[IRVerifier] Allow StructRet in statepoint

[cherry]

Summary

StructRet attribute is not allowed in vararg calls. The statepoint
intrinsic is vararg, but the wrapped function may be not. Allow
calls of statepoint with StructRet arg, as long as the wrapped
function is not vararg.

[anna]

This looks good to me.

lib/IR/Verifier.cpp

2825

why do you need this first condition?

[cherry]

Thank you for the review!

lib/IR/Verifier.cpp

2825

This is to handle indirect calls (and avoid crash).

lib/IR/Verifier.cpp

void Verifier::verifyStatepoint(ImmutableCallSite CS) {
   Assert(isa<ConstantInt>(FlagsV),
          "gc.statepoint flags must be constant integer", &CI);
   const uint64_t Flags = cast<ConstantInt>(FlagsV)->getZExtValue();
   Assert((Flags & ~(uint64_t)StatepointFlags::MaskAll) == 0,
          "unknown flag used in gc.statepoint flags argument", &CI);
 
   // Verify that the types of the call parameter arguments match
   // the type of the wrapped callee.
+  AttributeList Attrs = CS.getAttributes();
   for (int i = 0; i < NumParams; i++) {
     Type *ParamType = TargetFuncType->getParamType(i);
     Type *ArgType = CS.getArgument(5 + i)->getType();
     Assert(ArgType == ParamType,
            "gc.statepoint call argument does not match wrapped "
            "function type",
            &CI);
+
+    if (TargetFuncType->isVarArg()) {
+      AttributeSet ArgAttrs = Attrs.getParamAttributes(5 + i);
+      Assert(!ArgAttrs.hasAttribute(Attribute::StructRet),
+             "Attribute 'sret' cannot be used for vararg call arguments!", &CI);
+    }
   }
 
   const int EndCallArgsInx = 4 + NumCallArgs;
 
   const Value *NumTransitionArgsV = CS.getArgument(EndCallArgsInx+1);
   Assert(isa<ConstantInt>(NumTransitionArgsV),
          "gc.statepoint number of transition arguments "
          "must be constant integer",
for (unsigned Idx = FTy->getNumParams(); Idx < CS.arg_size(); ++Idx) {
                I);
         Assert(Ty->canLosslesslyBitCastTo(FTy->getReturnType()),
                "Incompatible argument and return types for 'returned' "
                "attribute",
                I);
         SawReturned = true;
       }
 
+      // Statepoint intrinsic is vararg but the wrapped function may be not.
+      // Allow sret here and check the wrapped function in verifyStatepoint.
+      if (CS.getCalledFunction() == nullptr ||
+          CS.getCalledFunction()->getIntrinsicID() !=
+            Intrinsic::experimental_gc_statepoint)
         Assert(!ArgAttrs.hasAttribute(Attribute::StructRet),
                "Attribute 'sret' cannot be used for vararg call arguments!", I);
 
       if (ArgAttrs.hasAttribute(Attribute::InAlloca))
         Assert(Idx == CS.arg_size() - 1, "inalloca isn't on the last argument!",
                I);
     }
   }
 
   // Verify that there's no metadata unless it's a direct call to an intrinsic.

test/Verifier/statepoint.ll

 ; RUN: opt -S %s -verify | FileCheck %s
 
 declare void @use(...)
 declare i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token, i32, i32)
 declare i64 addrspace(1)* @llvm.experimental.gc.relocate.p1i64(token, i32, i32)
 declare token @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
+declare token @llvm.experimental.gc.statepoint.p0f_isVoidp0s_structsf(i64, i32, void (%struct*)*, i32, i32, ...)
 declare i32 @"personality_function"()
 
 ;; Basic usage
 define i64 addrspace(1)* @test1(i8 addrspace(1)* %arg) gc "statepoint-example" {
 entry:
   %cast = bitcast i8 addrspace(1)* %arg to i64 addrspace(1)*
   %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 0, i32 0, i32 10, i32 0, i8 addrspace(1)* %arg, i64 addrspace(1)* %cast, i8 addrspace(1)* %arg, i8 addrspace(1)* %arg)
   %reloc = call i64 addrspace(1)* @llvm.experimental.gc.relocate.p1i64(token %safepoint_token, i32 12, i32 13)
exceptional_return:
   ; CHECK: gc.relocate
   ; CHECK: gc.relocate
   %landing_pad = landingpad token
           cleanup
   %obj.relocated1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token %landing_pad, i32 12, i32 12)
   %obj1.relocated1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token %landing_pad, i32 12, i32 12)
   ret i8 addrspace(1)* %obj1.relocated1
 }
+
+; Test for statepoint with sret attribute.
+; This should be allowed as long as the wrapped function is not vararg.
+%struct = type { i64, i64, i64 }
+
+declare void @fn_sret(%struct* sret)
+
+define void @test_sret() gc "statepoint-example" {
+  %x = alloca %struct
+  %statepoint_token = call token (i64, i32, void (%struct*)*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidp0s_structsf(i64 0, i32 0, void (%struct*)* @fn_sret, i32 1, i32 0, %struct* sret %x, i32 0, i32 0)
+  ret void
+  ; CHECK-LABEL: test_sret
+  ; CHECK: alloca
+  ; CHECK: statepoint
+  ; CHECK-SAME: sret
+  ; CHECK: ret
+}