https://github.com/elizabethandrews updated https://github.com/llvm/llvm-project/pull/71706
>From 534fad70af45a6a22ba2d03f474089e896f4fcd6 Mon Sep 17 00:00:00 2001 From: Elizabeth Andrews <elizabeth.andr...@intel.com> Date: Thu, 26 Oct 2023 08:53:54 -0700 Subject: [PATCH 1/3] [Clang] Fix linker error for function multiversioning MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently target_clones attribute results in a linker error when there are no multi-versioned function declarations in the calling TU. In the calling TU, the call is generated with the ‘normal’ assembly name. This does not match any of the versions or the ifunc, since version mangling includes a .versionstring, and the ifunc includes .ifunc suffix. The linker error is not seen with GCC since the mangling for the ifunc symbol in GCC is the ‘normal’ assembly name for function i.e. no ifunc suffix. This PR removes the .ifunc suffix to match GCC. It also adds alias with the .ifunc suffix so as to ensure backward compatibility. The changes exclude aarch64 target because the mangling for default versions on aarch64 does not include a .default suffix and is the 'normal' assembly name, unlike other targets. It is not clear to me what the correct behavior for this target is. --- clang/docs/ReleaseNotes.rst | 1 + clang/lib/CodeGen/CodeGenModule.cpp | 35 +++++++++++++++++--- clang/test/CodeGen/attr-target-clones.c | 33 +++++++++++------- clang/test/CodeGenCXX/attr-target-clones.cpp | 27 +++++++++------ 4 files changed, 70 insertions(+), 26 deletions(-) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 8bac599f88503af..9e73fa03a0355b4 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -550,6 +550,7 @@ Bug Fixes in This Version Fixes (`#67687 <https://github.com/llvm/llvm-project/issues/67687>`_) - Fix crash from constexpr evaluator evaluating uninitialized arrays as rvalue. Fixes (`#67317 <https://github.com/llvm/llvm-project/issues/67317>`_) +- Fix linker error when using multiversioned function defined in a different TU. Bug Fixes to Compiler Builtins ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index 2e96fff808113ba..b54c4296a0f9dc6 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -4098,8 +4098,26 @@ void CodeGenModule::emitMultiVersionFunctions() { } llvm::Constant *ResolverConstant = GetOrCreateMultiVersionResolver(GD); - if (auto *IFunc = dyn_cast<llvm::GlobalIFunc>(ResolverConstant)) + if (auto *IFunc = dyn_cast<llvm::GlobalIFunc>(ResolverConstant)) { ResolverConstant = IFunc->getResolver(); + // In Aarch64, default versions of multiversioned functions are mangled to + // their 'normal' assembly name. This deviates from other targets which + // append a '.default' string. As a result we need to continue appending + // .ifunc in Aarch64. + // FIXME: Should Aarch64 mangling for 'default' multiversion function and + // in turn ifunc function match that of other targets? + if (FD->isTargetClonesMultiVersion() && + !getTarget().getTriple().isAArch64()) { + const CGFunctionInfo &FI = getTypes().arrangeGlobalDeclaration(GD); + llvm::FunctionType *DeclTy = getTypes().GetFunctionType(FI); + std::string MangledName = getMangledNameImpl( + *this, GD, FD, /*OmitMultiVersionMangling=*/true); + auto *Alias = llvm::GlobalAlias::create( + DeclTy, 