1 files changed, 120 insertions, 0 deletions
diff --git a/llvm/test/Transforms/GlobalDCE/virtual-functions-derived-pointer-call.ll b/llvm/test/Transforms/GlobalDCE/virtual-functions-derived-pointer-call.ll
new file mode 100644
index 00000000000..62b5b8d3730
--- /dev/null
+++ b/llvm/test/Transforms/GlobalDCE/virtual-functions-derived-pointer-call.ll
@@ -0,0 +1,120 @@
+
+; RUN: opt < %s -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(B *p, int (B::*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 (B::*q)(int)", so the call could only be dispatched to
+; B::foo. It can't be dispatched to A::bar or B::bar as the function pointer
+; does not match, and it can't be dispatched to A::foo as the object type
+; doesn't match, so those can be removed.
+
+%struct.A = type { i32 (...)** }
+%struct.B = type { %struct.A }
+
+; CHECK: @_ZTV1A = internal unnamed_addr constant { [4 x i8*] } zeroinitializer
+@_ZTV1A = internal unnamed_addr constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* null, i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A3fooEi to i8*), i8* bitcast (i32 (%struct.A*, float)* @_ZN1A3barEf to i8*)] }, align 8, !type !0, !type !1, !type !2, !vcall_visibility !3
+; CHECK: @_ZTV1B = internal unnamed_addr constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* null, i8* bitcast (i32 (%struct.B*, i32)* @_ZN1B3fooEi to i8*), i8* null] }
+@_ZTV1B = internal unnamed_addr constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* null, i8* bitcast (i32 (%struct.B*, i32)* @_ZN1B3fooEi to i8*), i8* bitcast (i32 (%struct.B*, float)* @_ZN1B3barEf to i8*)] }, align 8, !type !0, !type !1, !type !2, !type !4, !type !5, !type !6, !vcall_visibility !3
+
+
+; CHECK-NOT: define internal i32 @_ZN1A3fooEi(
+define internal i32 @_ZN1A3fooEi(%struct.A* nocapture readnone %this, i32) unnamed_addr #1 align 2 {
+entry:
+  ret i32 1
+}
+
+; CHECK-NOT: define internal i32 @_ZN1A3barEf(
+define internal i32 @_ZN1A3barEf(%struct.A* nocapture readnone %this, float) unnamed_addr #1 align 2 {
+entry:
+  ret i32 2
+}
+
+; CHECK: define internal i32 @_ZN1B3fooEi(
+define internal i32 @_ZN1B3fooEi(%struct.B* nocapture readnone %this, i32) unnamed_addr #1 align 2 {
+entry:
+  ret i32 3
+}
+
+; CHECK-NOT: define internal i32 @_ZN1B3barEf(
+define internal i32 @_ZN1B3barEf(%struct.B* nocapture readnone %this, float) unnamed_addr #1 align 2 {
+entry:
+  ret i32 4
+}
+
+
+define hidden void @_ZN1AC2Ev(%struct.A* nocapture %this) {
+entry:
+  %0 = getelementptr inbounds %struct.A, %struct.A* %this, i64 0, i32 0
+  store i32 (...)** bitcast (i8** getelementptr inbounds ({ [4 x i8*] }, { [4 x i8*] }* @_ZTV1A, i64 0, inrange i32 0, i64 2) to i32 (...)**), i32 (...)*** %0, align 8
+  ret void
+}
+
+define hidden void @_ZN1BC2Ev(%struct.B* nocapture %this) {
+entry:
+  %0 = getelementptr inbounds %struct.B, %struct.B* %this, i64 0, i32 0, i32 0
+  store i32 (...)** bitcast (i8** getelementptr inbounds ({ [4 x i8*] }, { [4 x i8*] }* @_ZTV1B, i64 0, inrange i32 0, i64 2) to i32 (...)**), i32 (...)*** %0, align 8
+  ret void
+}
+
+define hidden i32 @test(%struct.B* %p, i64 %q.coerce0, i64 %q.coerce1) {
+entry:
+  %0 = bitcast %struct.B* %p to i8*
+  %1 = getelementptr inbounds i8, i8* %0, i64 %q.coerce1
+  %this.adjusted = bitcast i8* %1 to %struct.B*
+  %2 = and i64 %q.coerce0, 1
+  %memptr.isvirtual = icmp eq i64 %2, 0
+  br i1 %memptr.isvirtual, label %memptr.nonvirtual, label %memptr.virtual
+
+memptr.virtual:                                   ; preds = %entry
+  %3 = bitcast i8* %1 to i8**
+  %vtable = load i8*, i8** %3, align 8
+  %4 = add i64 %q.coerce0, -1
+  %5 = getelementptr i8, i8* %vtable, i64 %4, !nosanitize !12
+  %6 = tail call { i8*, i1 } @llvm.type.checked.load(i8* %5, i32 0, metadata !"_ZTSM1BFiiE.virtual"), !nosanitize !12
+  %7 = extractvalue { i8*, i1 } %6, 0, !nosanitize !12
+  %memptr.virtualfn = bitcast i8* %7 to i32 (%struct.B*, i32)*, !nosanitize !12
+  br label %memptr.end
+
+memptr.nonvirtual:                                ; preds = %entry
+  %memptr.nonvirtualfn = inttoptr i64 %q.coerce0 to i32 (%struct.B*, i32)*
+  br label %memptr.end
+
+memptr.end:                                       ; preds = %memptr.nonvirtual, %memptr.virtual
+  %8 = phi i32 (%struct.B*, i32)* [ %memptr.virtualfn, %memptr.virtual ], [ %memptr.nonvirtualfn, %memptr.nonvirtual ]
+  %call = tail call i32 %8(%struct.B* %this.adjusted, i32 42)
+  ret i32 %call
+}
+
+declare { i8*, i1 } @llvm.type.checked.load(i8*, i32, metadata)
+
+!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"}
+!12 = !{}