[llvm-branch-commits] [llvm] 1b09e84 - Revert "[llvm][GlobalOpt] Preserve COMDATs for Dead GVs (#222720)"

[via llvm-branch-commits]

Author: Kewen Meng
Date: 2026-10-20T21:33:39-07:00
New Revision: 1b09e84d13a4132b3cfb081aa20add9881243967

URL: https://github.com/llvm/llvm-project/commit/1b09e84d13a4132b3cfb081aa20add9881243967
DIFF: https://github.com/llvm/llvm-project/commit/1b09e84d13a4132b3cfb081aa20add9881243967.diff

LOG: Revert "[llvm][GlobalOpt] Preserve COMDATs for Dead GVs (#222720)"

This reverts commit fde5c72be4db40cc567d0eedf2bc0646dca4050a.

Added: 
    

Modified: 
    llvm/include/llvm/IR/GlobalValue.h
    llvm/lib/IR/Globals.cpp
    llvm/lib/Transforms/IPO/GlobalOpt.cpp

Removed: 
    llvm/test/Transforms/GlobalOpt/deadfunction-comdat.ll
    llvm/test/Transforms/GlobalOpt/deadglobal-comdat.ll


################################################################################
diff  --git a/llvm/include/llvm/IR/GlobalValue.h b/llvm/include/llvm/IR/GlobalValue.h
index 8ab220cc322da3..79e45ef51367c1 100644
--- a/llvm/include/llvm/IR/GlobalValue.h
+++ b/llvm/include/llvm/IR/GlobalValue.h
@@ -251,14 +251,6 @@ class GlobalValue : public Constant {
                            static_cast<const GlobalValue *>(this)->getComdat());
   }
 
-  /// Returns true if the \c GlobalValue is the leader of its \c Comdat group.
-  /// A \c GlobalValue is considered a \c Comdat leader if it has a \c Comdat
-  /// and its name matches the name of the \c Comdat group in the symbol table.
-  /// For a \c GlobalAlias, this resolves through the alias to inspect the
-  /// aliasee's \c Comdat, treating the alias as the leader if its own name
-  /// matches the \c Comdat group name.
-  LLVM_ABI bool isComdatLeader() const;
-
   VisibilityTypes getVisibility() const { return VisibilityTypes(Visibility); }
   bool hasDefaultVisibility() const { return Visibility == DefaultVisibility; }
   bool hasHiddenVisibility() const { return Visibility == HiddenVisibility; }

diff  --git a/llvm/lib/IR/Globals.cpp b/llvm/lib/IR/Globals.cpp
index c8ccff9f90080a..3428f662e9120f 100644
--- a/llvm/lib/IR/Globals.cpp
+++ b/llvm/lib/IR/Globals.cpp
@@ -284,12 +284,6 @@ const Comdat *GlobalValue::getComdat() const {
   return cast<GlobalObject>(this)->getComdat();
 }
 
-bool GlobalValue::isComdatLeader() const {
-  if (hasComdat())
-    return getParent()->getComdatSymbolTable().contains(getName());
-  return false;
-}
-
 void GlobalObject::setComdat(Comdat *C) {
   if (ObjComdat)
     ObjComdat->removeUser(this);

diff  --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 5941d5f3a51e30..f65f488b9bbb66 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1323,27 +1323,9 @@ deleteIfDead(GlobalValue &GV,
   if (!GV.isDiscardableIfUnused() && !GV.isDeclaration())
     return false;
 
-  if (auto *C = GV.getComdat()) {
-    auto IsComdatLeaderWithUses = false;
-    if (GV.isComdatLeader()) {
-      if (C->getUsers().size() > 1) {
-        IsComdatLeaderWithUses = true;
-      } else if (auto *GA = dyn_cast<GlobalAlias>(&GV)) {
-        if (auto *GO = dyn_cast<GlobalObject>(GA->getAliasee())) {
-          GO->removeDeadConstantUsers();
-          // The alias leader has uses if the aliasee cannot be discarded, or if
-          // the aliasee has uses other than this alias.
-          IsComdatLeaderWithUses = !GO->hasOneUse();
-        } else {
-          IsComdatLeaderWithUses = true;
-        }
-      }
-    }
-
-    if (IsComdatLeaderWithUses ||
-        (!GV.hasInternalLinkage() && NotDiscardableComdats.count(C)))
+  if (const Comdat *C = GV.getComdat())
+    if (!GV.hasLocalLinkage() && NotDiscardableComdats.count(C))
       return false;
-  }
 
   bool Dead;
   if (auto *F = dyn_cast<Function>(&GV))

diff  --git a/llvm/test/Transforms/GlobalOpt/deadfunction-comdat.ll b/llvm/test/Transforms/GlobalOpt/deadfunction-comdat.ll
deleted file mode 100644
index 02b483f2aa8b64..00000000000000
--- a/llvm/test/Transforms/GlobalOpt/deadfunction-comdat.ll
+++ /dev/null
@@ -1,52 +0,0 @@
-; RUN: opt < %s -passes=globalopt -S | FileCheck %s
-
-target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-pc-windows-msvc"
-
-$foo = comdat any
-$trulydead = comdat any
-$aliasleader = comdat any
-
-; CHECK: @aliasleader
- at aliasleader = internal alias void (), ptr @aliasee
-
-; CHECK: @foo
-define internal void @foo() comdat {
-  ret void
-}
-
-; CHECK: @bar
-define internal void @bar() #0 comdat($foo) {
-  ret void
-}
-
-define void @zed()  {
-  call void @bar()
-  ret void
-}
-
-; CHECK-NOT: @trulydead
-define internal void @trulydead() comdat {
-  ret void
-}
-
-; CHECK-NOT: @trulydead2
-define internal void @trulydead2() comdat($trulydead) {
-  ret void
-}
-
-; CHECK: define internal void @aliasee
-define internal void @aliasee() comdat($aliasleader) {
-    ret void
-}
-
-define void @call_aliasee() { 
-    call void @aliasee()
-    ret void
-}
-
-define i32 @main() {
-  ret i32 0
-}
-
-attributes #0 = { noinline }
\ No newline at end of file

diff  --git a/llvm/test/Transforms/GlobalOpt/deadglobal-comdat.ll b/llvm/test/Transforms/GlobalOpt/deadglobal-comdat.ll
deleted file mode 100644
index e1f99975a057e8..00000000000000
--- a/llvm/test/Transforms/GlobalOpt/deadglobal-comdat.ll
+++ /dev/null
@@ -1,22 +0,0 @@
-; RUN: opt < %s -passes=globalopt -S | FileCheck %s
-
-target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-pc-windows-msvc"
-
-; CHECK: $x
-$x = comdat any
-
-; CHECK-NOT: $trulydeadg
-$trulydeadg = comdat any
-
-; CHECK: @g
- at g = internal global i32 0, comdat($x)
-; CHECK: @g2
- at g2 = global i32 0, comdat($x)
-; CHECK: @x
- at x = internal alias i32, ptr @g
-
-; CHECK-NOT: @trulydeadg
- at trulydeadg = internal alias i32, ptr @deadg
-; CHECK-NOT: @deadg
- at deadg = internal global i32 0, comdat($trulydeadg)
\ No newline at end of file