<div dir="ltr">Thanks!<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Apr 21, 2015 at 9:14 PM, Duncan P. N. Exon Smith <span dir="ltr"><<a href="mailto:dexonsmith@apple.com" target="_blank">dexonsmith@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">LGTM. Committed in r235472 and r235473.<br>
<div><div class="h5"><br>
> On 2015 Apr 21, at 18:05, Luqman Aden <<a href="mailto:me%2Bllvm@luqman.ca">me+llvm@luqman.ca</a>> wrote:<br>
><br>
> Whoops, update one of the testcases to make sure it actually makes.<br>
><br>
> On Tue, Apr 21, 2015 at 5:31 PM, Luqman Aden <<a href="mailto:me%2Bllvm@luqman.ca">me+llvm@luqman.ca</a>> wrote:<br>
><br>
><br>
> On Tue, Apr 21, 2015 at 3:42 PM, Duncan P. N. Exon Smith <<a href="mailto:dexonsmith@apple.com">dexonsmith@apple.com</a>> wrote:<br>
><br>
> > On 2015-Apr-20, at 15:07, Luqman Aden <<a href="mailto:me%2Bllvm@luqman.ca">me+llvm@luqman.ca</a>> wrote:<br>
> ><br>
> ><br>
> ><br>
> > On Mon, Apr 20, 2015 at 1:59 PM, Duncan P. N. Exon Smith <<a href="mailto:dexonsmith@apple.com">dexonsmith@apple.com</a>> wrote:<br>
> ><br>
> > > On 2015-Apr-20, at 13:28, Luqman Aden <<a href="mailto:me%2Bllvm@luqman.ca">me+llvm@luqman.ca</a>> wrote:<br>
> > ><br>
> > > From df1b11c561dc826d8e4836b9e910ac75185bcf05 Mon Sep 17 00:00:00 2001<br>
> > > From: Luqman Aden <<a href="mailto:luqman@apple.com">luqman@apple.com</a>><br>
> > > Date: Wed, 15 Apr 2015 12:22:32 -0700<br>
> > > Subject: [PATCH] llvm-link: Add -override flag to prefer one of a duplicate<br>
> > > symbol.<br>
> > ><br>
> > > ---<br>
> > > include/llvm/Linker/Linker.h | 4 +++-<br>
> > > lib/Linker/LinkModules.cpp | 20 +++++++++++++++----<br>
> > > test/tools/llvm-link/Inputs/foo.ll | 4 ++++<br>
> > > test/tools/llvm-link/hello.ll | 20 +++++++++++++++++++<br>
> > > test/tools/llvm-link/lit.local.cfg | 1 +<br>
> > > tools/llvm-link/llvm-link.cpp | 40 ++++++++++++++++++++++++--------------<br>
> > > 6 files changed, 69 insertions(+), 20 deletions(-)<br>
> > > create mode 100644 test/tools/llvm-link/Inputs/foo.ll<br>
> > > create mode 100644 test/tools/llvm-link/hello.ll<br>
> > > create mode 100644 test/tools/llvm-link/lit.local.cfg<br>
> > ><br>
> ><br>
> > > From df1b11c561dc826d8e4836b9e910ac75185bcf05 Mon Sep 17 00:00:00 2001<br>
> > > From: Luqman Aden <<a href="mailto:luqman@apple.com">luqman@apple.com</a>><br>
> > > Date: Wed, 15 Apr 2015 12:22:32 -0700<br>
> > > Subject: [PATCH] llvm-link: Add -override flag to prefer one of a duplicate<br>
> > > symbol.<br>
> ><br>
> > Luqman and I talked in person, and he added some context for this (seems<br>
> > to still be missing from llvm-commits?). The idea is to support an LLVM<br>
> > developer workflow where a subset of the module is extracted to a side<br>
> > module to be manipulated or optimized differently. Sometime before<br>
> > CodeGen, these functions are merged back in, and should replace the<br>
> > copies in the "main" module (regardless of IR linkage types).<br>
> ><br>
> > This seems like a pretty useful debugging workflow to me, and the<br>
> > approach in this patch seems about right.<br>
> ><br>
> > @Rafael, I'd appreciate your opinion on this.<br>
> ><br>
> > ><br>
> > > ---<br>
> > > include/llvm/Linker/Linker.h | 4 +++-<br>
> > > lib/Linker/LinkModules.cpp | 20 +++++++++++++++----<br>
> > > test/tools/llvm-link/Inputs/foo.ll | 4 ++++<br>
> > > test/tools/llvm-link/hello.ll | 20 +++++++++++++++++++<br>
> > > test/tools/llvm-link/lit.local.cfg | 1 +<br>
> > > tools/llvm-link/llvm-link.cpp | 40 ++++++++++++++++++++++++--------------<br>
> > > 6 files changed, 69 insertions(+), 20 deletions(-)<br>
