[clang][AArch64][FMV] Stop emitting alias to ifunc. #96221
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Long story short the interaction of two optimizations happening in GlobalOpt results in a crash. For more details look at the issue llvm#96197. I will be fixing this in GlobalOpt but it is a conservative solution since it won't allow us to optimize resolvers which return a pointer to a function whose definition is in another TU when compiling without LTO: __attribute__((target_version("simd"))) void bar(void); __attribute__((target_version("default"))) void bar(void); int foo() { bar(); }
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@llvm/pr-subscribers-clang-codegen @llvm/pr-subscribers-clang Author: Alexandros Lamprineas (labrinea) ChangesLong story short the interaction of two optimizations happening in GlobalOpt results in a crash. For more details look at the issue #96197. I will be fixing this in GlobalOpt but it is a conservative solution since it won't allow us to optimize resolvers which return a pointer to a function whose definition is in another TU when compiling without LTO: attribute((target_version("simd"))) void bar(void); attribute((target_version("default"))) void bar(void); int foo() { bar(); } Full diff: https://github.com/llvm/llvm-project/pull/96221.diff 7 Files Affected:
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index dd4a665ebc78b..76534475e88f7 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -4259,8 +4259,8 @@ void CodeGenModule::emitMultiVersionFunctions() {
llvm::Constant *ResolverConstant = GetOrCreateMultiVersionResolver(GD);
if (auto *IFunc = dyn_cast<llvm::GlobalIFunc>(ResolverConstant)) {
ResolverConstant = IFunc->getResolver();
- if (FD->isTargetClonesMultiVersion() ||
- FD->isTargetVersionMultiVersion()) {
+ if (FD->isTargetClonesMultiVersion() &&
+ !getTarget().getTriple().isAArch64()) {
std::string MangledName = getMangledNameImpl(
*this, GD, FD, /*OmitMultiVersionMangling=*/true);
if (!GetGlobalValue(MangledName + ".ifunc")) {
diff --git a/clang/test/CodeGen/aarch64-mixed-target-attributes.c b/clang/test/CodeGen/aarch64-mixed-target-attributes.c
index 6aa747d4cb461..3c047fec6ceed 100644
--- a/clang/test/CodeGen/aarch64-mixed-target-attributes.c
+++ b/clang/test/CodeGen/aarch64-mixed-target-attributes.c
@@ -30,9 +30,6 @@ __attribute__((target_version("jscvt"))) int default_def_with_version_decls(void
//.
// CHECK: @__aarch64_cpu_features = external dso_local global { i64 }
-// CHECK: @explicit_default.ifunc = weak_odr alias i32 (), ptr @explicit_default
-// CHECK: @implicit_default.ifunc = weak_odr alias i32 (), ptr @implicit_default
-// CHECK: @default_def_with_version_decls.ifunc = weak_odr alias i32 (), ptr @default_def_with_version_decls
// CHECK: @explicit_default = weak_odr ifunc i32 (), ptr @explicit_default.resolver
// CHECK: @implicit_default = weak_odr ifunc i32 (), ptr @implicit_default.resolver
// CHECK: @default_def_with_version_decls = weak_odr ifunc i32 (), ptr @default_def_with_version_decls.resolver
diff --git a/clang/test/CodeGen/attr-target-clones-aarch64.c b/clang/test/CodeGen/attr-target-clones-aarch64.c
index ad6079a91fcd5..60f9c7f1fc24e 100644
--- a/clang/test/CodeGen/attr-target-clones-aarch64.c
+++ b/clang/test/CodeGen/attr-target-clones-aarch64.c
@@ -27,14 +27,6 @@ inline int __attribute__((target_clones("fp16", "sve2-bitperm+fcma", "default"))
//.
// CHECK: @__aarch64_cpu_features = external dso_local global { i64 }
-// CHECK: @ftc.ifunc = weak_odr alias i32 (), ptr @ftc
-// CHECK: @ftc_def.ifunc = weak_odr alias i32 (), ptr @ftc_def
-// CHECK: @ftc_dup1.ifunc = weak_odr alias i32 (), ptr @ftc_dup1
-// CHECK: @ftc_dup2.ifunc = weak_odr alias i32 (), ptr @ftc_dup2
-// CHECK: @ftc_dup3.ifunc = weak_odr alias i32 (), ptr @ftc_dup3
-// CHECK: @ftc_inline2.ifunc = weak_odr alias i32 (), ptr @ftc_inline2
-// CHECK: @ftc_inline1.ifunc = weak_odr alias i32 (), ptr @ftc_inline1
-// CHECK: @ftc_inline3.ifunc = weak_odr alias i32 (), ptr @ftc_inline3
// CHECK: @ftc = weak_odr ifunc i32 (), ptr @ftc.resolver
// CHECK: @ftc_def = weak_odr ifunc i32 (), ptr @ftc_def.resolver
// CHECK: @ftc_dup1 = weak_odr ifunc i32 (), ptr @ftc_dup1.resolver
@@ -45,14 +37,6 @@ inline int __attribute__((target_clones("fp16", "sve2-bitperm+fcma", "default"))
// CHECK: @ftc_inline3 = weak_odr ifunc i32 (), ptr @ftc_inline3.resolver
//.