0, llvm::Function::WeakODRLinkage, MangledName + ".ifunc", + IFunc, &getModule()); + SetCommonAttributes(FD, Alias); + } + } llvm::Function *ResolverFunc = cast<llvm::Function>(ResolverConstant); ResolverFunc->setLinkage(getMultiversionLinkage(*this, GD)); @@ -4266,10 +4284,19 @@ llvm::Constant *CodeGenModule::GetOrCreateMultiVersionResolver(GlobalDecl GD) { // Holds the name of the resolver, in ifunc mode this is the ifunc (which has // a separate resolver). std::string ResolverName = MangledName; - if (getTarget().supportsIFunc()) - ResolverName += ".ifunc"; - else if (FD->isTargetMultiVersion()) + if (getTarget().supportsIFunc()) { + // In Aarch64, default versions of multiversioned functions are mangled to + // their 'normal' assembly name. This deviates from other targets which + // append a '.default' string. As a result we need to continue appending + // .ifunc in Aarch64. + // FIXME: Should Aarch64 mangling for 'default' multiversion function and + // in turn ifunc function match that of other targets? + if (!FD->isTargetClonesMultiVersion() || + getTarget().getTriple().isAArch64()) + ResolverName += ".ifunc"; + } else if (FD->isTargetMultiVersion()) { ResolverName += ".resolver"; + } // If the resolver has already been created, just return it. if (llvm::GlobalValue *ResolverGV = GetGlobalValue(ResolverName)) diff --git a/clang/test/CodeGen/attr-target-clones.c b/clang/test/CodeGen/attr-target-clones.c index 98ffea40f56d887..0b7c44f26acc6b8 100644 --- a/clang/test/CodeGen/attr-target-clones.c +++ b/clang/test/CodeGen/attr-target-clones.c @@ -16,13 +16,22 @@ // LINUX: @__cpu_model = external dso_local global { i32, i32, i32, [1 x i32] } // LINUX: @__cpu_features2 = external dso_local global [3 x i32] -// LINUX: @internal.ifunc = internal ifunc i32 (), ptr @internal.resolver -// LINUX: @foo.ifunc = weak_odr ifunc i32 (), ptr @foo.resolver -// LINUX: @foo_dupes.ifunc = weak_odr ifunc void (), ptr @foo_dupes.resolver -// LINUX: @unused.ifunc = weak_odr ifunc void (), ptr @unused.resolver -// LINUX: @foo_inline.ifunc = weak_odr ifunc i32 (), ptr @foo_inline.resolver -// LINUX: @foo_inline2.ifunc = weak_odr ifunc i32 (), ptr @foo_inline2.resolver -// LINUX: @foo_used_no_defn.ifunc = weak_odr ifunc i32 (), ptr @foo_used_no_defn.resolver +// LINUX: @internal.ifunc = weak_odr alias i32 (), ptr @internal +// LINUX: @foo.ifunc = weak_odr alias i32 (), ptr @foo +// LINUX: @foo_dupes.ifunc = weak_odr alias void (), ptr @foo_dupes +// LINUX: @unused.ifunc = weak_odr alias void (), ptr @unused +// LINUX: @foo_inline.ifunc = weak_odr alias i32 (), ptr @foo_inline +// LINUX: @foo_inline2.ifunc = weak_odr alias i32 (), ptr @foo_inline2 +// LINUX: @foo_used_no_defn.ifunc = weak_odr alias i32 (), ptr @foo_used_no_defn +// LINUX: @isa_level.ifunc = weak_odr alias i32 (i32), ptr @isa_level + +// LINUX: @internal = internal ifunc i32 (), ptr @internal.resolver +// LINUX: @foo = weak_odr ifunc i32 (), ptr @foo.resolver +// LINUX: @foo_dupes = weak_odr ifunc void (), ptr @foo_dupes.resolver +// LINUX: @unused = weak_odr ifunc void (), ptr @unused.resolver +// LINUX: @foo_inline = weak_odr ifunc i32 (), ptr @foo_inline.resolver +// LINUX: @foo_inline2 = weak_odr ifunc i32 (), ptr @foo_inline2.resolver +// LINUX: @foo_used_no_defn = weak_odr ifunc i32 (), ptr @foo_used_no_defn.resolver static int __attribute__((target_clones("sse4.2, default"))) internal(void) { return 0; } int use(void) { return internal(); } @@ -60,7 +69,7 @@ void bar2(void) { // LINUX: define {{.