combine.c (simplify_set): Don't move a subreg in SET_SRC to SET_DEST if...
* combine.c (simplify_set): Don't move a subreg in SET_SRC to SET_DEST if WORD_REGISTER_OPERATIONS is not defined. From-SVN: r67388
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@ -1,3 +1,8 @@
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2003-06-03 Kazu Hirata <kazu@cs.umass.edu>
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* combine.c (simplify_set): Don't move a subreg in SET_SRC to
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SET_DEST if WORD_REGISTER_OPERATIONS is not defined.
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2003-06-03 Nathanael Nerode <neroden@gcc.gnu.org>
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* config/i386/x86-64.h: Remove two target-independent comments;
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@ -5238,17 +5238,18 @@ simplify_set (x)
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SUBST (SET_SRC (x), src);
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}
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#ifdef WORD_REGISTER_OPERATIONS
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/* If we have (set x (subreg:m1 (op:m2 ...) 0)) with OP being some operation,
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and X being a REG or (subreg (reg)), we may be able to convert this to
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(set (subreg:m2 x) (op)).
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We can always do this if M1 is narrower than M2 because that means that
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we only care about the low bits of the result.
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On a machine where WORD_REGISTER_OPERATIONS is defined, this
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transformation is safe as long as M1 and M2 have the same number
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of words.
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However, on machines without WORD_REGISTER_OPERATIONS defined, we cannot
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perform a narrower operation than requested since the high-order bits will
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be undefined. On machine where it is defined, this transformation is safe
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as long as M1 and M2 have the same number of words. */
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However, on a machine without WORD_REGISTER_OPERATIONS defined,
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we cannot apply this transformation because it would create a
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paradoxical subreg in SET_DEST. */
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if (GET_CODE (src) == SUBREG && subreg_lowpart_p (src)
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&& GET_RTX_CLASS (GET_CODE (SUBREG_REG (src))) != 'o'
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@ -5256,10 +5257,6 @@ simplify_set (x)
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/ UNITS_PER_WORD)
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== ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (src)))
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+ (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))
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#ifndef WORD_REGISTER_OPERATIONS
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&& (GET_MODE_SIZE (GET_MODE (src))
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< GET_MODE_SIZE (GET_MODE (SUBREG_REG (src))))
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#endif
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#ifdef CANNOT_CHANGE_MODE_CLASS
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&& ! (GET_CODE (dest) == REG && REGNO (dest) < FIRST_PSEUDO_REGISTER
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&& REG_CANNOT_CHANGE_MODE_P (REGNO (dest),
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@ -5277,6 +5274,7 @@ simplify_set (x)
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src = SET_SRC (x), dest = SET_DEST (x);
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}
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#endif
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#ifdef HAVE_cc0
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/* If we have (set (cc0) (subreg ...)), we try to remove the subreg
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