// CHECK-MTE-BTI: @__aarch64_cpu_features = external dso_local global { i64 }
-// CHECK-MTE-BTI: @ftc.ifunc = weak_odr alias i32 (), ptr @ftc
-// CHECK-MTE-BTI: @ftc_def.ifunc = weak_odr alias i32 (), ptr @ftc_def
-// CHECK-MTE-BTI: @ftc_dup1.ifunc = weak_odr alias i32 (), ptr @ftc_dup1
-// CHECK-MTE-BTI: @ftc_dup2.ifunc = weak_odr alias i32 (), ptr @ftc_dup2
-// CHECK-MTE-BTI: @ftc_dup3.ifunc = weak_odr alias i32 (), ptr @ftc_dup3
-// CHECK-MTE-BTI: @ftc_inline2.ifunc = weak_odr alias i32 (), ptr @ftc_inline2
-// CHECK-MTE-BTI: @ftc_inline1.ifunc = weak_odr alias i32 (), ptr @ftc_inline1
-// CHECK-MTE-BTI: @ftc_inline3.ifunc = weak_odr alias i32 (), ptr @ftc_inline3
// CHECK-MTE-BTI: @ftc = weak_odr ifunc i32 (), ptr @ftc.resolver
// CHECK-MTE-BTI: @ftc_def = weak_odr ifunc i32 (), ptr @ftc_def.resolver
// CHECK-MTE-BTI: @ftc_dup1 = weak_odr ifunc i32 (), ptr @ftc_dup1.resolver
diff --git a/clang/test/CodeGen/attr-target-version.c b/clang/test/CodeGen/attr-target-version.c
index 75f8734e5aaf3..024aafffca629 100644
--- a/clang/test/CodeGen/attr-target-version.c
+++ b/clang/test/CodeGen/attr-target-version.c
@@ -137,19 +137,6 @@ int caller(void) { return used_def_without_default_decl() + used_decl_without_de
//.
// CHECK: @__aarch64_cpu_features = external dso_local global { i64 }
-// CHECK: @fmv.ifunc = weak_odr alias i32 (), ptr @fmv
-// CHECK: @fmv_one.ifunc = weak_odr alias i32 (), ptr @fmv_one
-// CHECK: @fmv_two.ifunc = weak_odr alias i32 (), ptr @fmv_two
-// CHECK: @fmv_e.ifunc = weak_odr alias i32 (), ptr @fmv_e
-// CHECK: @fmv_d.ifunc = internal alias i32 (), ptr @fmv_d
-// CHECK: @fmv_c.ifunc = weak_odr alias void (), ptr @fmv_c
-// CHECK: @fmv_inline.ifunc = weak_odr alias i32 (), ptr @fmv_inline
-// CHECK: @unused_with_default_def.ifunc = weak_odr alias i32 (), ptr @unused_with_default_def
-// CHECK: @unused_with_implicit_default_def.ifunc = weak_odr alias i32 (), ptr @unused_with_implicit_default_def
-// CHECK: @unused_with_implicit_forward_default_def.ifunc = weak_odr alias i32 (), ptr @unused_with_implicit_forward_default_def
-// CHECK: @default_def_with_version_decls.ifunc = weak_odr alias i32 (), ptr @default_def_with_version_decls
-// CHECK: @used_def_without_default_decl.ifunc = weak_odr alias i32 (), ptr @used_def_without_default_decl
-// CHECK: @used_decl_without_default_decl.ifunc = weak_odr alias i32 (), ptr @used_decl_without_default_decl
// CHECK: @fmv = weak_odr ifunc i32 (), ptr @fmv.resolver
// CHECK: @fmv_one = weak_odr ifunc i32 (), ptr @fmv_one.resolver
// CHECK: @fmv_two = weak_odr ifunc i32 (), ptr @fmv_two.resolver
diff --git a/clang/test/CodeGenCXX/attr-target-clones-aarch64.cpp b/clang/test/CodeGenCXX/attr-target-clones-aarch64.cpp
index 7953f902bf09b..29ae6b6856500 100644
--- a/clang/test/CodeGenCXX/attr-target-clones-aarch64.cpp
+++ b/clang/test/CodeGenCXX/attr-target-clones-aarch64.cpp
@@ -40,10 +40,6 @@ void run_foo_tml() {
//.