*}}void @bar2() // WINDOWS: define dso_local void @bar2() foo_dupes(); - // LINUX: call void @foo_dupes.ifunc() + // LINUX: call void @foo_dupes() // WINDOWS: call void @foo_dupes() } @@ -68,7 +77,7 @@ int bar(void) { // LINUX: define {{.*}}i32 @bar() #[[DEF:[0-9]+]] // WINDOWS: define dso_local i32 @bar() #[[DEF:[0-9]+]] return foo(); - // LINUX: call i32 @foo.ifunc() + // LINUX: call i32 @foo() // WINDOWS: call i32 @foo() } @@ -95,8 +104,8 @@ int bar3(void) { // LINUX: define {{.*}}i32 @bar3() // WINDOWS: define dso_local i32 @bar3() return foo_inline() + foo_inline2(); - // LINUX: call i32 @foo_inline.ifunc() - // LINUX: call i32 @foo_inline2.ifunc() + // LINUX: call i32 @foo_inline() + // LINUX: call i32 @foo_inline2() // WINDOWS: call i32 @foo_inline() // WINDOWS: call i32 @foo_inline2() } @@ -134,7 +143,7 @@ int test_foo_used_no_defn(void) { // LINUX: define {{.*}}i32 @test_foo_used_no_defn() // WINDOWS: define dso_local i32 @test_foo_used_no_defn() return foo_used_no_defn(); - // LINUX: call i32 @foo_used_no_defn.ifunc() + // LINUX: call i32 @foo_used_no_defn() // WINDOWS: call i32 @foo_used_no_defn() } diff --git a/clang/test/CodeGenCXX/attr-target-clones.cpp b/clang/test/CodeGenCXX/attr-target-clones.cpp index 86293b98dbbd35f..fd2d38062a71e51 100644 --- a/clang/test/CodeGenCXX/attr-target-clones.cpp +++ b/clang/test/CodeGenCXX/attr-target-clones.cpp @@ -1,13 +1,20 @@ // RUN: %clang_cc1 -std=c++11 -triple x86_64-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefix=LINUX // RUN: %clang_cc1 -std=c++11 -triple x86_64-windows-pc -emit-llvm %s -o - | FileCheck %s --check-prefix=WINDOWS +// Aliases for ifuncs +// LINUX: @_Z10overloadedi.ifunc = weak_odr alias i32 (i32), ptr @_Z10overloadedi +// LINUX: @_Z10overloadedPKc.ifunc = weak_odr alias i32 (ptr), ptr @_Z10overloadedPKc +// LINUX: @_ZN1CIssE3fooEv.ifunc = weak_odr alias i32 (ptr), ptr @_ZN1CIssE3fooEv +// LINUX: @_ZN1CIisE3fooEv.ifunc = weak_odr alias i32 (ptr), ptr @_ZN1CIisE3fooEv +// LINUX: @_ZN1CIdfE3fooEv.ifunc = weak_odr alias i32 (ptr), ptr @_ZN1CIdfE3fooEv + // Overloaded ifuncs -// LINUX: @_Z10overloadedi.ifunc = weak_odr ifunc i32 (i32), ptr @_Z10overloadedi.resolver -// LINUX: @_Z10overloadedPKc.ifunc = weak_odr ifunc i32 (ptr), ptr @_Z10overloadedPKc.resolver +// LINUX: @_Z10overloadedi = weak_odr ifunc i32 (i32), ptr @_Z10overloadedi.resolver +// LINUX: @_Z10overloadedPKc = weak_odr ifunc i32 (ptr), ptr @_Z10overloadedPKc.resolver // struct 'C' ifuncs, note the 'float, U' one doesn't get one. -// LINUX: @_ZN1CIssE3fooEv.ifunc = weak_odr ifunc i32 (ptr), ptr @_ZN1CIssE3fooEv.resolver -// LINUX: @_ZN1CIisE3fooEv.ifunc = weak_odr ifunc i32 (ptr), ptr @_ZN1CIisE3fooEv.resolver -// LINUX: @_ZN1CIdfE3fooEv.ifunc = weak_odr ifunc i32 (ptr), ptr @_ZN1CIdfE3fooEv.resolver +// LINUX: @_ZN1CIssE3fooEv = weak_odr ifunc i32 (ptr), ptr @_ZN1CIssE3fooEv.resolver +// LINUX: @_ZN1CIisE3fooEv = weak_odr ifunc i32 (ptr), ptr @_ZN1CIisE3fooEv.resolver +// LINUX: @_ZN1CIdfE3fooEv = weak_odr ifunc i32 (ptr), ptr @_ZN1CIdfE3fooEv.resolver int __attribute__((target_clones("sse4.2", "default"))) overloaded(int) { return 1; } // LINUX: define {{.