In D100148#2683748, @glaubitz wrote:

Understood. However, I'm not really sure what else we need. Do we just take the architecture definition from here to pass the proper flags to the compiler or do we also need to add
some x32-specific code?

In D100148#2683325, @glaubitz wrote:

Hi! Can we get this patch merged as-is or do we need anything else?

Ah, that looks at first glance like not a compiler-rt problem but a clang problem, it will need to be taught the correct target name for x32 as well. If I'm right, that should be easy to fix, I can take a look later today or tomorrow.

I think x32 is not really supported by compiler-rt.

Does this change mean the various *_SUPPORTED_ARCH need updating to list x32 as supported too, or are those handled separately?

In D52050#2663205, @glaubitz wrote:

I think, however, we should bump the rest of the paths to 10.2.0 if possible.

I have also updated the summary to provide a more complete explanation of the changes, and hope the revised summary will answer @MaskRay's questions.

In D52050#2662570, @glaubitz wrote:

Since I am a big fan of consistency, I would rather leave it as is (4.6) and then bump to 10.2.0 in a follow-up commit.

In D52050#2662372, @MaskRay wrote:

Mostly looks good.

clang/test/Driver/Inputs/basic_cross_linux_tree/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.0/x32/crtbegin.o

Worth bumping the version. 4.6 is quite old and as a host compiler llvm-project has stopped supporting it. The distributions having 4.6 are all end-of-life.
Using a new version (matching your reality) can give impression that the user who contributed the original code may still need it for a while (say 5 years).

Tests now updated differently, avoiding the need to explicitly list libx32 as an allowed libdir. In clang/test/Preprocessor/iwithprefix.c's case, for the purposes of the test, it is not necessary to look at what appears before /clang/. In the other tests, it is possible to capture the -resource-dir string and use that.

This updates the diff as described, plus includes test suite changes needed to make check-clang pass. The changes to clang/test/Driver/Inputs/basic_cross_linux_tree/usr are because we now correctly detect that a x86_64 GCC directory that does not include x32 files cannot be used to target x32.

Feel free to update the diff here with your suggested patch.

If that were the reason, why are we not using the last GPLv2 version of config.guess, rather than the one that we happened to use back when we had an autoconf build system?

I think the problem is actually the other thing covered before (don't provide un-normalised triples as cmake arguments), though the wrong detection of LLVM_HOST_TRIPLE will cause other issues too. If we would just update config.guess, the default configuration (not specifying either LLVM_HOST_TRIPLE or LLVM_DEFAULT_TARGET_TRIPLE) should work much better; I have created D99625 for that.

I am building with

I am testing the below, on top of c8e56f394af0b9e32c413d62a0e7aebbba3e6b70, both in a Debian chroot and in my non-Debian system. Initial testing in the Debian chroot suggests that this works for simple cases, clang has no problem finding /usr/lib/gcc/x86_64-linux-gnux32/10, and also picks up the right crt*.o files when using -m32 or -m64. Will do more extensive testing.

