[llvm-bugs] [Bug 24459] New: Incorrect code generation of conditional compares for AArch64

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=24459

            Bug ID: 24459
           Summary: Incorrect code generation of conditional compares for
                    AArch64
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: AArch64
          Assignee: unassignedbugs at nondot.org
          Reporter: kristof.beyls at gmail.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Created attachment 14725
  --> https://llvm.org/bugs/attachment.cgi?id=14725&action=edit
reduced test case

It seems that http://llvm.org/viewvc/llvm-project?view=revision&revision=242436
introduced a correctness regression.
The attached reduced test case (still not tiny though) shows that at
optimization level -O1, this code gets miscompiled, while it still was getting
compiled correctly by clang r242436.

$ ./llvm.org/cmake-build-r242435/bin/clang
./reproducer/aarch64_tree_tests_reduce.c -S -O1 -o ./reproducer/t.242435.s;
$ ./llvm.org/cmake-build-r242436/bin/clang
./reproducer/aarch64_tree_tests_reduce.c -S -O1 -o ./reproducer/t.242436.s;
$ ./llvm.org/cmake-build-r242435/bin/clang
./reproducer/aarch64_tree_tests_reduce.c -O1 -o ./reproducer/t.242435.exe;
$ ./llvm.org/cmake-build-r242436/bin/clang
./reproducer/aarch64_tree_tests_reduce.c -O1 -o ./reproducer/t.242436.exe;
$ ./reproducer/t.242435.exe
$ ./reproducer/t.242436.exe
Expected: 0000000000000000 Got: 0000000000000000

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