*}}i32 @_Z10overloadedi.sse4.2.0(i32{{.+}}) @@ -37,10 +44,10 @@ int __attribute__((target_clones("arch=ivybridge", "default"))) overloaded(const void use_overloaded() { overloaded(1); - // LINUX: call noundef i32 @_Z10overloadedi.ifunc + // LINUX: call noundef i32 @_Z10overloadedi // WINDOWS: call noundef i32 @"?overloaded@@YAHH@Z" overloaded(nullptr); - // LINUX: call noundef i32 @_Z10overloadedPKc.ifunc + // LINUX: call noundef i32 @_Z10overloadedPKc // WINDOWS: call noundef i32 @"?overloaded@@YAHPEBD@Z" } @@ -64,11 +71,11 @@ int __attribute__((target_clones("sse4.2", "default"))) foo(){ return 3;} void uses_specialized() { C<short, short> c; c.foo(); - // LINUX: call noundef i32 @_ZN1CIssE3fooEv.ifunc(ptr + // LINUX: call noundef i32 @_ZN1CIssE3fooEv(ptr // WINDOWS: call noundef i32 @"?foo@?$C@FF@@QEAAHXZ"(ptr C<int, short> c2; c2.foo(); - // LINUX: call noundef i32 @_ZN1CIisE3fooEv.ifunc(ptr + // LINUX: call noundef i32 @_ZN1CIisE3fooEv(ptr // WINDOWS: call noundef i32 @"?foo@?$C@HF@@QEAAHXZ"(ptr C<float, short> c3; c3.foo(); @@ -77,7 +84,7 @@ void uses_specialized() { // WINDOWS: call noundef i32 @"?foo@?$C@MF@@QEAAHXZ"(ptr C<double, float> c4; c4.foo(); - // LINUX: call noundef i32 @_ZN1CIdfE3fooEv.ifunc(ptr + // LINUX: call noundef i32 @_ZN1CIdfE3fooEv(ptr // WINDOWS: call noundef i32 @"?foo@?$C@NM@@QEAAHXZ"(ptr } >From 362f0cbb435c5a37969c2d23bda18063af75d500 Mon Sep 17 00:00:00 2001 From: Elizabeth Andrews <elizabeth.andr...@intel.com> Date: Tue, 14 Nov 2023 12:00:13 -0800 Subject: [PATCH 2/3] Use getMultiversionLinkage() for Linkage when generating alias --- clang/lib/CodeGen/CodeGenModule.cpp | 4 ++-- clang/test/CodeGen/attr-target-clones.c | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index b54c4296a0f9dc6..b6f26278a25a750 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -4113,8 +4113,8 @@ void CodeGenModule::emitMultiVersionFunctions() { std::string MangledName = getMangledNameImpl( *this, GD, FD, /*OmitMultiVersionMangling=*/true); auto *Alias = llvm::GlobalAlias::create( - DeclTy, 0, llvm::Function::WeakODRLinkage, MangledName + ".ifunc", - IFunc, &getModule()); + DeclTy, 0, getMultiversionLinkage(*this, GD), + MangledName + ".ifunc", IFunc, &getModule()); SetCommonAttributes(FD, Alias); } } diff --git a/clang/test/CodeGen/attr-target-clones.c b/clang/test/CodeGen/attr-target-clones.c index 0b7c44f26acc6b8..2bcec08d52bf911 100644 --- a/clang/test/CodeGen/attr-target-clones.c +++ b/clang/test/CodeGen/attr-target-clones.c @@ -16,7 +16,7 @@ // LINUX: @__cpu_model = external dso_local global { i32, i32, i32, [1 x i32] } // LINUX: @__cpu_features2 = external dso_local global [3 x i32] -// LINUX: @internal.ifunc = weak_odr alias i32 (), ptr @internal +// LINUX: @internal.ifunc = internal alias i32 (), ptr @internal // LINUX: @foo.ifunc = weak_odr alias i32 (), ptr @foo // LINUX: @foo_dupes.ifunc = weak_odr alias void (), ptr @foo_dupes // LINUX: @unused.ifunc = weak_odr alias void (), ptr @unused >From 763221c1637b5004f78e39916028d51fed769531 Mon Sep 17 00:00:00 2001 From: Elizabeth Andrews <elizabeth.andr...