> > > create mode 100644 test/tools/llvm-link/Inputs/foo.ll<br>
> > > create mode 100644 test/tools/llvm-link/hello.ll<br>
> > > create mode 100644 test/tools/llvm-link/lit.local.cfg<br>
> > ><br>
> > > diff --git a/include/llvm/Linker/Linker.h b/include/llvm/Linker/Linker.h<br>
> > > index 5ca815c..c43b90e 100644<br>
> > > --- a/include/llvm/Linker/Linker.h<br>
> > > +++ b/include/llvm/Linker/Linker.h<br>
> > > @@ -68,8 +68,10 @@ public:<br>
> > > void deleteModule();<br>
> > ><br>
> > > /// \brief Link \p Src into the composite. The source is destroyed.<br>
> > > + /// Passing OverrideSymbols as true will have symbols from Src<br>
> > > + /// shadow those in the Dest.<br>
> > > /// Returns true on error.<br>
> > > - bool linkInModule(Module *Src);<br>
> > > + bool linkInModule(Module *Src, bool OverrideSymbols = false);<br>
> > ><br>
> > > /// \brief Set the composite to the passed-in module.<br>
> > > void setModule(Module *Dst);<br>
> > > diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp<br>
> > > index 21edc50..3a46a33 100644<br>
> > > --- a/lib/Linker/LinkModules.cpp<br>
> > > +++ b/lib/Linker/LinkModules.cpp<br>
> > > @@ -424,12 +424,17 @@ class ModuleLinker {<br>
> > ><br>
> > > DiagnosticHandlerFunction DiagnosticHandler;<br>
> > ><br>
> > > + /// For symbol clashes, prefer those from Src.<br>
> > > + bool OverrideFromSrc;<br>
> > > +<br>
> > > public:<br>
> > > ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,<br>
> > > - DiagnosticHandlerFunction DiagnosticHandler)<br>
> > > + DiagnosticHandlerFunction DiagnosticHandler,<br>
> > > + bool Override = false)<br>
> ><br>
> > Why spell this differently from the class member?<br>
> ><br>
> > Also, are there any callers that don't specify this flag? If not, don't<br>
> > provide a default.<br>
> ><br>
> > Updated.<br>
> ><br>
> ><br>
> > > : DstM(dstM), SrcM(srcM), TypeMap(Set),<br>
> > > ValMaterializer(TypeMap, DstM, LazilyLinkGlobalValues),<br>
> > > - DiagnosticHandler(DiagnosticHandler) {}<br>
> > > + DiagnosticHandler(DiagnosticHandler),<br>
> > > + OverrideFromSrc(Override) {}<br>
> > ><br>
> > > bool run();<br>
> > ><br>
> > > @@ -725,6 +730,12 @@ bool ModuleLinker::getComdatResult(const Comdat *SrcC,<br>
> > > bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,<br>
> > > const GlobalValue &Dest,<br>
> > > const GlobalValue &Src) {<br>
> > > + // Should we unconditionally use the Src?<br>
> > > + if (OverrideFromSrc) {<br>
> > > + LinkFromSrc = true;<br>
> > > + return false;<br>
> > > + }<br>
> > > +<br>
> > > // We always have to add Src if it has appending linkage.<br>
> > > if (Src.hasAppendingLinkage()) {<br>
> > > LinkFromSrc = true;<br>
> > > @@ -794,6 +805,7 @@ bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,<br>
> > > assert(!Dest.hasExternalWeakLinkage());<br>
> > > assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&<br>
> > > "Unexpected linkage type!");<br>
> > > +<br>
> ><br>
> > This seems unrelated to the patch?<br>
> ><br>
> > Yes, whitespace left over from debugging before. I've now removed it.<br>
> ><br>
> ><br>
> > > return emitError("Linking globals named '" + Src.getName() +<br>
> > > "': symbol multiply defined!");<br>
> > > }<br>
> > > @@ -1742,9 +1754,9 @@ void Linker::deleteModule() {<br>
> > > Composite = nullptr;<br>
> > > }<br>
> > ><br>
> > > -bool Linker::linkInModule(Module *Src) {<br>
> > > +bool Linker::linkInModule(Module *Src, bool OverrideSymbols) {<br>
> > > ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,<br>
> > > - DiagnosticHandler);<br>
> > > + DiagnosticHandler, OverrideSymbols);<br>
