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From: "acsawdey at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/97926] ICE in patch_jump_insn, at cfgrtl.c:1298
Date: Thu, 18 Mar 2021 18:11:28 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D97926

--- Comment #3 from acsawdey at gcc dot gnu.org ---
So the underlying problem here is that the unordered comparisons are not
allowed with -ffinite-math-only due to this predicate:

;; Return 1 if OP is a comparison operation that is valid for a branch
;; instruction.  We check the opcode against the mode of the CC value.
;; validate_condition_mode is an assertion.
(define_predicate "branch_comparison_operator"
   (and (match_operand 0 "comparison_operator")
        (match_test "GET_MODE_CLASS (GET_MODE (XEXP (op, 0))) =3D=3D MODE_C=
C")
        (if_then_else (match_test "GET_MODE (XEXP (op, 0)) =3D=3D CCFPmode")
          (if_then_else (match_test "flag_finite_math_only")
            (match_code "lt,le,gt,ge,eq,ne,unordered,ordered")
            (match_code "lt,gt,eq,unordered,unge,unle,ne,ordered"))
          (match_code "lt,ltu,le,leu,gt,gtu,ge,geu,eq,ne"))
        (match_test "validate_condition_mode (GET_CODE (op),
                                              GET_MODE (XEXP (op, 0))),
                     1")))


But ubsan_instrument_float_cast() generates this:

  t =3D fold_build2 (UNLE_EXPR, boolean_type_node, expr, min);
  tt =3D fold_build2 (UNGE_EXPR, boolean_type_node, expr, max);

which eventually leads to the ICE. Even if this branch wasn't rewritten by
patch_dump_insn() it would not be recognized and would eventually ICE.

Segher is working on a change to that predicate for PR98092 though which ma=
y be
a workaround fix for this.=