ibookstein updated this revision to Diff 411409.
ibookstein edited the summary of this revision.
ibookstein added a comment.
Changed code to generating a function declaration and 'upgrading'
it to an ifunc instead of generating and ifunc and 'downgrading'
it to a function declaration. I decided against changing it to
bind against the unsuffixed alias instead of the ifunc, though,
because that seems to be more involved for little benefit.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D120266/new/
https://reviews.llvm.org/D120266
Files:
clang/lib/CodeGen/CodeGenModule.cpp
clang/test/CodeGen/attr-cpuspecific.c
Index: clang/test/CodeGen/attr-cpuspecific.c
===================================================================
--- clang/test/CodeGen/attr-cpuspecific.c
+++ clang/test/CodeGen/attr-cpuspecific.c
@@ -8,6 +8,7 @@
#endif // _MSC_VER
// Each version should have an IFunc and an alias.
+// LINUX: @SingleVersion = weak_odr alias void (), void ()* @SingleVersion.ifunc
// LINUX: @TwoVersions = weak_odr alias void (), void ()* @TwoVersions.ifunc
// LINUX: @TwoVersionsSameAttr = weak_odr alias void (), void ()* @TwoVersionsSameAttr.ifunc
// LINUX: @ThreeVersionsSameAttr = weak_odr alias void (), void ()* @ThreeVersionsSameAttr.ifunc
@@ -18,8 +19,8 @@
// LINUX: @GenericAndPentium = weak_odr alias i32 (i32, double), i32 (i32, double)* @GenericAndPentium.ifunc
// LINUX: @DispatchFirst = weak_odr alias i32 (), i32 ()* @DispatchFirst.ifunc
-// LINUX: @TwoVersions.ifunc = weak_odr ifunc void (), void ()* ()* @TwoVersions.resolver
// LINUX: @SingleVersion.ifunc = weak_odr ifunc void (), void ()* ()* @SingleVersion.resolver
+// LINUX: @TwoVersions.ifunc = weak_odr ifunc void (), void ()* ()* @TwoVersions.resolver
// LINUX: @TwoVersionsSameAttr.ifunc = weak_odr ifunc void (), void ()* ()* @TwoVersionsSameAttr.resolver
// LINUX: @ThreeVersionsSameAttr.ifunc = weak_odr ifunc void (), void ()* ()* @ThreeVersionsSameAttr.resolver
// LINUX: @NoSpecifics.ifunc = weak_odr ifunc void (), void ()* ()* @NoSpecifics.resolver
@@ -34,6 +35,21 @@
// LINUX: define{{.*}} void @SingleVersion.S() #[[S:[0-9]+]]
// WINDOWS: define dso_local void @SingleVersion.S() #[[S:[0-9]+]]
+ATTR(cpu_dispatch(ivybridge))
+void SingleVersion(void);
+// LINUX: define weak_odr void ()* @SingleVersion.resolver()
+// LINUX: call void @__cpu_indicator_init
+// LINUX: ret void ()* @SingleVersion.S
+// LINUX: call void @llvm.trap
+// LINUX: unreachable
+
+// WINDOWS: define weak_odr dso_local void @SingleVersion() comdat
+// WINDOWS: call void @__cpu_indicator_init()
+// WINDOWS: call void @SingleVersion.S()
+// WINDOWS-NEXT: ret void
+// WINDOWS: call void @llvm.trap
+// WINDOWS: unreachable
+
ATTR(cpu_specific(ivybridge))
void NotCalled(void){}
// LINUX: define{{.*}} void @NotCalled.S() #[[S]]
@@ -80,6 +96,10 @@
// CHECK: define {{.*}}void @ThreeVersionsSameAttr.S() #[[S]]
// CHECK: define {{.*}}void @ThreeVersionsSameAttr.Z() #[[K]]
+ATTR(cpu_specific(knl))
+int CpuSpecificNoDispatch(void) { return 1; }
+// CHECK: define {{.*}}i32 @CpuSpecificNoDispatch.Z() #[[K:[0-9]+]]
+
void usages(void) {
SingleVersion();
// LINUX: @SingleVersion.ifunc()
@@ -93,6 +113,9 @@
ThreeVersionsSameAttr();
// LINUX: @ThreeVersionsSameAttr.ifunc()
// WINDOWS: @ThreeVersionsSameAttr()
+ CpuSpecificNoDispatch();
+ // LINUX: @CpuSpecificNoDispatch.ifunc()
+ // WINDOWS: @CpuSpecificNoDispatch()
}
// has an extra config to emit!
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -3593,16 +3593,28 @@
CGF.EmitMultiVersionResolver(ResolverFunc, Options);
if (getTarget().supportsIFunc()) {
+ llvm::GlobalValue::LinkageTypes Linkage = getMultiversionLinkage(*this, GD);
+ auto *IFunc = cast<llvm::GlobalValue>(
+ GetOrCreateMultiVersionResolver(GD, DeclTy, FD));
+
+ // Fix up function declarations that were created for cpu_specific before
+ // cpu_dispatch was known
+ if (!dyn_cast<llvm::GlobalIFunc>(IFunc)) {
+ assert(cast<llvm::Function>(IFunc)->isDeclaration());
+ auto *GI = llvm::GlobalIFunc::create(DeclTy, 0, Linkage, "", ResolverFunc,
+ &getModule());
+ GI->takeName(IFunc);
+ IFunc->replaceAllUsesWith(GI);
+ IFunc->eraseFromParent();
+ IFunc = GI;
+ }
+
std::string AliasName = getMangledNameImpl(
*this, GD, FD, /*OmitMultiVersionMangling=*/true);
llvm::Constant *AliasFunc = GetGlobalValue(AliasName);
if (!AliasFunc) {
- auto *IFunc = cast<llvm::GlobalIFunc>(GetOrCreateLLVMFunction(
- AliasName, DeclTy, GD, /*ForVTable=*/false, /*DontDefer=*/true,
- /*IsThunk=*/false, llvm::AttributeList(), NotForDefinition));
- auto *GA = llvm::GlobalAlias::create(DeclTy, 0,
- getMultiversionLinkage(*this, GD),
- AliasName, IFunc, &getModule());
+ auto *GA = llvm::GlobalAlias::create(DeclTy, 0, Linkage, AliasName, IFunc,
+ &getModule());
SetCommonAttributes(GD, GA);
}
}
@@ -3650,7 +3662,9 @@
}
}
- if (getTarget().supportsIFunc()) {
+ // For cpu_specific, don't create an ifunc yet because we don't know if the
+ // cpu_dispatch will be emitted in this translation unit.
+ if (getTarget().supportsIFunc() && !FD->isCPUSpecificMultiVersion()) {
llvm::Type *ResolverType = llvm::FunctionType::get(
llvm::PointerType::get(
DeclTy, getContext().getTargetAddressSpace(FD->getType())),
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