CodeGen: Allow annotations on globals in non-zero address space

Summary:
Attribute annotations are recorded in a special global composite variable
that points to annotation strings and the annotated objects.

As a restriction of the LLVM IR type system, those pointers are all
pointers to address space 0, so let's insert an addrspacecast when the
annotated global is in a non-0 address space.

Since this addrspacecast is only reachable from the global annotations
object, this should allow us to represent annotations on all globals
regardless of which addrspacecasts are usually legal for the target.

Reviewers: rjmccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D71208

Author: nhaehnle

clang/lib/CodeGen/CodeGenModule.cpp

@@ -2212,9 +2212,15 @@ llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
                  *UnitGV = EmitAnnotationUnit(L),
                  *LineNoCst = EmitAnnotationLineNo(L);
 
+  llvm::Constant *ASZeroGV = GV;
+  if (GV->getAddressSpace() != 0) {
+    ASZeroGV = llvm::ConstantExpr::getAddrSpaceCast(
+                   GV, GV->getValueType()->getPointerTo(0));
+  }
+
   // Create the ConstantStruct for the global annotation.
   llvm::Constant *Fields[4] = {
-    llvm::ConstantExpr::getBitCast(GV, Int8PtrTy),
+    llvm::ConstantExpr::getBitCast(ASZeroGV, Int8PtrTy),
     llvm::ConstantExpr::getBitCast(AnnoGV, Int8PtrTy),
     llvm::ConstantExpr::getBitCast(UnitGV, Int8PtrTy),
     LineNoCst

clang/test/CodeGen/annotations-global.c

@@ -3,6 +3,7 @@
 // RUN: FileCheck --check-prefix=A %s < %t1
 // RUN: FileCheck --check-prefix=BAR %s < %t1
 // RUN: FileCheck --check-prefix=FOOS %s < %t1
+// RUN: FileCheck --check-prefix=ADDRSPACE %s < %t1
 // END.
 
 static __attribute((annotate("sfoo_0"))) __attribute((annotate("sfoo_1"))) char sfoo;
@@ -14,28 +15,33 @@ void __attribute((annotate("ann_a_0"))) __attribute((annotate("ann_a_1"))) a(cha
   sfoo = 0;
 }
 
+__attribute((address_space(1))) __attribute__((annotate("addrspace1_ann"))) char addrspace1_var;
+
 // FOOS: target triple
 // FOOS: private unnamed_addr constant [7 x i8] c"sfoo_{{.}}\00", section "llvm.metadata"
 // FOOS: private unnamed_addr constant [7 x i8] c"sfoo_{{.}}\00", section "llvm.metadata"
 // FOOS-NOT: sfoo_
-// FOOS: @llvm.global.annotations = appending global [10 x { i8*, i8*, i8*, i32 }] {{.*}}i8* @sfoo{{.*}}i8* @sfoo{{.*}}, section "llvm.metadata"
+// FOOS: @llvm.global.annotations = appending global [11 x { i8*, i8*, i8*, i32 }] {{.*}}i8* @sfoo{{.*}}i8* @sfoo{{.*}}, section "llvm.metadata"
 
 // FOO: target triple
 // FOO: private unnamed_addr constant [6 x i8] c"foo_{{.}}\00", section "llvm.metadata"
 // FOO: private unnamed_addr constant [6 x i8] c"foo_{{.}}\00", section "llvm.metadata"
 // FOO-NOT: foo_
-// FOO: @llvm.global.annotations = appending global [10 x { i8*, i8*, i8*, i32 }] {{.*}}i8* @foo{{.*}}i8* @foo{{.*}}, section "llvm.metadata"
+// FOO: @llvm.global.annotations = appending global [11 x { i8*, i8*, i8*, i32 }] {{.*}}i8* @foo{{.*}}i8* @foo{{.*}}, section "llvm.metadata"
 
 // A: target triple
 // A: private unnamed_addr constant [8 x i8] c"ann_a_{{.}}\00", section "llvm.metadata"
 // A: private unnamed_addr constant [8 x i8] c"ann_a_{{.}}\00", section "llvm.metadata"
 // A: private unnamed_addr constant [8 x i8] c"ann_a_{{.}}\00", section "llvm.metadata"
 // A: private unnamed_addr constant [8 x i8] c"ann_a_{{.}}\00", section "llvm.metadata"
 // A-NOT: ann_a_
-// A: @llvm.global.annotations = appending global [10 x { i8*, i8*, i8*, i32 }] {{.*}}i8* bitcast (void (i8*)* @a to i8*){{.*}}i8* bitcast (void (i8*)* @a to i8*){{.*}}i8* bitcast (void (i8*)* @a to i8*){{.*}}i8* bitcast (void (i8*)* @a to i8*){{.*}}, section "llvm.metadata"
+// A: @llvm.global.annotations = appending global [11 x { i8*, i8*, i8*, i32 }] {{.*}}i8* bitcast (void (i8*)* @a to i8*){{.*}}i8* bitcast (void (i8*)* @a to i8*){{.*}}i8* bitcast (void (i8*)* @a to i8*){{.*}}i8* bitcast (void (i8*)* @a to i8*){{.*}}, section "llvm.metadata"
 
 // BAR: target triple
 // BAR: private unnamed_addr constant [6 x i8] c"bar_{{.}}\00", section "llvm.metadata"
 // BAR: private unnamed_addr constant [6 x i8] c"bar_{{.}}\00", section "llvm.metadata"
 // BAR-NOT: bar_
-// BAR: @llvm.global.annotations = appending global [10 x { i8*, i8*, i8*, i32 }] {{.*}}i8* @a.bar{{.*}}i8* @a.bar{{.*}}, section "llvm.metadata"
+// BAR: @llvm.global.annotations = appending global [11 x { i8*, i8*, i8*, i32 }] {{.*}}i8* @a.bar{{.*}}i8* @a.bar{{.*}}, section "llvm.metadata"
+
+// ADDRSPACE: target triple
+// ADDRSPACE: @llvm.global.annotations = appending global {{.*}} addrspacecast (i8 addrspace(1)* @addrspace1_var to i8*), {{.*}}