[clang] [CodeGen] Create IFUNCs in the program address space, not hard-coded 0 (PR #105726)

[Jessica Clarke via cfe-commits]

https://github.com/jrtc27 updated https://github.com/llvm/llvm-project/pull/105726

>From cfce8b0d99a088a6a2fb12661a7158786f630802 Mon Sep 17 00:00:00 2001
From: Jessica Clarke <jrtc27 at jrtc27.com>
Date: Thu, 22 Aug 2024 21:20:23 +0100
Subject: [PATCH] [CodeGen] Create IFUNCs in the program address space, not
 hard-coded 0

Commit 0d527e56a5ee ("GlobalIFunc: Make ifunc respect function address
spaces") added support for this within LLVM, but Clang does not properly
honour the target's address spaces when creating IFUNCs, crashing with
RAUW and verifier assertion failures when compiling C code on a target
with a non-zero program address space, so fix this.
---
 clang/lib/CodeGen/CodeGenModule.cpp | 24 ++++++++++++------------
 clang/test/CodeGen/ifunc.c          |  5 +++++
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 6d11bd17d0a5f5..3fbadda5bdbeda 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -4443,12 +4443,13 @@ void CodeGenModule::emitCPUDispatchDefinition(GlobalDecl GD) {
   if (getTarget().supportsIFunc()) {
     llvm::GlobalValue::LinkageTypes Linkage = getMultiversionLinkage(*this, GD);
     auto *IFunc = cast<llvm::GlobalValue>(GetOrCreateMultiVersionResolver(GD));
+    unsigned AS = IFunc->getType()->getPointerAddressSpace();
 
     // Fix up function declarations that were created for cpu_specific before
     // cpu_dispatch was known
     if (!isa<llvm::GlobalIFunc>(IFunc)) {
-      auto *GI = llvm::GlobalIFunc::create(DeclTy, 0, Linkage, "", ResolverFunc,
-                                           &getModule());
+      auto *GI = llvm::GlobalIFunc::create(DeclTy, AS, Linkage, "",
+                                           ResolverFunc, &getModule());
       replaceDeclarationWith(IFunc, GI);
       IFunc = GI;
     }
@@ -4457,8 +4458,8 @@ void CodeGenModule::emitCPUDispatchDefinition(GlobalDecl GD) {
         *this, GD, FD, /*OmitMultiVersionMangling=*/true);
     llvm::Constant *AliasFunc = GetGlobalValue(AliasName);
     if (!AliasFunc) {
-      auto *GA = llvm::GlobalAlias::create(DeclTy, 0, Linkage, AliasName, IFunc,
-                                           &getModule());
+      auto *GA = llvm::GlobalAlias::create(DeclTy, AS, Linkage, AliasName,
+                                           IFunc, &getModule());
       SetCommonAttributes(GD, GA);
     }
   }
@@ -4530,15 +4531,14 @@ llvm::Constant *CodeGenModule::GetOrCreateMultiVersionResolver(GlobalDecl GD) {
   // 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,
-                               getTypes().getTargetAddressSpace(FD->getType())),
-        false);
+    unsigned AS = getTypes().getTargetAddressSpace(FD->getType());
+    llvm::Type *ResolverType =
+        llvm::FunctionType::get(llvm::PointerType::get(DeclTy, AS), false);
     llvm::Constant *Resolver = GetOrCreateLLVMFunction(
         MangledName + ".resolver", ResolverType, GlobalDecl{},
         /*ForVTable=*/false);
     llvm::GlobalIFunc *GIF =
-        llvm::GlobalIFunc::create(DeclTy, 0, getMultiversionLinkage(*this, GD),
+        llvm::GlobalIFunc::create(DeclTy, AS, getMultiversionLinkage(*this, GD),
                                   "", Resolver, &getModule());
     GIF->setName(ResolverName);
     SetCommonAttributes(FD, GIF);
@@ -6144,9 +6144,9 @@ void CodeGenModule::emitIFuncDefinition(GlobalDecl GD) {
       GetOrCreateLLVMFunction(IFA->getResolver(), VoidTy, {},
                               /*ForVTable=*/false);
   llvm::Type *DeclTy = getTypes().ConvertTypeForMem(D->getType());
-  llvm::GlobalIFunc *GIF =
-      llvm::GlobalIFunc::create(DeclTy, 0, llvm::Function::ExternalLinkage,
-                                "", Resolver, &getModule());
+  unsigned AS = getTypes().getTargetAddressSpace(D->getType());
+  llvm::GlobalIFunc *GIF = llvm::GlobalIFunc::create(
+      DeclTy, AS, llvm::Function::ExternalLinkage, "", Resolver, &getModule());
   if (Entry) {
     if (GIF->getResolver() == Entry) {
       Diags.Report(IFA->getLocation(), diag::err_cyclic_alias) << 1;
diff --git a/clang/test/CodeGen/ifunc.c b/clang/test/CodeGen/ifunc.c
index 58a00ada687cb0..2849246f93dc3b 100644
--- a/clang/test/CodeGen/ifunc.c
+++ b/clang/test/CodeGen/ifunc.c
@@ -11,6 +11,7 @@
 // RUN: %clang_cc1 -triple x86_64-apple-macosx -fsanitize=thread -O2 -emit-llvm -o - %s | FileCheck %s --check-prefix=SAN
 // RUN: %clang_cc1 -triple arm64-apple-macosx -fsanitize=address -O2 -emit-llvm -o - %s | FileCheck %s --check-prefix=SAN
 // RUN: %clang_cc1 -triple x86_64-apple-macosx -fsanitize=address -O2 -emit-llvm -o - %s | FileCheck %s --check-prefix=SAN
+// RUN: %clang_cc1 -triple avr-unknown-unknown -emit-llvm -o - %s | FileCheck %s --check-prefix=AVR
 
 /// The ifunc is emitted before its resolver.
 int foo(int) __attribute__ ((ifunc("foo_ifunc")));
@@ -55,6 +56,10 @@ extern void hoo(int) __attribute__ ((ifunc("hoo_ifunc")));
 // CHECK: @goo = ifunc void (), ptr @goo_ifunc
 // CHECK: @hoo = ifunc void (i32), ptr @hoo_ifunc
 
+// AVR: @foo = ifunc i16 (i16), ptr addrspace(1) @foo_ifunc
+// AVR: @goo = ifunc void (), ptr addrspace(1) @goo_ifunc
+// AVR: @hoo = ifunc void (i16), ptr addrspace(1) @hoo_ifunc
+
 // CHECK: call i32 @foo(i32
 // CHECK: call void @goo()