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Part of initial Arm64EC patchset.
For the Arm64EC ABI, ARM64 functions have an alternate name. For C code, this
name is just the original name prefixed with "#". For C++ code, we stick a
"$$h" modifier in the middle of the mangling.
For functions which are not hybrid_patchable, the normal name is then an alias
for the alternate name. (For functions that are patchable, we have to do
something more complicated to tell the linker to generate a stub; I haven't
tried to implement that yet.)
This doesn't emit quite the same symbols table as MSVC for simple cases: MSVC
generates a IMAGE_WEAK_EXTERN_ANTI_DEPENDENCY alias, where this just makes
another symbol pointing at the function definition. This probably matters for
the hybmp$x table, but I don't have the complete documentation at the moment.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D125418
Files:
clang/include/clang/AST/Mangle.h
clang/lib/AST/MicrosoftMangle.cpp
clang/lib/CodeGen/CodeGenModule.cpp
clang/test/CodeGen/arm64ec.c
clang/test/CodeGenCXX/arm64ec.cpp
Index: clang/test/CodeGenCXX/arm64ec.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/arm64ec.cpp
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -no-opaque-pointers -triple aarch64-windows-msvc_arm64ec -emit-llvm -o - %s | FileCheck %s
+
+// CHECK: @"?g@@YAXUA@@UB@@@Z" = alias void ([2 x float], [4 x float]), void ([2 x float], [4 x float])* @"?g@@$$hYAXUA@@UB@@@Z"
+// CHECK: define dso_local void @"?g@@$$hYAXUA@@UB@@@Z"
+typedef struct { float x[2]; } A;
+typedef struct { float x[4]; } B;
+void g(A a, B b) { }
Index: clang/test/CodeGen/arm64ec.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/arm64ec.c
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -no-opaque-pointers -triple aarch64-windows-msvc_arm64ec -emit-llvm -o - %s | FileCheck %s
+
+// CHECK: @g = alias void ([2 x float], [4 x float]), void ([2 x float], [4 x float])* @"#g"
+// CHECK: define dso_local void @"#g"
+typedef struct { float x[2]; } A;
+typedef struct { float x[4]; } B;
+void g(A a, B b) { }
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -5117,6 +5117,23 @@
if (!GV->isDeclaration())
return;
+ if (getTriple().isWindowsArm64EC()) {
+ // For ARM64EC targets, a function definition's name is mangled differently
+ // from the normal symbol. We then emit an alias from the normal
+ // symbol to the remangled definition.
+ // FIXME: MSVC uses IMAGE_WEAK_EXTERN_ANTI_DEPENDENCY, we just emit
+ // multiple definition symbols. Why does this matter?
+ // FIXME: For hybrid_patchable functions, the alias doesn't point
+ // to the function itself; it points to a stub for the compiler.
+ // FIXME: We also need to emit an entry thunk.
+ SmallString<256> MangledName;
+ llvm::raw_svector_ostream Out(MangledName);
+ getCXXABI().getMangleContext().mangleArm64ECFnDef(GD, Out);
+ auto *Alias = llvm::GlobalAlias::create("", GV);
+ Alias->takeName(GV);
+ GV->setName(MangledName);
+ }
+
// We need to set linkage and visibility on the function before
// generating code for it because various parts of IR generation
// want to propagate this information down (e.g. to local static
Index: clang/lib/AST/MicrosoftMangle.cpp
===================================================================
--- clang/lib/AST/MicrosoftMangle.cpp
+++ clang/lib/AST/MicrosoftMangle.cpp
@@ -298,6 +298,7 @@
return AnonymousNamespaceHash;
}
+ void mangleArm64ECFnDef(GlobalDecl GD, raw_ostream &) override;
private:
void mangleInitFiniStub(const VarDecl *D, char CharCode, raw_ostream &Out);
};
@@ -360,7 +361,7 @@
void mangle(GlobalDecl GD, StringRef Prefix = "?");
void mangleName(GlobalDecl GD);
- void mangleFunctionEncoding(GlobalDecl GD, bool ShouldMangle);
+ void mangleFunctionEncoding(GlobalDecl GD, bool ShouldMangle, bool Arm64ECDef = false);
void mangleVariableEncoding(const VarDecl *VD);
void mangleMemberDataPointer(const CXXRecordDecl *RD, const ValueDecl *VD,
StringRef Prefix = "$");
@@ -384,6 +385,7 @@
bool ForceThisQuals = false,
bool MangleExceptionSpec = true);
void mangleNestedName(GlobalDecl GD);
+ void mangleArm64ECFnDef(GlobalDecl GD);
private:
bool isStructorDecl(const NamedDecl *ND) const {
@@ -573,7 +575,8 @@
}
void MicrosoftCXXNameMangler::mangleFunctionEncoding(GlobalDecl GD,
- bool ShouldMangle) {
+ bool ShouldMangle,
+ bool Arm64ECDef) {
const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
// <type-encoding> ::= <function-class> <function-type>
@@ -597,6 +600,8 @@
if (FD->isExternC() && FD->hasAttr<OverloadableAttr>())
Out << "$$J0";
+ if (Arm64ECDef)
+ Out << "$$h";
mangleFunctionClass(FD);
mangleFunctionType(FT, FD, false, false);
@@ -3944,6 +3949,29 @@
Mangler.getStream() << '@';
}
+void MicrosoftMangleContextImpl::mangleArm64ECFnDef(GlobalDecl GD,
+ raw_ostream &Out) {
+ const FunctionDecl *D = cast<FunctionDecl>(GD.getDecl());
+ PrettyStackTraceDecl CrashInfo(D, SourceLocation(),
+ getASTContext().getSourceManager(),
+ "Mangling Arm64EC function def");
+
+ if (!shouldMangleCXXName(D)) {
+ Out << '#' << D->getName();
+ return;
+ }
+
+ msvc_hashing_ostream MHO(Out);
+ MicrosoftCXXNameMangler Mangler(*this, MHO);
+ return Mangler.mangleArm64ECFnDef(GD);
+}
+
+void MicrosoftCXXNameMangler::mangleArm64ECFnDef(GlobalDecl GD) {
+ Out << '?';
+ mangleName(GD);
+ mangleFunctionEncoding(GD, /*ShouldMangle*/true, /*Arm64ECDef*/true);
+}
+
MicrosoftMangleContext *
MicrosoftMangleContext::create(ASTContext &Context, DiagnosticsEngine &Diags) {
return new MicrosoftMangleContextImpl(Context, Diags);
Index: clang/include/clang/AST/Mangle.h
===================================================================
--- clang/include/clang/AST/Mangle.h
+++ clang/include/clang/AST/Mangle.h
@@ -115,6 +115,10 @@
// FIXME: consider replacing raw_ostream & with something like SmallString &.
void mangleName(GlobalDecl GD, raw_ostream &);
+ // Mangling for function definitions in Arm64EC ABI.
+ virtual void mangleArm64ECFnDef(GlobalDecl GD, raw_ostream &) {
+ llvm_unreachable("Unexpected ABI");
+ }
virtual void mangleCXXName(GlobalDecl GD, raw_ostream &) = 0;
virtual void mangleThunk(const CXXMethodDecl *MD,
const ThunkInfo &Thunk,
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