--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -2106,7 +2106,10 @@ void Generic_GCC::GCCInstallationDetector::AddDefaultGCCPrefixes(
       "x86_64-manbo-linux-gnu", "x86_64-linux-gnu",
       "x86_64-slackware-linux", "x86_64-unknown-linux",
       "x86_64-amazon-linux",    "x86_64-linux-android"};
-  static const char *const X32LibDirs[] = {"/libx32"};
+  static const char *const X32Triples[] = {
+      "x86_64-linux-gnux32",    "x86_64-unknown-linux-gnux32",
+      "x86_64-pc-linux-gnux32"};
+  static const char *const X32LibDirs[] = {"/libx32", "/lib"};
   static const char *const X86LibDirs[] = {"/lib32", "/lib"};
   static const char *const X86Triples[] = {
       "i586-linux-gnu",     "i686-linux-gnu",
@@ -2337,17 +2340,19 @@ void Generic_GCC::GCCInstallationDetector::AddDefaultGCCPrefixes(
     TripleAliases.append(begin(AVRTriples), end(AVRTriples));
     break;
   case llvm::Triple::x86_64:
-    LibDirs.append(begin(X86_64LibDirs), end(X86_64LibDirs));
-    TripleAliases.append(begin(X86_64Triples), end(X86_64Triples));
-    // x32 is always available when x86_64 is available, so adding it as
-    // secondary arch with x86_64 triples
     if (TargetTriple.getEnvironment() == llvm::Triple::GNUX32) {
-      BiarchLibDirs.append(begin(X32LibDirs), end(X32LibDirs));
+      LibDirs.append(begin(X32LibDirs), end(X32LibDirs));
+      TripleAliases.append(begin(X32Triples), end(X32Triples));
+      BiarchLibDirs.append(begin(X86_64LibDirs), end(X86_64LibDirs));
       BiarchTripleAliases.append(begin(X86_64Triples), end(X86_64Triples));
     } else {
-      BiarchLibDirs.append(begin(X86LibDirs), end(X86LibDirs));
-      BiarchTripleAliases.append(begin(X86Triples), end(X86Triples));
+      LibDirs.append(begin(X86_64LibDirs), end(X86_64LibDirs));
+      TripleAliases.append(begin(X86_64Triples), end(X86_64Triples));
+      BiarchLibDirs.append(begin(X32LibDirs), end(X32LibDirs));
+      BiarchTripleAliases.append(begin(X32Triples), end(X32Triples));
     }
+    BiarchLibDirs.append(begin(X86LibDirs), end(X86LibDirs));
+    BiarchTripleAliases.append(begin(X86Triples), end(X86Triples));
     break;
   case llvm::Triple::x86:
     LibDirs.append(begin(X86LibDirs), end(X86LibDirs));
@@ -2357,6 +2362,8 @@ void Generic_GCC::GCCInstallationDetector::AddDefaultGCCPrefixes(
       TripleAliases.append(begin(X86Triples), end(X86Triples));
       BiarchLibDirs.append(begin(X86_64LibDirs), end(X86_64LibDirs));
       BiarchTripleAliases.append(begin(X86_64Triples), end(X86_64Triples));
+      BiarchLibDirs.append(begin(X32LibDirs), end(X32LibDirs));
+      BiarchTripleAliases.append(begin(X32Triples), end(X32Triples));
     }
     break;
   case llvm::Triple::m68k:

I may be missing something, but I do not understand the problem. What systems, other than Debian multi-arch, are you looking to also add support for? My own native x32 system uses (/usr)/libx32 for x32 libraries. Debian uses (/usr)/lib/x86_64-linux-gnux32. I can understand if some people might use (/usr)/lib without any x32 suffix, though I am not aware of anyone doing this. Where does lib32 come from, though? What other systems are you trying to account for?

In D91913#2526866, @dmajor wrote:

If I'm reading git correctly, the change is still present on the 12.x branch. Should it be reverted there too?

In D91913#2526403, @rnk wrote:

Anyway, I apologize for the misunderstanding. I'm doing my best to operate in good faith with LLVM project policies. Hopefully you feel that you have a path forward here.

In D91913#2526117, @rsmith wrote:

I think @rnk's observation that __VA_OPT__ isn't actually available in any compilation mode other than C++20 (which I hadn't previously realized) is important here: we'd left longstanding users of this functionality with no path forward, and that is, I think, sufficient motivation for a revert.

@rnk Taking it upon yourself to revert this without approval and without communication on all branches, especially given the earlier suggestion by @rsmith to only revert this on the LLVM 12 branch, is an abuse of your commit privileges as far as I am concerned. This is not a Google project. Google does not get to unilaterally dictate its direction. I do not intend to get into a revert-the-revert war and will not revert your revert myself. I do expect you to do so.

Restoring the old behaviour for clang 12 may or may not help the Chrome/Chromium people: if they also regularly build with clang from git, they would need to handle this change anyway. However, if it does help, then it sounds like a good idea to me.

In D91913#2521031, @thakis wrote:

We (and every other project out there) needs some incremental rollout plan for this.

