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14a627fe79
Add both asm-based and C-based tests which have 'may_goto 0' insns.
For the following code in C-based test,
int i, tmp[3];
for (i = 0; i < 3 && can_loop; i++)
tmp[i] = 0;
The clang compiler (clang 19 and 20) generates
may_goto 2
may_goto 1
may_goto 0
r1 = 0
r2 = 0
r3 = 0
The above asm codes are due to llvm pass SROAPass. This ensures the
successful verification since tmp[0-2] are initialized. Otherwise,
the code without SROAPass like
may_goto 5
r1 = 0
may_goto 3
r2 = 0
may_goto 1
r3 = 0
will have verification failure.
Although from the source code C-based test should have verification
failure, clang compiler optimization generates code with successful
verification. If gcc generates different asm codes than clang, the
following code can be used for gcc:
int i, tmp[3];
for (i = 0; i < 3; i++)
tmp[i] = 0;
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250118192034.2124952-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
29 lines
493 B
C
29 lines
493 B
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
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#include "bpf_misc.h"
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#include "bpf_experimental.h"
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int gvar;
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SEC("raw_tp")
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__description("C code with may_goto 0")
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__success
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int may_goto_c_code(void)
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{
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int i, tmp[3];
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for (i = 0; i < 3 && can_loop; i++)
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tmp[i] = 0;
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for (i = 0; i < 3 && can_loop; i++)
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tmp[i] = gvar - i;
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for (i = 0; i < 3 && can_loop; i++)
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gvar += tmp[i];
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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