Messages in this thread | | | Date | Mon, 19 Aug 2019 20:15:38 -0700 | From | Nathan Chancellor <> | Subject | Re: [PATCH] powerpc: Don't add -mabi= flags when building with Clang |
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On Mon, Aug 19, 2019 at 04:19:31AM -0500, Segher Boessenkool wrote: > On Sun, Aug 18, 2019 at 12:13:21PM -0700, Nathan Chancellor wrote: > > When building pseries_defconfig, building vdso32 errors out: > > > > error: unknown target ABI 'elfv1' > > > > Commit 4dc831aa8813 ("powerpc: Fix compiling a BE kernel with a > > powerpc64le toolchain") added these flags to fix building GCC but > > clang is multitargeted and does not need these flags. The ABI is > > properly set based on the target triple, which is derived from > > CROSS_COMPILE. > > You mean that LLVM does not *allow* you to select a different ABI, or > different ABI options, you always have to use the default. (Everything > else you say is true for GCC as well).
I need to improve the wording of the commit message as it is really that clang does not allow a different ABI to be selected for 32-bit PowerPC, as the setABI function is not overridden and it defaults to false.
https://github.com/llvm/llvm-project/blob/llvmorg-9.0.0-rc2/clang/include/clang/Basic/TargetInfo.h#L1073-L1078
https://github.com/llvm/llvm-project/blob/llvmorg-9.0.0-rc2/clang/lib/Basic/Targets/PPC.h#L327-L365
GCC appears to just silently ignores this flag (I think it is the SUBSUBTARGET_OVERRIDE_OPTIONS macro in gcc/config/rs6000/linux64.h).
It can be changed for 64-bit PowerPC it seems but it doesn't need to be with clang because everything is set properly internally (I'll find a better way to clearly word that as I am sure I'm not quite getting that subtlety right).
> (-mabi= does not set a "target ABI", fwiw, it is more subtle; please see > the documentation. Unless LLVM is incompatible in that respect as well?)
Are you referring to the error message? I suppose I could file an LLVM bug report on that but that message applies to all of the '-mabi=' options, which may refer to a target ABI.
Cheers, Nathan
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