[PATCH] D120006: [GlobalDCE] [VFE] Avoid dropping vfunc dependencies when an invalid vtable entry is present

[Kuba (Brecka) Mracek via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG6b53ad298e95: [GlobalDCE] [VFE] Avoid dropping vfunc dependencies when an invalid vtable… (authored by kubamracek).

Changed prior to commit:
  https://reviews.llvm.org/D120006?vs=409483&id=409848#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D120006/new/

https://reviews.llvm.org/D120006

Files:
  llvm/lib/Transforms/IPO/GlobalDCE.cpp
  llvm/test/Transforms/GlobalDCE/virtual-functions-nonptr.ll
  llvm/test/Transforms/GlobalDCE/virtual-functions-null.ll


Index: llvm/test/Transforms/GlobalDCE/virtual-functions-null.ll
===================================================================
--- llvm/test/Transforms/GlobalDCE/virtual-functions-null.ll
+++ llvm/test/Transforms/GlobalDCE/virtual-functions-null.ll
@@ -20,7 +20,7 @@
 ]}, align 8, !type !{i64 0, !"vfunc1.type"}, !type !{i64 8, !"vfunc2.type"}, !vcall_visibility !{i64 2}
 
 ; CHECK:      @vtableB = internal unnamed_addr constant { [2 x i8*] } { [2 x i8*] [
-; CHECK-SAME:   i8* null,
+; CHECK-SAME:   i8* bitcast (void ()* @vfunc1 to i8*),
 ; CHECK-SAME:   i8* bitcast (void ()* @vfunc2 to i8*)
 ; CHECK-SAME: ] }, align 8
 
Index: llvm/test/Transforms/GlobalDCE/virtual-functions-nonptr.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/GlobalDCE/virtual-functions-nonptr.ll
@@ -0,0 +1,44 @@
+; RUN: opt < %s -globaldce -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+declare { i8*, i1 } @llvm.type.checked.load(i8*, i32, metadata)
+
+ at vtableA = internal unnamed_addr constant { [2 x i32] } { [2 x i32] [
+  i32 0,
+  i32 trunc (i64 sub (i64 ptrtoint (void ()* @vfunc2 to i64), i64 ptrtoint ({ [2 x i32] }* @vtableA to i64)) to i32)
+]}, align 8, !type !{i64 0, !"vfunc1.type"}, !type !{i64 4, !"vfunc2.type"}, !vcall_visibility !{i64 2}
+
+; CHECK:      @vtableA = internal unnamed_addr constant { [2 x i32] } { [2 x i32] [
+; CHECK-SAME:   i32 0,
+; CHECK-SAME:   i32 trunc (i64 sub (i64 ptrtoint (void ()* @vfunc2 to i64), i64 ptrtoint ({ [2 x i32] }* @vtableA to i64)) to i32)
+; CHECK-SAME: ] }, align 8
+
+ at vtableB = internal unnamed_addr constant { [2 x i32] } { [2 x i32] [
+  i32 trunc (i64 sub (i64 ptrtoint (void ()* @vfunc1 to i64), i64 ptrtoint ({ [2 x i32] }* @vtableB to i64)) to i32),
+  i32 trunc (i64 sub (i64 ptrtoint (void ()* @vfunc2 to i64), i64 ptrtoint ({ [2 x i32] }* @vtableB to i64)) to i32)
+]}, align 8, !type !{i64 0, !"vfunc1.type"}, !type !{i64 4, !"vfunc2.type"}, !vcall_visibility !{i64 2}
+
+; CHECK:      @vtableB = internal unnamed_addr constant { [2 x i32] } { [2 x i32] [
+; CHECK-SAME:   i32 trunc (i64 sub (i64 ptrtoint (void ()* @vfunc1 to i64), i64 ptrtoint ({ [2 x i32] }* @vtableB to i64)) to i32),
+; CHECK-SAME:   i32 trunc (i64 sub (i64 ptrtoint (void ()* @vfunc2 to i64), i64 ptrtoint ({ [2 x i32] }* @vtableB to i64)) to i32)
+; CHECK-SAME: ] }, align 8
+
+define internal void @vfunc1() {
+  ret void
+}
+
+define internal void @vfunc2() {
+  ret void
+}
+
+define void @main() {
+  %1 = ptrtoint { [2 x i32] }* @vtableA to i64 ; to keep @vtableA alive
+  %2 = ptrtoint { [2 x i32] }* @vtableB to i64 ; to keep @vtableB alive
+  %3 = tail call { i8*, i1 } @llvm.type.checked.load(i8* null, i32 0, metadata !"vfunc1.type")
+  %4 = tail call { i8*, i1 } @llvm.type.checked.load(i8* null, i32 0, metadata !"vfunc2.type")
+  ret void
+}
+
+!999 = !{i32 1, !"Virtual Function Elim", i32 1}
+!llvm.module.flags = !{!999}
Index: llvm/lib/Transforms/IPO/GlobalDCE.cpp
===================================================================
--- llvm/lib/Transforms/IPO/GlobalDCE.cpp
+++ llvm/lib/Transforms/IPO/GlobalDCE.cpp
@@ -214,14 +214,14 @@
     if (!Ptr) {
       LLVM_DEBUG(dbgs() << "can't find pointer in vtable!\n");
       VFESafeVTables.erase(VTable);
-      return;
+      continue;
     }
 
     auto Callee = dyn_cast<Function>(Ptr->stripPointerCasts());
     if (!Callee) {
       LLVM_DEBUG(dbgs() << "vtable entry is not function pointer!\n");
       VFESafeVTables.erase(VTable);
-      return;
+      continue;
     }
 
     LLVM_DEBUG(dbgs() << "vfunc dep " << Caller->getName() << " -> "


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D120006.409848.patch
Type: text/x-patch
Size: 3653 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20220218/37f354f7/attachment-0001.bin>