re PR target/11087 (gcc miscompiles raid1.c from linux kernel)
PR target/11087 * loop.c (basic_induction_var): Check if convert_modes emitted any instructions. Remove them and return 0 if so. * gcc.c-torture/execute/20030717-1.c: New test. From-SVN: r69552
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@ -1,3 +1,9 @@
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2003-07-17 Jakub Jelinek <jakub@redhat.com>
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PR target/11087
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* loop.c (basic_induction_var): Check if convert_modes emitted any
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instructions. Remove them and return 0 if so.
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2003-07-18 Eric Botcazou <ebotcazou@libertysurf.fr>
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PR optimization/11083
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33
gcc/loop.c
33
gcc/loop.c
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@ -6197,7 +6197,7 @@ basic_induction_var (const struct loop *loop, rtx x, enum machine_mode mode,
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{
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enum rtx_code code;
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rtx *argp, arg;
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rtx insn, set = 0;
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rtx insn, set = 0, last, inc;
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code = GET_CODE (x);
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*location = NULL;
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@ -6225,7 +6225,26 @@ basic_induction_var (const struct loop *loop, rtx x, enum machine_mode mode,
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if (loop_invariant_p (loop, arg) != 1)
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return 0;
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*inc_val = convert_modes (GET_MODE (dest_reg), GET_MODE (x), arg, 0);
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/* convert_modes can emit new instructions, e.g. when arg is a loop
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invariant MEM and dest_reg has a different mode.
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These instructions would be emitted after the end of the function
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and then *inc_val would be an unitialized pseudo.
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Detect this and bail in this case.
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Other alternatives to solve this can be introducing a convert_modes
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variant which is allowed to fail but not allowed to emit new
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instructions, emit these instructions before loop start and let
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it be garbage collected if *inc_val is never used or saving the
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*inc_val initialization sequence generated here and when *inc_val
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is going to be actually used, emit it at some suitable place. */
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last = get_last_insn ();
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inc = convert_modes (GET_MODE (dest_reg), GET_MODE (x), arg, 0);
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if (get_last_insn () != last)
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{
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delete_insns_since (last);
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return 0;
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}
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*inc_val = inc;
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*mult_val = const1_rtx;
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*location = argp;
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return 1;
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@ -6306,7 +6325,15 @@ basic_induction_var (const struct loop *loop, rtx x, enum machine_mode mode,
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&& GET_MODE_CLASS (mode) != MODE_CC)
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{
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/* Possible bug here? Perhaps we don't know the mode of X. */
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*inc_val = convert_modes (GET_MODE (dest_reg), mode, x, 0);
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last = get_last_insn ();
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inc = convert_modes (GET_MODE (dest_reg), mode, x, 0);
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if (get_last_insn () != last)
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{
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delete_insns_since (last);
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return 0;
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}
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*inc_val = inc;
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*mult_val = const0_rtx;
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return 1;
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}
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@ -1,3 +1,8 @@
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2003-07-17 Jakub Jelinek <jakub@redhat.com>
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PR target/11087
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* gcc.c-torture/execute/20030717-1.c: New test.
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2003-07-18 Eric Botcazou <ebotcazou@libertysurf.fr>
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* g++.dg/opt/cfg1.C: New test.
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@ -0,0 +1,69 @@
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/* PR target/11087
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This testcase was miscompiled on ppc64, because basic_induction_var called
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convert_modes, yet did not expect it to emit any new instructions.
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Those were emitted at the end of the function and destroyed during life
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analysis, while the program used uninitialized pseudos created by
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convert_modes. */
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struct A
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{
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unsigned short a1;
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unsigned long a2;
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};
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struct B
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{
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int b1, b2, b3, b4, b5;
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};
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struct C
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{
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struct B c1[1];
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int c2, c3;
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};
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static
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int foo (int x)
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{
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return x < 0 ? -x : x;
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}
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int bar (struct C *x, struct A *y)
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{
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int a = x->c3;
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const int b = y->a1 >> 9;
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const unsigned long c = y->a2;
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int d = a;
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unsigned long e, f;
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f = foo (c - x->c1[d].b4);
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do
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{
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if (d <= 0)
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d = x->c2;
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d--;
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e = foo (c-x->c1[d].b4);
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if (e < f)
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a = d;
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}
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while (d != x->c3);
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x->c1[a].b4 = c + b;
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return a;
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}
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int
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main ()
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{
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struct A a;
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struct C b;
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int c;
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a.a1 = 512;
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a.a2 = 4242;
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__builtin_memset (&b, 0, sizeof (b));
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b.c1[0].b3 = 424242;
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b.c2 = 1;
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c = bar (&b, &a);
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return 0;
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}
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