// CHECK: @__aarch64_cpu_features = external dso_local global { i64 }
-// CHECK: @_Z7foo_ovli.ifunc = weak_odr alias i32 (i32), ptr @_Z7foo_ovli
-// CHECK: @_Z7foo_ovlv.ifunc = weak_odr alias i32 (), ptr @_Z7foo_ovlv
-// CHECK: @_ZN7MyClassIssE7foo_tmlEv.ifunc = weak_odr alias i32 (ptr), ptr @_ZN7MyClassIssE7foo_tmlEv
-// CHECK: @_ZN7MyClassIisE7foo_tmlEv.ifunc = weak_odr alias i32 (ptr), ptr @_ZN7MyClassIisE7foo_tmlEv
// CHECK: @_Z7foo_ovli = weak_odr ifunc i32 (i32), ptr @_Z7foo_ovli.resolver
// CHECK: @_Z7foo_ovlv = weak_odr ifunc i32 (), ptr @_Z7foo_ovlv.resolver
// CHECK: @_ZN7MyClassIssE7foo_tmlEv = weak_odr ifunc i32 (ptr), ptr @_ZN7MyClassIssE7foo_tmlEv.resolver
diff --git a/clang/test/CodeGenCXX/attr-target-version.cpp b/clang/test/CodeGenCXX/attr-target-version.cpp
index 8b7273fe3bb51..fd19f4c5a3030 100644
--- a/clang/test/CodeGenCXX/attr-target-version.cpp
+++ b/clang/test/CodeGenCXX/attr-target-version.cpp
@@ -62,12 +62,6 @@ int bar() {
//.
// CHECK: @__aarch64_cpu_features = external dso_local global { i64 }
-// CHECK: @_Z3fooi.ifunc = weak_odr alias i32 (i32), ptr @_Z3fooi
-// CHECK: @_Z3foov.ifunc = weak_odr alias i32 (), ptr @_Z3foov
-// CHECK: @_ZN7MyClass3gooEi.ifunc = weak_odr alias i32 (ptr, i32), ptr @_ZN7MyClass3gooEi
-// CHECK: @_ZN7MyClass23unused_with_default_defEv.ifunc = weak_odr alias i32 (ptr), ptr @_ZN7MyClass23unused_with_default_defEv
-// CHECK: @_ZN7MyClass32unused_with_implicit_default_defEv.ifunc = weak_odr alias i32 (ptr), ptr @_ZN7MyClass32unused_with_implicit_default_defEv
-// CHECK: @_ZN7MyClass40unused_with_implicit_forward_default_defEv.ifunc = weak_odr alias i32 (ptr), ptr @_ZN7MyClass40unused_with_implicit_forward_default_defEv
// CHECK: @_ZN7MyClass3gooEi = weak_odr ifunc i32 (ptr, i32), ptr @_ZN7MyClass3gooEi.resolver
// CHECK: @_Z3fooi = weak_odr ifunc i32 (i32), ptr @_Z3fooi.resolver
// CHECK: @_Z3foov = weak_odr ifunc i32 (), ptr @_Z3foov.resolver
diff --git a/clang/test/CodeGenCXX/fmv-namespace.cpp b/clang/test/CodeGenCXX/fmv-namespace.cpp
index 5bcd0da06eebc..193f01db4c5d3 100644
--- a/clang/test/CodeGenCXX/fmv-namespace.cpp
+++ b/clang/test/CodeGenCXX/fmv-namespace.cpp
@@ -19,8 +19,6 @@ int baz() { return OtherName::foo(); }
//.
// CHECK: @__aarch64_cpu_features = external dso_local global { i64 }
-// CHECK: @_ZN4Name3fooEv.ifunc = weak_odr alias i32 (), ptr @_ZN4Name3fooEv
-// CHECK: @_ZN9OtherName3fooEv.ifunc = weak_odr alias i32 (), ptr @_ZN9OtherName3fooEv
// CHECK: @_ZN4Name3fooEv = weak_odr ifunc i32 (), ptr @_ZN4Name3fooEv.resolver
// CHECK: @_ZN9OtherName3fooEv = weak_odr ifunc i32 (), ptr @_ZN9OtherName3fooEv.resolver
//.
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cc @tahonermann |
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I think this needs a release note. |
DanielKristofKiss
approved these changes
Jun 20, 2024
We removed the global alias that was pointing to AArch64 Function Multiversioning ifuncs because it interacts badly with GlobalOpt.
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Long story short the interaction of two optimizations happening in GlobalOpt results in a crash. For more details look at the issue #96197. I will be fixing this in GlobalOpt but it is a conservative solution since it won't allow us to optimize resolvers which return a pointer to a function whose definition is in another TU when compiling without LTO:
fixes: #96197