@intel.com> Date: Fri, 1 Dec 2023 08:26:31 -0800 Subject: [PATCH 3/3] Apply review comments --- clang/docs/ReleaseNotes.rst | 4 +++- clang/include/clang/Basic/AttrDocs.td | 6 ++++++ clang/lib/CodeGen/CodeGenModule.cpp | 3 +++ clang/test/CodeGen/attr-target-clones.c | 1 + 4 files changed, 13 insertions(+), 1 deletion(-) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index af90e6dcc7fa080..2dc7114a3587d6d 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -555,7 +555,9 @@ Bug Fixes in This Version Fixes (`#67687 <https://github.com/llvm/llvm-project/issues/67687>`_) - Fix crash from constexpr evaluator evaluating uninitialized arrays as rvalue. Fixes (`#67317 <https://github.com/llvm/llvm-project/issues/67317>`_) -- Fix linker error when using multiversioned function defined in a different TU. +- Fix the name of the ifunc symbol emitted for multiversion functions declared with the + ``target_clones`` attribute. This addresses a linker error that would otherwise occur + when these functions are referenced from other TUs - Fixed an issue that a benign assertion might hit when instantiating a pack expansion inside a lambda. (`#61460 <https://github.com/llvm/llvm-project/issues/61460>`_) diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td index fa6f6acd0c30e88..c54c9e690bd9012 100644 --- a/clang/include/clang/Basic/AttrDocs.td +++ b/clang/include/clang/Basic/AttrDocs.td @@ -2515,6 +2515,12 @@ example, the following will emit 4 versions of the function: __attribute__((target_clones("arch=atom,avx2","arch=ivybridge","default"))) void foo() {} +Dispatch is done via ``ifunc`` mechanism. The assembler name of the indirect +function is the original assembler name of the multiversioned function. For +backward compatibility, an alias to this function is currently generated +with an ``.ifunc`` suffix. This symbol is deprecated and will be removed +in the future. + }]; } diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index 2b43fe4fd77bfea..9e6fef33efde234 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -4128,6 +4128,9 @@ void CodeGenModule::emitMultiVersionFunctions() { llvm::FunctionType *DeclTy = getTypes().GetFunctionType(FI); std::string MangledName = getMangledNameImpl( *this, GD, FD, /*OmitMultiVersionMangling=*/true); + // In prior versions of Clang, the mangling for ifuncs incorrectly + // included an .ifunc suffix. This alias is generated for backward + // compatibility and should be deprecated in the future. auto *Alias = llvm::GlobalAlias::create( DeclTy, 0, getMultiversionLinkage(*this, GD), MangledName + ".ifunc", IFunc, &getModule()); diff --git a/clang/test/CodeGen/attr-target-clones.c b/clang/test/CodeGen/attr-target-clones.c index 2bcec08d52bf911..4b99914031b10e5 100644 --- a/clang/test/CodeGen/attr-target-clones.c +++ b/clang/test/CodeGen/attr-target-clones.c @@ -32,6 +32,7 @@ // LINUX: @foo_inline = weak_odr ifunc i32 (), ptr @foo_inline.resolver // LINUX: @foo_inline2 = weak_odr ifunc i32 (), ptr @foo_inline2.resolver // LINUX: @foo_used_no_defn = weak_odr ifunc i32 (), ptr @foo_used_no_defn.resolver +// LINUX: @isa_level = weak_odr ifunc i32 (i32), ptr @isa_level.resolver static int __attribute__((target_clones("sse4.2, default"))) internal(void) { return 0; } int use(void) { return internal(); } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
