https://sourceware.org/bugzilla/show_bug.cgi?id=28687
--- Comment #1 from Nikita Popov <npv1310 at gmail dot com> ---
I've verified the case by performing these steps:
1) Configure the project:
binutils-gdb$ ./configure CFLAGS='-g -O2' CXXFLAGS='-g -O2' LDFLAGS='-g -O2'
host_configargs='--disable-option-checking --disable-silent-rules'
2) Observe compilation command for dwarf1.c; slightly modify it to produce
assembly listing instead:
binutils-gdb/bfd$ gcc -DHAVE_CONFIG_H -I. -DBINDIR=\"/usr/local/bin\"
-DLIBDIR=\"/usr/local/lib\" -I. -I. -I./../include -DHAVE_x86_64_elf64_vec
-DHAVE_i386_elf32_vec -DHAVE_iamcu_elf32_vec -DHAVE_x86_64_elf32_vec
-DHAVE_i386_pei_vec -DHAVE_x86_64_pe_vec -DHAVE_x86_64_pei_vec
-DHAVE_l1om_elf64_vec -DHAVE_k1om_elf64_vec -DHAVE_elf64_le_vec
-DHAVE_elf64_be_vec -DHAVE_elf32_le_vec -DHAVE_elf32_be_vec -W -Wall
-Wstrict-prototypes -Wmissing-prototypes -Wshadow -Wstack-usage=262144 -Werror
-I./../zlib -g -O2 -S dwarf1.c -o-
3) The C fragment
268: case FORM_BLOCK4:
269: if (xptr + 4 <= aDiePtrEnd)
270: {
271: block_len = bfd_get_32 (abfd, xptr);
272: if (xptr + block_len > aDiePtrEnd
273: || xptr + block_len < xptr)
274: return false;
275: xptr += block_len;
276: }
277: xptr += 4;
278: break;
is turned into
.LVL22:
.loc 1 272 0
movl %eax, %eax
addq %rax, %r14
.LVL23:
cmpq %r14, %r12
jb .L4
.LVL24:
.L19:
.loc 1 277 0
leaq 4(%r14), %rbx
by gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
Note that the condition 'xptr + block_len < xptr' is completely omitted as is
clear from the assembly location markers.
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