> > > bool RetCode = TheLinker.run();<br>
> > > Composite->dropTriviallyDeadConstantArrays();<br>
> > > return RetCode;<br>
> > > diff --git a/test/tools/llvm-link/Inputs/foo.ll b/test/tools/llvm-link/Inputs/foo.ll<br>
> > > new file mode 100644<br>
> > > index 0000000..6e06fa5<br>
> > > --- /dev/null<br>
> > > +++ b/test/tools/llvm-link/Inputs/foo.ll<br>
> > > @@ -0,0 +1,4 @@<br>
> > > +define i32 @foo(i32 %i) {<br>
> > > +entry:<br>
> > > + ret i32 4<br>
> > > +}<br>
> ><br>
> > We usually put lib/Linker tests in "test/Linker".<br>
> ><br>
> > > diff --git a/test/tools/llvm-link/hello.ll b/test/tools/llvm-link/hello.ll<br>
> > > new file mode 100644<br>
> > > index 0000000..c124864<br>
> > > --- /dev/null<br>
> > > +++ b/test/tools/llvm-link/hello.ll<br>
> > > @@ -0,0 +1,20 @@<br>
> > > +; RUN: llvm-as %s -o %t-hello.bc<br>
> > > +; RUN: llvm-as %p/Inputs/foo.ll -o %t-foo.bc<br>
> ><br>
> > Why not just use llvm-link directly?<br>
> ><br>
> > I initially thought it wanted .bc only and just hadn't updated the test there.<br>
> ><br>
> ><br>
> > Also, I recommend this naming scheme:<br>
> ><br>
> > test/Linker/manual-override.ll<br>
> > test/Linker/Inputs/manual-override.ll<br>
> ><br>
> > (Or whatever you want to name the tests, but I wouldn't call it "hello".)<br>
> ><br>
> > I'd also use `%S` instead of `%p`, since last I checked only the<br>
> > former is actually documented at <a href="http://llvm.org" target="_blank">llvm.org</a>.<br>
> ><br>
> > Also, it might be worth testing both command-line orderings.<br>
> ><br>
> > Added.<br>
> ><br>
> ><br>
> > > +; RUN: llvm-link %t-hello.bc -override %t-foo.bc -S | FileCheck %s<br>
> > > +<br>
> > > +<br>
> > > +; CHECK-LABEL: define i32 @foo<br>
> > > +; CHECK-NEXT: entry:<br>
> > > +; CHECK-NEXT: ret i32 4<br>
> > > +define i32 @foo(i32 %i) {<br>
> > > +entry:<br>
> > > + %add = add nsw i32 %i, %i<br>
> > > + ret i32 %add<br>
> > > +}<br>
> > > +<br>
> > > +; Function Attrs: nounwind ssp uwtable<br>
> > > +define i32 @main(i32 %argc, i8** %argv) {<br>
> > > +entry:<br>
> > > + %a = call i32 @foo(i32 2)<br>
> > > + ret i32 %a<br>
> > > +}<br>
> > > diff --git a/test/tools/llvm-link/lit.local.cfg b/test/tools/llvm-link/lit.local.cfg<br>
> > > new file mode 100644<br>
> > > index 0000000..c6106e4<br>
> > > --- /dev/null<br>
> > > +++ b/test/tools/llvm-link/lit.local.cfg<br>
> > > @@ -0,0 +1 @@<br>
> > > +config.suffixes = ['.ll']<br>
> ><br>
> > Since the tests should probably be moved to `test/Linker`, we probably<br>
> > don't need this.<br>
> ><br>
> > > diff --git a/tools/llvm-link/llvm-link.cpp b/tools/llvm-link/llvm-link.cpp<br>
> > > index 6924aa5..54d49f5 100644<br>
> > > --- a/tools/llvm-link/llvm-link.cpp<br>
> > > +++ b/tools/llvm-link/llvm-link.cpp<br>
> > > @@ -38,6 +38,11 @@ static cl::list<std::string><br>
> > > InputFilenames(cl::Positional, cl::OneOrMore,<br>
> > > cl::desc("<input bitcode files>"));<br>
> > ><br>
> > > +static cl::list<std::string><br>
> > > +OverridingInputs("override", cl::ZeroOrMore, cl::value_desc("filename"),<br>
> > > + cl::desc("input bitcode file which can "<br>
> > > + "override previously defined symbol"));<br>
> > > +<br>
> > > static cl::opt<std::string><br>
> > > OutputFilename("o", cl::desc("Override output filename"), cl::init("-"),<br>
> > > cl::value_desc("filename"));<br>
> > > @@ -109,24 +114,29 @@ int main(int argc, char **argv) {<br>
> > > auto Composite = make_unique<Module>("llvm-link", Context);<br>
> > > Linker L(Composite.get(), diagnosticHandler);<br>
> > ><br>
> > > - for (unsigned i = 0; i < InputFilenames.size(); ++i) {<br>
