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

Thu Feb 12 12:05:37 PST 2015

On Thu, Feb 12, 2015 at 9:47 AM, Duncan P. N. Exon Smith <
dexonsmith at apple.com> wrote:

>
> > On 2015-Feb-12, at 08:59, Tom Stellard <thomas.stellard at amd.com> wrote:
> >
> >
> >
> >
> > ================
> > Comment at: lib/Linker/LinkModules.cpp:1501-1505
> > @@ -1487,3 +1500,7 @@
> >                 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());
> >
> > ----------------
> >
> > 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.
>
> I agree with Tom.
>
> A couple of other minor points below:
>
> > Index: lib/Linker/LinkModules.cpp
> > ===================================================================
> > --- lib/Linker/LinkModules.cpp
> > +++ lib/Linker/LinkModules.cpp
> > @@ -18,6 +18,7 @@
> >  #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"
> > @@ -1457,6 +1458,16 @@
> >    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();
>
> Shouldn't this just be `return T0 == T1`?
>
>
Reading the code now, I realize the code below this line should be fixed.
My patch changes the current behavior, which is to issue a warning when the
two triple strings don't match exactly. Triple's constructor parses
different architecture strings to the same enum (e.g., "i386" and "i486"
both map to Triple::x86), so in some cases tripleMatch would return true
even when the strings don't match exactly.

> +
> > +  // 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();
>
> More generally, I might invert the logic to make this more obviously
> extensible, e.g.:
>
>     if (T0.getVender() == Triple::Apple)
>       return T0.getArch() == T1.getArch() && ...;
>
>     return T0 == T1;
>
> > +}
> > +
> >  bool ModuleLinker::run() {
> >    assert(DstM && "Null destination module");
> >    assert(SrcM && "Null source module");
> > @@ -1466,26 +1477,32 @@
> >    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()) {
> > Index: test/Linker/apple-version0.ll
> > ===================================================================
> > --- /dev/null
> > +++ test/Linker/apple-version0.ll
>
> I'd rename this `test/Linker/apple-version.ll`.  More below.
>
> > @@ -0,0 +1,17 @@
> > +; RUN: llvm-link %s %p/apple-version1.ll -S -o - 2>%t.err | FileCheck
> %s -check-prefix=CHECK1
>
> I've usually used %S here instead of %p.  I don't even see %p
> documented [1].  What's the difference?
>
> [1]: http://llvm.org/docs/TestingGuide.html#substitutions

Judging from the code in TestRunner.py, It looks like they have the same
meaning. I'm not sure why %S is documented, but %p isn't. I'll change my
test cases to use %S to avoid confusion.

>
>
> > +; RUN: (echo foo ;cat %t.err) | FileCheck --check-prefix=WARN1 %s
>
> Instead of `echo foo` you should use `FileCheck --allow-empty`.
>
> > +; 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"
> > Index: test/Linker/apple-version1.ll
> > ===================================================================
> > --- /dev/null
> > +++ test/Linker/apple-version1.ll
> > @@ -0,0 +1,4 @@
> > +; This file is used with apple-version0.ll
> > +; RUN: true
>
> Move to `test/Linker/Inputs/apple-version/1.ll` and skip the RUN
> (and the comment -- this way the paths are self-documenting).
>
> > +
> > +target triple = "x86_64-apple-macosx10.10.0"
> > Index: test/Linker/apple-version2.ll
> > ===================================================================
> > --- /dev/null
> > +++ test/Linker/apple-version2.ll
>
> `test/Linker/Inputs/apple-version/2.ll`
>
> > @@ -0,0 +1,4 @@
> > +; This file is used with apple-version0.ll
> > +; RUN: true
> > +
> > +target triple = "x86_64-apple-macosx10.8.0"
> > Index: test/Linker/apple-version3.ll
> > ===================================================================
> > --- /dev/null
> > +++ test/Linker/apple-version3.ll
>
> `test/Linker/Inputs/apple-version/3.ll`
>
> > @@ -0,0 +1,4 @@
> > +; This file is used with apple-version0.ll
> > +; RUN: true
> > +
> > +target triple = "x86-apple-macosx10.9.0"
> >
>
>
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