[macho] add support for emitting macho files with two build version load commands

This patch extends LLVM IR to add metadata that can be used to emit macho files with two build version load commands.
It utilizes "darwin.target_variant.triple" and "darwin.target_variant.SDK Version" metadata names for that,
which will be set by a future patch in clang.

MachO uses two build version load commands to represent an object file / binary that is targeting both the macOS target,
and the Mac Catalyst target. At runtime, a dynamic library that supports both targets can be loaded from either a native
macOS or a Mac Catalyst app on a macOS system. We want to add support to this to upstream to LLVM to be able to build
compiler-rt for both targets, to finish the complete support for the Mac Catalyst platform, which is right now targetable
by upstream clang, but the compiler-rt bits aren't supported because of the lack of this multiple build version support.

Differential Revision: https://reviews.llvm.org/D112189

1 files changed, 42 insertions, 8 deletions

diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index b0da490..b056311 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -1308,8 +1308,10 @@ getMachoBuildVersionPlatformType(const Triple &Target) {
   llvm_unreachable("unexpected OS type");
 }
 
-void MCStreamer::emitVersionForTarget(const Triple &Target,
-                                      const VersionTuple &SDKVersion) {
+void MCStreamer::emitVersionForTarget(
+    const Triple &Target, const VersionTuple &SDKVersion,
+    const Triple *DarwinTargetVariantTriple,
+    const VersionTuple &DarwinTargetVariantSDKVersion) {
   if (!Target.isOSBinFormatMachO() || !Target.isOSDarwin())
     return;
   // Do we even know the version?
@@ -1336,13 +1338,45 @@ void MCStreamer::emitVersionForTarget(const Triple &Target,
   auto LinkedTargetVersion =
       targetVersionOrMinimumSupportedOSVersion(Target, Version);
   auto BuildVersionOSVersion = getMachoBuildVersionSupportedOS(Target);
+  bool ShouldEmitBuildVersion = false;
   if (BuildVersionOSVersion.empty() ||
-      LinkedTargetVersion >= BuildVersionOSVersion)
-    return emitBuildVersion(getMachoBuildVersionPlatformType(Target),
-                            LinkedTargetVersion.getMajor(),
-                            LinkedTargetVersion.getMinor().getValueOr(0),
-                            LinkedTargetVersion.getSubminor().getValueOr(0),
-                            SDKVersion);
+      LinkedTargetVersion >= BuildVersionOSVersion) {
+    if (Target.isMacCatalystEnvironment() && DarwinTargetVariantTriple &&
+        DarwinTargetVariantTriple->isMacOSX()) {
+      emitVersionForTarget(*DarwinTargetVariantTriple,
+                           DarwinTargetVariantSDKVersion,
+                           /*TargetVariantTriple=*/nullptr,
+                           /*TargetVariantSDKVersion=*/VersionTuple());
+      emitDarwinTargetVariantBuildVersion(
+          getMachoBuildVersionPlatformType(Target),
+          LinkedTargetVersion.getMajor(),
+          LinkedTargetVersion.getMinor().getValueOr(0),
+          LinkedTargetVersion.getSubminor().getValueOr(0), SDKVersion);
+      return;
+    }
+    emitBuildVersion(getMachoBuildVersionPlatformType(Target),
+                     LinkedTargetVersion.getMajor(),
+                     LinkedTargetVersion.getMinor().getValueOr(0),
+                     LinkedTargetVersion.getSubminor().getValueOr(0),
+                     SDKVersion);
+    ShouldEmitBuildVersion = true;
+  }
+
+  if (const Triple *TVT = DarwinTargetVariantTriple) {
+    if (Target.isMacOSX() && TVT->isMacCatalystEnvironment()) {
+      auto TVLinkedTargetVersion =
+          targetVersionOrMinimumSupportedOSVersion(*TVT, TVT->getiOSVersion());
+      emitDarwinTargetVariantBuildVersion(
+          getMachoBuildVersionPlatformType(*TVT),
+          TVLinkedTargetVersion.getMajor(),
+          TVLinkedTargetVersion.getMinor().getValueOr(0),
+          TVLinkedTargetVersion.getSubminor().getValueOr(0),
+          DarwinTargetVariantSDKVersion);
+    }
+  }
+
+  if (ShouldEmitBuildVersion)
+    return;
 
   emitVersionMin(getMachoVersionMinLoadCommandType(Target),
                  LinkedTargetVersion.getMajor(),