> > > - std::unique_ptr<Module> M = loadFile(argv[0], InputFilenames[i], Context);<br>
> > > - if (!M.get()) {<br>
> > > - errs() << argv[0] << ": error loading file '" <<InputFilenames[i]<< "'\n";<br>
> > > - return 1;<br>
> > > - }<br>
> > > + auto linkFiles = [&](const cl::list<std::string>& Files, bool Override) {<br>
> > > + for (auto File : Files) {<br>
> > > + std::unique_ptr<Module> M = loadFile(argv[0], File, Context);<br>
> > > + if (!M.get()) {<br>
> > > + errs() << argv[0] << ": error loading file '" << File << "'\n";<br>
> > > + exit(1);<br>
> > > + }<br>
> > ><br>
> > > - if (verifyModule(*M, &errs())) {<br>
> > > - errs() << argv[0] << ": " << InputFilenames[i]<br>
> > > - << ": error: input module is broken!\n";<br>
> > > - return 1;<br>
> > > - }<br>
> > > + if (verifyModule(*M, &errs())) {<br>
> > > + errs() << argv[0] << ": " << File<br>
> > > + << ": error: input module is broken!\n";<br>
> > > + exit(1);<br>
> > > + }<br>
> > ><br>
> > > - if (Verbose) errs() << "Linking in '" << InputFilenames[i] << "'\n";<br>
> > > + if (Verbose) errs() << "Linking in '" << File << "'\n";<br>
> > ><br>
> > > - if (L.linkInModule(M.get()))<br>
> > > - return 1;<br>
> > > - }<br>
> > > + if (L.linkInModule(M.get(), Override))<br>
> > > + exit(1);<br>
> > > + }<br>
> > > + };<br>
> > > +<br>
> > > + linkFiles(InputFilenames, false);<br>
> ><br>
> > It'd be nice for the refactoring part of this (i.e., the part that<br>
> > changes all the indentation) to be in a separate NFC (no functionality<br>
> > change) commit so it's easier to see what has really changed.<br>
> ><br>
> > Done.<br>
><br>
> Ah, but the order seems wrong.<br>
><br>
> In this case, anyway, putting the NFC commit first gives you two<br>
> distinct changes: (1) refactor to make the code reusable, (2) actually<br>
> reuse the code, adding a flag and condition, etc. Each commit stands<br>
> on its own and is easy to post-commit review (first commit, refactoring<br>
> noise; second commit, small functional change).<br>
><br>
> The order you chose (NFC second) adds the duplicate/different code and<br>
> then cleans it up. The first patch -- the one with real changes -- is<br>
> *bigger* than your original patch, whereas my goal was to minimize the<br>
> noise around the functional changes. Please reverse the commits.<br>
><br>
> Swapped the order of the commits.<br>
><br>
><br>
> > + auto linkFiles = [&](const cl::list<std::string>& Files, bool Override) {<br>
><br>
> Since I've gotten all nit-picky here anyway... I wonder whether using a<br>
> lambda function is actually useful here. It saves passing `argv[0]` and<br>
> `Context`, but I'm not sure that's buying much over just creating a<br>
> normal `static` function. The latter seems just as clear, or maybe even<br>
> clearer. I don't have a strong opinion; it's up to you.<br>
><br>
> Switched to a static function since that's what the rest of the code seems to<br>
> be doing.<br>
><br>
><br>
> > Subject: [PATCH 1/2] [llvm-link] Add -override flag to prefer one of a<br>
> > duplicate symbol.<br>
><br>
> Since you've attached patches from git, I've had a look at the commit<br>
> messages, and the functional one in particular doesn't really explain<br>
> the motivation.<br>
><br>
> When you actually commit this you should describe the workflow that<br>
> you're planning to use this in, or otherwise explain why this flag is<br>
> useful.<br>
><br>
> (Do you have commit access? If not, let me know when you send the next<br>
> version of the patch and I'll commit it for you. In that case I can<br>
