[IR] Add TargetExtType::CanBeAlloca property

Add a property to allow marking target extension types that cannot be
used in an alloca instruction, similar to CanBeGlobal for global
variables.

Author: jayfoad

llvm/include/llvm/IR/DerivedTypes.h

@@ -769,6 +769,8 @@ class TargetExtType : public Type {
     HasZeroInit = 1U << 0,
     /// This type may be used as the value type of a global variable.
     CanBeGlobal = 1U << 1,
+    /// This type may be used as the allocated type of an alloca instruction.
+    CanBeAlloca = 1U << 2,
   };
 
   /// Returns true if the target extension type contains the given property.

llvm/lib/IR/Type.cpp

@@ -838,12 +838,14 @@ static TargetTypeInfo getTargetTypeInfo(const TargetExtType *Ty) {
     return TargetTypeInfo(PointerType::get(C, 0), TargetExtType::CanBeGlobal);
   if (Name.starts_with("spirv."))
     return TargetTypeInfo(PointerType::get(C, 0), TargetExtType::HasZeroInit,
-                          TargetExtType::CanBeGlobal);
+                          TargetExtType::CanBeGlobal,
+                          TargetExtType::CanBeAlloca);
 
   // Opaque types in the AArch64 name space.
   if (Name == "aarch64.svcount")
     return TargetTypeInfo(ScalableVectorType::get(Type::getInt1Ty(C), 16),
-                          TargetExtType::HasZeroInit);
+                          TargetExtType::HasZeroInit,
+                          TargetExtType::CanBeAlloca);
 
   return TargetTypeInfo(Type::getVoidTy(C));
 }

llvm/lib/IR/Verifier.cpp

@@ -4273,6 +4273,12 @@ void Verifier::visitAllocaInst(AllocaInst &AI) {
   SmallPtrSet<Type*, 4> Visited;
   Check(AI.getAllocatedType()->isSized(&Visited),
         "Cannot allocate unsized type", &AI);
+  // Check if it's a target extension type that disallows being used in an
+  // alloca.
+  if (auto *TTy = dyn_cast<TargetExtType>(AI.getAllocatedType())) {
+    Check(TTy->hasProperty(TargetExtType::CanBeAlloca),
+          "Alloca has illegal target extension type", &AI);
+  }
   Check(AI.getArraySize()->getType()->isIntegerTy(),
         "Alloca array size must have integer type", &AI);
   if (MaybeAlign A = AI.getAlign()) {

llvm/test/Assembler/target-type-properties.ll

@@ -1,6 +1,7 @@
 ; RUN: split-file %s %t
 ; RUN: not llvm-as < %t/zeroinit-error.ll -o /dev/null 2>&1 | FileCheck --check-prefix=CHECK-ZEROINIT %s
 ; RUN: not llvm-as < %t/global-var.ll -o /dev/null 2>&1 | FileCheck --check-prefix=CHECK-GLOBALVAR %s
+; RUN: not llvm-as < %t/alloca.ll -o /dev/null 2>&1 | FileCheck --check-prefix=CHECK-ALLOCA %s
 ; Check target extension type properties are verified in the assembler.
 
 ;--- zeroinit-error.ll
@@ -14,3 +15,10 @@ define void @foo() {
 ;--- global-var.ll
 @global = external global target("unknown_target_type")
 ; CHECK-GLOBALVAR: Global @global has illegal target extension type
+
+;--- alloca.ll
+define void @foo() {
+  %val = alloca target("spirv.Image")
+; CHECK-ALLOCA: Alloca has illegal target extension type
+  ret void
+}