ICE on Android/ARM, related to recent LTO change in master

[joakim-noah]

I've been building natively on Android/ARM with the latest llvm 3.9.0 release, I ran into this ICE when building druntime synced against latest master:

LLVM ERROR: Cannot select: 0xb592b708: f64 = bitcast 0xb592b3f0
  0xb592b3f0: i64 = build_pair 0xb592b090, 0xb592b5e8
    0xb592b090: i32,ch = CopyFromReg 0xb597de18, Register:i32 %vreg16
      0xb592b1b0: i32 = Register %vreg16
    0xb592b5e8: i32,ch = CopyFromReg 0xb592b090:1, Register:i32 %vreg17
      0xb592b0d8: i32 = Register %vreg17
In function: _d_array_init_double

I bisected and found that the issue is #1811, reverting that patch has master passing all stdlib and dmd tests again (there's an unrelated failure in the dmd testsuite because of the recently added test16225, which adds the -m64 flag and doesn't work because I don't compile in the ARM64 backend on ARM32).

This is the command run on my Android tablet, same as on any other platform:

/data/data/com.termux/files/home/ldc/build71/bin/ldc2 --output-o -c -I/data/data/com.termux/files/home/ldc/runtime/druntime/src -I/data/data/com.termux/files/home/ldc/runtime/druntime/src/gc /data/data/com.termux/files/home/ldc/runtime/druntime/src/ldc/arrayinit.d -of/data/data/com.termux/files/home/ldc/build71/runtime/src/ldc/arrayinit-unittest.o -w -O3 -release -unittest -disable-invariants

You should be able to reproduce by using an ldc compiled against llvm with an ARM backend and adding the flag -mtriple=armv7-none-linux-android or -mtriple=armv7-unknown-linux-gnueabi. If not, let me know.

[JohanEngelen]

What if you comment-out setting the "use-soft-float" attribute? It wasn't clear to me how to set it for the SoftFP ABI type.

[joakim-noah]

Yeah, commenting that line out fixes it and gets all stdlib tests passing again.

[JohanEngelen]

Thanks for testing, so now I have to figure out how to set things correctly for ARM. Perhaps an extra setting is needed. I'll have a look at what clang generates for the triples you specified.

[JohanEngelen]

I think I've fixed it in #1863 . Sorry for breaking things, it's an underdocumented part of LLVM :(

[joakim-noah]

Fixed by #1863.

[lyrachord]

Follow guides at https://wiki.dlang.org/Build_D_for_Android
cmake 3.9.6/3.10.0-rc5
NDK 16
ninja 1.8.2
ldc2 1.5.0

ldc-build-runtime --reset --ninja --targetPreset=Android-arm failed

LLVM ERROR: Cannot select: 0x1a81f10fb40: f64 = bitcast 0x1a81f10f458
0x1a81f10f458: i64 = build_pair 0x1a81f10f590, 0x1a81f10f250
0x1a81f10f590: i32,ch = CopyFromReg 0x1a81f37dfd8, Register:i32 %vreg16
0x1a81f10fce0: i32 = Register %vreg16
0x1a81f10f250: i32,ch = CopyFromReg 0x1a81f10f590:1, Register:i32 %vreg17
0x1a81f10f5f8: i32 = Register %vreg17
In function: _d_array_init_double

Any advice?

Thanks

[lyrachord]

see #2406