i386.c (test splitter): Narrow tests vs paradoxical subregs.
* i386.c (test splitter): Narrow tests vs paradoxical subregs. (jcc splitters): Add two splitters to simplify compound compares that simplify_comparison can't handle. From-SVN: r46178
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@ -2,6 +2,10 @@
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* combine.c (try_combine): Handle a SEQUENCE of one insn.
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* i386.c (test splitter): Narrow tests vs paradoxical subregs.
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(jcc splitters): Add two splitters to simplify compound compares
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that simplify_comparison can't handle.
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2001-10-10 Richard Henderson <rth@redhat.com>
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* langhooks.c: Include langhooks.h.
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@ -8125,7 +8125,7 @@
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HOST_WIDE_INT len = INTVAL (operands[1]);
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HOST_WIDE_INT pos = INTVAL (operands[2]);
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HOST_WIDE_INT mask;
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enum machine_mode mode;
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enum machine_mode mode, submode;
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mode = GET_MODE (operands[0]);
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if (GET_CODE (operands[0]) == MEM)
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@ -8138,6 +8138,15 @@
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operands[0] = adjust_address (operands[0], mode, 0);
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}
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}
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else if (GET_CODE (operands[0]) == SUBREG
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&& (submode = GET_MODE (SUBREG_REG (operands[0])),
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GET_MODE_BITSIZE (mode) > GET_MODE_BITSIZE (submode))
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&& pos + len <= GET_MODE_BITSIZE (submode))
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{
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/* Narrow a paradoxical subreg to prevent partial register stalls. */
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mode = submode;
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operands[0] = SUBREG_REG (operands[0]);
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}
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else if (mode == HImode && pos + len <= 8)
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{
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/* Small HImode tests can be converted to QImode. */
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@ -12745,6 +12754,55 @@
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(const_int 0)
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(const_int 1)))])
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;; In general it is not safe to assume too much about CCmode registers,
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;; so simplify-rtx stops when it sees a second one. Under certain
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;; conditions this is safe on x86, so help combine not create
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;;
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;; seta %al
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;; testb %al, %al
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;; je Lfoo
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(define_split
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[(set (pc)
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(if_then_else (ne (match_operator 0 "ix86_comparison_operator"
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[(reg 17) (const_int 0)])
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(const_int 0))
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(label_ref (match_operand 1 "" ""))
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(pc)))]
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""
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[(set (pc)
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(if_then_else (match_dup 0)
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(label_ref (match_dup 1))
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(pc)))]
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{
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PUT_MODE (operands[0], VOIDmode);
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})
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(define_split
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[(set (pc)
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(if_then_else (eq (match_operator 0 "ix86_comparison_operator"
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[(reg 17) (const_int 0)])
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(const_int 0))
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(label_ref (match_operand 1 "" ""))
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(pc)))]
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""
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[(set (pc)
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(if_then_else (match_dup 0)
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(label_ref (match_dup 1))
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(pc)))]
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{
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rtx new_op0 = copy_rtx (operands[0]);
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operands[0] = new_op0;
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PUT_MODE (new_op0, VOIDmode);
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PUT_CODE (new_op0, REVERSE_CONDITION (GET_CODE (new_op0),
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GET_MODE (XEXP (new_op0, 0))));
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/* Make sure that (a) the CCmode we have for the flags is strong
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enough for the reversed compare or (b) we have a valid FP compare. */
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if (! ix86_comparison_operator (new_op0, VOIDmode))
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FAIL;
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})
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;; Define combination compare-and-branch fp compare instructions to use
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;; during early optimization. Splitting the operation apart early makes
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;; for bad code when we want to reverse the operation.
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