------- Additional Comments From steven at gcc dot gnu dot org 2005-05-17 08:14 ------- SSA form after inserting ASSERT_EXPRs main () { int i; int c; int b; int D.1576; <bb 0>: c_4 = f (); if (c_4 <= 0) goto <L0>; else goto <L8>; <L0>:; c_8 = ASSERT_EXPR <c_4, c_4 <= 0>; c_7 = -c_8; goto <bb 3> (<L2>); <L1>:; i_5 = ASSERT_EXPR <i_2, i_2 < c_7>; i_10 = i_5 + 1; # i_2 = PHI <0(1), i_10(2)>; # b_1 = PHI <0(1), 1(2)>; <L2>:; if (i_2 < c_7) goto <L1>; else goto <L3>; <L3>:; i_9 = ASSERT_EXPR <i_2, i_2 >= c_7>; if (b_1 == 0) goto <L4>; else goto <L5>; <L4>:; abort (); <L8>:; c_3 = ASSERT_EXPR <c_4, c_4 > 0>; <L5>:; return 0; } ... Visiting statement: c_8 = ASSERT_EXPR <c_4, c_4 <= 0>; (analyze_scalar_evolution (loop_nb = 0) (scalar = c_8) (get_scalar_evolution (scalar = c_8) (scalar_evolution = )) (analyze_scalar_evolution (loop_nb = 0) (scalar = c_4) (get_scalar_evolution (scalar = c_4) (scalar_evolution = c_4)) (set_scalar_evolution (scalar = c_4) (scalar_evolution = c_4)) ) (set_scalar_evolution (scalar = c_8) (scalar_evolution = c_4)) ) Found new range [-2147483648, 0] for c_8 Visiting statement: c_7 = -c_8; (analyze_scalar_evolution (loop_nb = 0) (scalar = c_7) (get_scalar_evolution (scalar = c_7) (scalar_evolution = )) (analyze_scalar_evolution (loop_nb = 0) (scalar = c_8) (get_scalar_evolution (scalar = c_8) (scalar_evolution = c_4)) (set_scalar_evolution (scalar = c_8) (scalar_evolution = c_4)) ) (set_scalar_evolution (scalar = c_7) (scalar_evolution = -c_4)) ) Found new range [-080000000, 0] for c_7 // !?!?!?!?! ... Value ranges after VRP: b_1: [0, 0] i_2: [0, 0] c_3: [1, 2147483647] c_4: VARYING <retval>_6: VARYING c_7: [-080000000, 0] c_8: [-2147483648, 0] i_9: [c_7, 2147483647] Function after VRP: main () { int i; int c; int b; int D.1576; <bb 0>: c_4 = f (); if (c_4 <= 0) goto <L0>; else goto <L8>; <L0>:; c_8 = c_4; c_7 = -c_8; # i_2 = PHI <0(1)>; # b_1 = PHI <0(1)>; <L2>:; i_9 = i_2; abort (); <L8>:; c_3 = c_4; return 0; } This may actually be a scev bug...
-- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21332