@@ -424,11 +424,22 @@ def unary_undef_to_zero: GICombineRule<
424424 [{ return Helper.matchOperandIsUndef(*${root}, 1); }]),
425425 (apply [{ Helper.replaceInstWithConstant(*${root}, 0); }])>;
426426
427+ def unary_undef_to_undef_frags : GICombinePatFrag<
428+ (outs root:$dst), (ins),
429+ !foreach(op,
430+ [G_TRUNC, G_BITCAST, G_ANYEXT, G_PTRTOINT, G_INTTOPTR, G_FPTOSI,
431+ G_FPTOUI],
432+ (pattern (op $dst, $x), (G_IMPLICIT_DEF $x)))>;
433+ def unary_undef_to_undef : GICombineRule<
434+ (defs root:$dst),
435+ (match (unary_undef_to_undef_frags $dst)),
436+ (apply [{ Helper.replaceInstWithUndef(*${dst}.getParent()); }])>;
437+
427438// Instructions where if any source operand is undef, the instruction can be
428439// replaced with undef.
429440def propagate_undef_any_op: GICombineRule<
430441 (defs root:$root),
431- (match (wip_match_opcode G_ADD, G_FPTOSI, G_FPTOUI, G_SUB, G_XOR, G_TRUNC, G_BITCAST, G_ANYEXT, G_PTRTOINT, G_INTTOPTR ):$root,
442+ (match (wip_match_opcode G_ADD, G_SUB, G_XOR):$root,
432443 [{ return Helper.matchAnyExplicitUseIsUndef(*${root}); }]),
433444 (apply [{ Helper.replaceInstWithUndef(*${root}); }])>;
434445
@@ -1919,6 +1930,7 @@ def undef_combines : GICombineGroup<[undef_to_fp_zero, undef_to_int_zero,
19191930 binop_left_undef_to_zero,
19201931 binop_right_undef_to_undef,
19211932 unary_undef_to_zero,
1933+ unary_undef_to_undef,
19221934 propagate_undef_any_op,
19231935 propagate_undef_all_ops,
19241936 propagate_undef_shuffle_mask,
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