[llvm-bugs] [Bug 35359] New: [GlobalISel][AArch64] Calling convention for HFAs incorrect on big-endian targets

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https://bugs.llvm.org/show_bug.cgi?id=35359

            Bug ID: 35359
           Summary: [GlobalISel][AArch64] Calling convention for HFAs
                    incorrect on big-endian targets
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: GlobalISel
          Assignee: unassignedbugs at nondot.org
          Reporter: oliver.stannard at arm.com
                CC: llvm-bugs at lists.llvm.org

Global-isel generates incorrect code when targeting big-endian AArch64 for this
code:
  struct foo {
    float first;
    float second;
  };
  float get_first(foo p) {
    return p.first;
  }

This is the code that global-isel currently generates:
  // /work/llvm/build/bin/clang --target=aarch64--none-eabi -march=armv8-a -c
callees.cpp -O0 -mllvm -global-isel=true -mllvm -global-isel-abort=0
-mbig-endian -o - -S
  _Z9get_first3foo:                       // @_Z9get_first3foo
  // BB#0:                                // %entry
          sub     sp, sp, #16             // =16
                                          // implicit-def: %X8
          fmov    w9, s0
          mov     w10, w9
          bfxil   x8, x10, #0, #32
          fmov    w9, s1
          mov     w10, w9
          bfi     x8, x10, #32, #32
          add     x10, sp, #8             // =8
          str     x8, [sp, #8]
          ldr     w9, [x10]
          fmov    s0, w9
          add     sp, sp, #16             // =16
          ret

When run on a big-endian target, this incorrectly returns the second member of
the struct, instead of the first.

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