[Bug rtl-optimization/94873] New: [8/9/10 Regression] wrong code with -O -fno-merge-constants -fno-split-wide-types -fno-tree-fre

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94873

            Bug ID: 94873
           Summary: [8/9/10 Regression] wrong code with -O
                    -fno-merge-constants -fno-split-wide-types
                    -fno-tree-fre
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: aarch64-unknown-linux-gnu

Created attachment 48416
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48416&action=edit
reduced testcase

Output:
$ aarch64-unknown-linux-gnu-gcc -O -fno-merge-constants -fno-split-wide-types
-fno-tree-fre testcase.c -static
$ ./a.out 
`�+%��@�

The generated code passes wrong data as the "format" argument; I wasn't able to
reproduce this without using __builtin_printf() quickly.

...
        and     w1, w1, 255     //, MEM[(volatile unsigned char *)&x]
        adrp    x0, .LANCHOR0   // tmp98,
        add     x0, x0, :lo12:.LANCHOR0 //, tmp98,
        bl      printf          //
...
        .set    .LANCHOR0,. + 0
.LC0:
        .xword  -846514461162629792
        .xword  0
.LC1:
        .string "%02x"
...

$ aarch64-unknown-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-aarch64/bin/aarch64-unknown-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r10-8064-20200430095601-g31e6f829336-checking-yes-rtl-df-extra-aarch64/bin/../libexec/gcc/aarch64-unknown-linux-gnu/10.0.1/lto-wrapper
Target: aarch64-unknown-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-cloog --with-ppl --with-isl
--with-sysroot=/usr/aarch64-unknown-linux-gnu --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=aarch64-unknown-linux-gnu
--with-ld=/usr/bin/aarch64-unknown-linux-gnu-ld
--with-as=/usr/bin/aarch64-unknown-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r10-8064-20200430095601-g31e6f829336-checking-yes-rtl-df-extra-aarch64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.0.1 20200430 (experimental) (GCC)