; RUN: opt < %s -passes=globaldce -S | FileCheck %s target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" ; struct A { ; A(); ; virtual int foo(int); ; virtual int bar(float); ; }; ; ; struct B : A { ; B(); ; virtual int foo(int); ; virtual int bar(float); ; }; ; ; A::A() {} ; B::B() {} ; int A::foo(int) { return 1; } ; int A::bar(float) { return 2; } ; int B::foo(int) { return 3; } ; int B::bar(float) { return 4; } ; ; extern "C" int test(A *p, int (A::*q)(int)) { return (p->*q)(42); } ; Member function pointers are tracked by the combination of their object type ; and function type, which must both be compatible. Here, the call is through a ; pointer of type "int (A::*q)(int)", so the call could be dispatched to A::foo ; or B::foo. It can't be dispatched to A::bar or B::bar as the function pointer ; does not match, so those can be removed. %struct.A = type { ptr } %struct.B = type { %struct.A } ; CHECK: @_ZTV1A = internal unnamed_addr constant { [4 x ptr] } { [4 x ptr] [ptr null, ptr null, ptr @_ZN1A3fooEi, ptr null] } @_ZTV1A = internal unnamed_addr constant { [4 x ptr] } { [4 x ptr] [ptr null, ptr null, ptr @_ZN1A3fooEi, ptr @_ZN1A3barEf] }, align 8, !type !0, !type !1, !type !2, !vcall_visibility !3 ; CHECK: @_ZTV1B = internal unnamed_addr constant { [4 x ptr] } { [4 x ptr] [ptr null, ptr null, ptr @_ZN1B3fooEi, ptr null] } @_ZTV1B = internal unnamed_addr constant { [4 x ptr] } { [4 x ptr] [ptr null, ptr null, ptr @_ZN1B3fooEi, ptr @_ZN1B3barEf] }, align 8, !type !0, !type !1, !type !2, !type !4, !type !5, !type !6, !vcall_visibility !3 ; CHECK: define internal i32 @_ZN1A3fooEi( define internal i32 @_ZN1A3fooEi(ptr nocapture readnone %this, i32) unnamed_addr #1 align 2 { entry: ret i32 1 } ; CHECK-NOT: define internal i32 @_ZN1A3barEf( define internal i32 @_ZN1A3barEf(ptr nocapture readnone %this, float) unnamed_addr #1 align 2 { entry: ret i32 2 } ; CHECK: define internal i32 @_ZN1B3fooEi( define internal i32 @_ZN1B3fooEi(ptr nocapture readnone %this, i32) unnamed_addr #1 align 2 { entry: ret i32 3 } ; CHECK-NOT: define internal i32 @_ZN1B3barEf( define internal i32 @_ZN1B3barEf(ptr nocapture readnone %this, float) unnamed_addr #1 align 2 { entry: ret i32 4 } define hidden void @_ZN1AC2Ev(ptr nocapture %this) { entry: store ptr getelementptr inbounds ({ [4 x ptr] }, ptr @_ZTV1A, i64 0, inrange i32 0, i64 2), ptr %this, align 8 ret void } define hidden void @_ZN1BC2Ev(ptr nocapture %this) { entry: store ptr getelementptr inbounds ({ [4 x ptr] }, ptr @_ZTV1B, i64 0, inrange i32 0, i64 2), ptr %this, align 8 ret void } define hidden i32 @test(ptr %p, i64 %q.coerce0, i64 %q.coerce1) { entry: %0 = getelementptr inbounds i8, ptr %p, i64 %q.coerce1 %1 = and i64 %q.coerce0, 1 %memptr.isvirtual = icmp eq i64 %1, 0 br i1 %memptr.isvirtual, label %memptr.nonvirtual, label %memptr.virtual memptr.virtual: ; preds = %entry %vtable = load ptr, ptr %0, align 8 %2 = add i64 %q.coerce0, -1 %3 = getelementptr i8, ptr %vtable, i64 %2, !nosanitize !12 %4 = tail call { ptr, i1 } @llvm.type.checked.load(ptr %3, i32 0, metadata !"_ZTSM1AFiiE.virtual"), !nosanitize !12 %5 = extractvalue { ptr, i1 } %4, 0, !nosanitize !12 br label %memptr.end memptr.nonvirtual: ; preds = %entry %memptr.nonvirtualfn = inttoptr i64 %q.coerce0 to ptr br label %memptr.end memptr.end: ; preds = %memptr.nonvirtual, %memptr.virtual %6 = phi ptr [ %5, %memptr.virtual ], [ %memptr.nonvirtualfn, %memptr.nonvirtual ] %call = tail call i32 %6(ptr %0, i32 42) ret i32 %call } declare { ptr, i1 } @llvm.type.checked.load(ptr, i32, metadata) !llvm.module.flags = !{!7} !0 = !{i64 16, !"_ZTS1A"} !1 = !{i64 16, !"_ZTSM1AFiiE.virtual"} !2 = !{i64 24, !"_ZTSM1AFifE.virtual"} !3 = !{i64 2} !4 = !{i64 16, !"_ZTS1B"} !5 = !{i64 16, !"_ZTSM1BFiiE.virtual"} !6 = !{i64 24, !"_ZTSM1BFifE.virtual"} !7 = !{i32 1, !"Virtual Function Elim", i32 1} !12 = !{}