[LinkModules] Intelligently merge triples that differ only in the minimum version number if the vendor is apple

[ahatanak]

Summary

Currently, when we merge two triples that differ only in the minimum version number, we give a warning such as:

WARNING: Linking two modules of different target triples: 'thumbv7-apple-ios8.0.0' and 'thumbv7-apple-ios3.0.0'

This patch fixes LinkModules to stop warning and pick the triple with the larger version number in such case.

rdar://problem/16743513

[• tstellarAMD]

lib/Linker/LinkModules.cpp

1501–1505

I've run into this problem too when trying to link amdgcn triples with differing operating systems (e.g. amgcn-- and amdgcn--amdhsa).

Would it be possible to move this part into a separate function like you've done for triplesMatch(), so that it could be more easily updated for other targets.

Thanks,
Tom

[ahatanak]

Address review comments.

In summary, this patch makes the following changes:

• Change ModuleLinker to stop issuing a warning when the Triple objects compare equal even when the triple strings differ.
• On Apple platforms, choose the triple that has the larger version number.

include/llvm/ADT/Triple.h

bool isOSVersionLT(unsigned Major, unsigned Minor = 0,
     if (LHS[1] != Minor)
       return LHS[1] < Minor;
     if (LHS[2] != Micro)
       return LHS[1] < Micro;
 
     return false;
   }
 
+  bool isOSVersionLT(const Triple &Other) const {
+    unsigned RHS[3];
+    Other.getOSVersion(RHS[0], RHS[1], RHS[2]);
+    return isOSVersionLT(RHS[0], RHS[1], RHS[2]);
+  }
+
   /// isMacOSXVersionLT - Comparison function for checking OS X version
   /// compatibility, which handles supporting skewed version numbering schemes
   /// used by the "darwin" triples.
   unsigned isMacOSXVersionLT(unsigned Major, unsigned Minor = 0,
                              unsigned Micro = 0) const {
     assert(isMacOSX() && "Not an OS X triple!");
 
     // If this is OS X, expect a sane version number.

lib/Linker/LinkModules.cpp

 
 #include "llvm/Linker/Linker.h"
 #include "llvm-c/Linker.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/Triple.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/TypeFinder.h"
 #include "llvm/Support/CommandLine.h"
if (!Op || Op->getOperand(2) != ReqValue) {
                           "': does not have the required value");
       continue;
     }
   }
 
   return HasErr;
 }
 
+// This function returns true if the triples match.
+static bool triplesMatch(const Triple &T0, const Triple &T1) {
+  if (T0.getVendor() != Triple::Apple)
+    return T0.str() == T1.str();
+
+  // If vendor is apple, ignore the version number.
+  return T0.getArch() == T1.getArch() && T0.getSubArch() == T1.getSubArch() &&
+      T0.getVendor() == T1.getVendor() && T0.getOS() == T1.getOS();
+}
+
 bool ModuleLinker::run() {
   assert(DstM && "Null destination module");
   assert(SrcM && "Null source module");
 
   // Inherit the target data from the source module if the destination module
   // doesn't have one already.
   if (!DstM->getDataLayout() && SrcM->getDataLayout())
     DstM->setDataLayout(SrcM->getDataLayout());
 
-  // Copy the target triple from the source to dest if the dest's is empty.
-  if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
-    DstM->setTargetTriple(SrcM->getTargetTriple());
-
   if (SrcM->getDataLayout() && DstM->getDataLayout() &&
       *SrcM->getDataLayout() != *DstM->getDataLayout()) {
     emitWarning("Linking two modules of different data layouts: '" +
                 SrcM->getModuleIdentifier() + "' is '" +
                 SrcM->getDataLayoutStr() + "' whereas '" +
                 DstM->getModuleIdentifier() + "' is '" +
                 DstM->getDataLayoutStr() + "'\n");
   }
-  if (!SrcM->getTargetTriple().empty() &&
-      DstM->getTargetTriple() != SrcM->getTargetTriple()) {
+
+  // Copy the target triple from the source to dest if the dest's is empty.
+  if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
+    DstM->setTargetTriple(SrcM->getTargetTriple());
+
+  Triple SrcTriple(SrcM->getTargetTriple()), DstTriple(DstM->getTargetTriple());
+
+  if (!SrcM->getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
     emitWarning("Linking two modules of different target triples: " +
                 SrcM->getModuleIdentifier() + "' is '" +
                 SrcM->getTargetTriple() + "' whereas '" +
                 DstM->getModuleIdentifier() + "' is '" +
                 DstM->getTargetTriple() + "'\n");
-  }
+
+  // If vendor is apple, pick the triple with the larger version number.
+  if (SrcTriple.getVendor() == Triple::Apple)
+    if (DstTriple.isOSVersionLT(SrcTriple))
+      DstM->setTargetTriple(SrcM->getTargetTriple());
 
   // Append the module inline asm string.
   if (!SrcM->getModuleInlineAsm().empty()) {
     if (DstM->getModuleInlineAsm().empty())
       DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
     else
       DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
                                SrcM->getModuleInlineAsm());

test/Linker/apple-version0.ll

+; RUN: llvm-link %s %p/apple-version1.ll -S -o - 2>%t.err | FileCheck %s -check-prefix=CHECK1
+; RUN: (echo foo ;cat %t.err) | FileCheck --check-prefix=WARN1 %s
+; RUN: llvm-link %s %p/apple-version2.ll -S -o - 2>%t.err | FileCheck %s -check-prefix=CHECK2
+; RUN: (echo foo ;cat %t.err) | FileCheck --check-prefix=WARN2 %s
+; RUN: llvm-link %s %p/apple-version3.ll -S -o /dev/null 2>%t.err
+; RUN: cat %t.err | FileCheck --check-prefix=WARN3 %s
+
+; Check that the triple that has the larger version number is chosen and no
+; warnings are issued when the triples differ only in version numbers.
+
+; CHECK1: target triple = "x86_64-apple-macosx10.10.0"
+; WARN1-NOT: WARNING
+; CHECK2: target triple = "x86_64-apple-macosx10.9.0"
+; WARN2-NOT: WARNING
+; WARN3: WARNING: Linking two modules of different target triples
+
+target triple = "x86_64-apple-macosx10.9.0"

test/Linker/apple-version1.ll

+; This file is used with apple-version0.ll
+; RUN: true
+
+target triple = "x86_64-apple-macosx10.10.0"

test/Linker/apple-version2.ll

+; This file is used with apple-version0.ll
+; RUN: true
+
+target triple = "x86_64-apple-macosx10.8.0"

test/Linker/apple-version3.ll

+; This file is used with apple-version0.ll
+; RUN: true
+
+target triple = "x86-apple-macosx10.9.0"