = expand_binop (new_mode, ashr_optab, new_reg,
+ GEN_INT (shift), new_reg, 1, OPTAB_DIRECT);
I guess you are missing and end_sequence/start_sequence pair to discard
the result of expanding with lshr_optab.
Paolo
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