In D91913#2520432, @zequanwu wrote:

In D91913#2520414, @hvdijk wrote:

In D91913#2520399, @zequanwu wrote:

This change also breaks many chrome ToT bots(not just windows bot), example build: https://ci.chromium.org/ui/p/chrome/builders/ci/ToTLinuxOfficial/10524/steps?succeeded=true&debug=false

That requires an account to see.

This should be accessible without an account: https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8857139118288337920/+/steps/compile/0/stdout

In D91913#2520399, @zequanwu wrote:

This change also breaks many chrome ToT bots(not just windows bot), example build: https://ci.chromium.org/ui/p/chrome/builders/ci/ToTLinuxOfficial/10524/steps?succeeded=true&debug=false

Okay, GCC enables the standards-mandated behaviour with -std=c++17 -fms-extensions as well, but GCC doesn't have any -fms-compatibility option to compare. It makes sense to me for clang -std=c++17 -fms-compatibility to match MSVC, and MSVC supports this GCC extension even in those cases where it conflicts with the standard, so I'll try to submit a patch to restore this, conditional on -fms-compatibility, later today.

In D91913#2520244, @dmajor wrote:

We have a downstream build break due to this commit. One of our files has some convoluted arg-counting logic that now returns a different count, which does not match gcc: https://godbolt.org/z/W8caMr (Note: At time of writing, the clang trunk on godbolt doesn't yet have this change.)

In D91913#2518448, @rsmith wrote:

Looks like this change matches the behavior of GCC all the way back to at least GCC 4.1.

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In D52050#2466874, @glaubitz wrote:

However, that's not the same as whether we're on an x86_64 system or on an x32 system determines which GNU triplet to use and which include and library search paths are our primary ones.

Ping 2

In D93561#2463891, @MaskRay wrote:

The lld/test/ELF tests need fixing (check-lld-elf)

Merge ELF/got-relaxed-rex.s into X86/gotpcrelx.s, update lld/test/ELF/x86-64-gotpc-relax-nopic.s.

I accidentally pushed this with the original commit message as 2aae2136, causing a missing link to/from this review. Manually linking this here now.

Be consistent in CHECK lines.

Rename parameter, split addl/leal check in two.

Rebase again, taking the X64 changes out of the diff.

In D93160#2450846, @RKSimon wrote:

rebase?

In D93160#2450356, @RKSimon wrote:

Its OK to commit the asm.py / update_llc_test_checks.py changes right away to split them from the rest of this patch

I've been able to check what Ubuntu 20.10 offers in terms of x32 support. Its kernel supports x32 binaries, it provides x32 versions of core system libraries in separate packages (e.g. libc6-x32, libx32stdc++6, libx32z1), and it provides a compiler that targets x32 by default (gcc-x86-64-linux-gnux32). These Ubuntu packages do not use the Debian/Ubuntu multiarch approach: the packages are completely independent of the corresponding x64 and i386 versions with separate names, and nothing in Ubuntu installs any libraries into any /lib/x86_64-linux-gnux32-like path. They are intended to allow x32 cross compilation on an Ubuntu system, not intended to act as a basis for running an x32 Ubuntu system. This appears to be very different from Debian's x32 support. That said, cross-compiled binaries do run on Ubuntu and it should be possible to build an x32-native LLVM with the Ubuntu-provided toolchain.

Renamed is* parameters to Is*.

Ping

In D52050#2428735, @glaubitz wrote:

Hmm, I was pretty sure that autoconf can deal with x32 inside an x32 chroot.

In D52050#2428693, @glaubitz wrote:

Maybe sys::getDefaultTargetTriple() needs to be adjusted. I'll have a look.

In D52050#2428560, @glaubitz wrote:

Any idea how it could make clang default to -mx32 if this condition is met: getToolChain().getTriple().getEnvironment() == llvm::Triple::GNUX32?

In D91338#2421852, @pengfei wrote:

I'm OK with this patch. Can you please check if expensive check is happy with it?