> just reuse my own writeup from earlier in the thread if you want.)<br>
><br>
> No, I don't have commit access so that'd be great!<br>
><br>
><br>
> > ---<br>
> > include/llvm/Linker/Linker.h | 4 +++-<br>
> > lib/Linker/LinkModules.cpp | 19 +++++++++++++++----<br>
> > test/Linker/Inputs/manual-override.ll | 4 ++++<br>
> > test/Linker/manual-override.ll | 19 +++++++++++++++++++<br>
> > tools/llvm-link/llvm-link.cpp | 26 +++++++++++++++++++++++++-<br>
><br>
> The testcases look a little light. Can you confirm what should happen<br>
> if the linkage types differ? For example, if the -override is `linkonce`<br>
> and the normal function is `weak`, IIUC the code will choose the<br>
> `linkonce` function (thusly ignoring linkage rules). This makes sense to<br>
> me -- that's what -override sounds like it should do -- but you should<br>
> test it.<br>
><br>
> Added.<br>
><br>
><br>
> Also, a test confirming that functions with `internal` linkage are<br>
> unaffected makes sense to me. I.e., if you have `internal foo` in the<br>
> main file, and normal (external) linkage in the -override file, the<br>
> `internal foo` should be renamed out of the way instead of replaced.<br>
> Similarly, an `internal foo` from the -override file should get renamed<br>
> on collisions. (It looks like this is what will happen already, and it<br>
> seems right to me, but I think it deserves a test.)<br>
><br>
> These too, but I did have to make one more small change to lib/Linker<br>
> to get the latter case working. Otherwise it would just ignore the internal<br>
> symbol from the -override input.<br>
><br>
><br>
> Finally, one whitespace bug below:<br>
><br>
> > diff --git a/tools/llvm-link/llvm-link.cpp b/tools/llvm-link/llvm-link.cpp<br>
> > index 485a7b2..54d49f5 100644<br>
> > --- a/tools/llvm-link/llvm-link.cpp<br>
> > +++ b/tools/llvm-link/llvm-link.cpp<br>
> > @@ -114,43 +114,29 @@ int main(int argc, char **argv) {<br>
> > auto Composite = make_unique<Module>("llvm-link", Context);<br>
> > Linker L(Composite.get(), diagnosticHandler);<br>
> ><br>
> > - for (unsigned i = 0; i < InputFilenames.size(); ++i) {<br>
> > - std::unique_ptr<Module> M = loadFile(argv[0], InputFilenames[i], Context);<br>
> > - if (!M.get()) {<br>
> > - errs() << argv[0] << ": error loading file '" <<InputFilenames[i]<< "'\n";<br>
> > - return 1;<br>
> > + auto linkFiles = [&](const cl::list<std::string>& Files, bool Override) {<br>
><br>
> `const cl::list<std::string>& Files` should be<br>
> `const cl::list<std::string> &Files`. I recommend adding clang-format-diff<br>
> to your workflow:<br>
><br>
> <a href="http://clang.llvm.org/docs/ClangFormat.html#script-for-patch-reformatting" target="_blank">http://clang.llvm.org/docs/ClangFormat.html#script-for-patch-reformatting</a><br>
><br>
> Ah cool, thanks!<br>
><br>
><br>
><br>
> > + for (auto File : Files) {<br>
> > + std::unique_ptr<Module> M = loadFile(argv[0], File, Context);<br>
> > + if (!M.get()) {<br>
> > + errs() << argv[0] << ": error loading file '" << File << "'\n";<br>
> > + exit(1);<br>
> > + }<br>
> ><br>
><br>
><br>
> > > + linkFiles(OverridingInputs, true);<br>
> > ><br>
> > > if (DumpAsm) errs() << "Here's the assembly:\n" << *Composite;<br>
> > ><br>
> > > --<br>
> > > 2.3.0 (Apple Git-54)<br>
> > ><br>
> > ><br>
> ><br>
> ><br>
> ><br>
> ><br>
> > <0001-llvm-link-Add-override-flag-to-prefer-one-of-a-dupli.patch><0002-llvm-link-Factor-out-code-for-handling-regular-and-o.patch><br>
><br>
><br>
><br>
</div></div>> <0002-llvm-link-Add-override-flag-to-prefer-one-of-a-dupli.patch><br>
<br>
</blockquote></div><br></div>