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[CodeGen][ObjC] Fix assert on calling `__builtin_constant_p` with ObjC objects. 

When we are calling `__builtin_constant_p` with ObjC objects of
different classes, we hit the assertion

> Assertion failed: (isa<X>(Val) && "cast<Ty>() argument of incompatible type!"), function cast, file include/llvm/Support/Casting.h, line 254.

It happens because LLVM types for `ObjCInterfaceType` are opaque and
have no name (see `CodeGenTypes::ConvertType`). As the result, for
different ObjC classes we have different `is_constant` intrinsics with
the same name `llvm.is.constant.p0s_s`. When we try to reuse an
intrinsic with the same name, we fail because of type mismatch.

Fix by bitcasting `ObjCObjectPointerType` to `id` prior to passing as an
argument to `__builtin_constant_p`. This results in using intrinsic
`llvm.is.constant.p0i8` and correct types.

rdar://problem/47499250

Reviewers: rjmccall, ahatanak, void

Reviewed By: void, ahatanak

Subscribers: ddunbar, jkorous, hans, dexonsmith, cfe-commits

Differential Revision: https://reviews.llvm.org/D57427

llvm-svn: 353577
This commit is contained in:
Volodymyr Sapsai 2019-02-08 23:02:13 +00:00
parent 114cfafe05
commit 1570571ded
2 changed files with 34 additions and 0 deletions
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6
clang/lib/CodeGen/CGBuiltin.cpp
View File

@ -1982,6 +1982,12 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
return RValue::get(ConstantInt::get(ResultType, 0));
Value *ArgValue = EmitScalarExpr(Arg);
if (ArgType->isObjCObjectPointerType()) {
// Convert Objective-C objects to id because we cannot distinguish between
// LLVM types for Obj-C classes as they are opaque.
ArgType = CGM.getContext().getObjCIdType();
ArgValue = Builder.CreateBitCast(ArgValue, ConvertType(ArgType));
}
Function *F =
CGM.getIntrinsic(Intrinsic::is_constant, ConvertType(ArgType));
Value *Result = Builder.CreateCall(F, ArgValue);

28
clang/test/CodeGenObjC/builtin-constant-p.m Normal file
View File

@ -0,0 +1,28 @@
// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -O3 -disable-llvm-passes -o - %s | FileCheck %s
// Test that can call `__builtin_constant_p` with instances of different
// Objective-C classes.
// rdar://problem/47499250
@class Foo;
@class Bar;
extern void callee(void);
// CHECK-LABEL: define void @test(%0* %foo, %1* %bar)
void test(Foo *foo, Bar *bar) {
// CHECK: [[ADDR_FOO:%.*]] = bitcast %0* %{{.*}} to i8*
// CHECK-NEXT: call i1 @llvm.is.constant.p0i8(i8* [[ADDR_FOO]])
// CHECK: [[ADDR_BAR:%.*]] = bitcast %1* %{{.*}} to i8*
// CHECK-NEXT: call i1 @llvm.is.constant.p0i8(i8* [[ADDR_BAR]])
if (__builtin_constant_p(foo) && __builtin_constant_p(bar))
callee();
}
// Test other Objective-C types.
// CHECK-LABEL: define void @test_more(i8* %object, i8* %klass)
void test_more(id object, Class klass) {
// CHECK: call i1 @llvm.is.constant.p0i8(i8* %{{.*}})
// CHECK: call i1 @llvm.is.constant.p0i8(i8* %{{.*}})
if (__builtin_constant_p(object) && __builtin_constant_p(klass))
callee();
}