[PATCH] D145293: [GlobalOpt] Don't replace the aliasee if it has other references

[DianQK via Phabricator via llvm-commits]

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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D145293

Files:
  llvm/lib/Transforms/IPO/GlobalOpt.cpp
  llvm/test/Transforms/GlobalOpt/alias-used.ll


Index: llvm/test/Transforms/GlobalOpt/alias-used.ll
===================================================================
--- llvm/test/Transforms/GlobalOpt/alias-used.ll
+++ llvm/test/Transforms/GlobalOpt/alias-used.ll
@@ -2,15 +2,16 @@
 
 @c = dso_local global i8 42
 
+; CHECK: @i = internal global i8 42
 @i = internal global i8 42
-; CHECK: @ia = internal global i8 42
+; CHECK-DAG: @ia = internal alias i8, ptr @i
 @ia = internal alias i8, ptr @i
 
 @llvm.used = appending global [3 x ptr] [ptr @fa, ptr @f, ptr @ca], section "llvm.metadata"
 ; CHECK-DAG: @llvm.used = appending global [3 x ptr] [ptr @ca, ptr @f, ptr @fa], section "llvm.metadata"
 
 @llvm.compiler.used = appending global [4 x ptr] [ptr @fa3, ptr @fa, ptr @ia, ptr @i], section "llvm.metadata"
-; CHECK-DAG: @llvm.compiler.used = appending global [2 x ptr] [ptr @fa3, ptr @ia], section "llvm.metadata"
+; CHECK-DAG: @llvm.compiler.used = appending global [3 x ptr] [ptr @fa3, ptr @i, ptr @ia], section "llvm.metadata"
 
 @sameAsUsed = global [3 x ptr] [ptr @fa, ptr @f, ptr @ca]
 ; CHECK-DAG: @sameAsUsed = local_unnamed_addr global [3 x ptr] [ptr @f, ptr @f, ptr @c]
Index: llvm/lib/Transforms/IPO/GlobalOpt.cpp
===================================================================
--- llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2200,11 +2200,11 @@
   return V.hasNUsesOrMore(N);
 }
 
-static bool mayHaveOtherReferences(GlobalAlias &GA, const LLVMUsed &U) {
-  if (!GA.hasLocalLinkage())
+static bool mayHaveOtherReferences(GlobalValue &GV, const LLVMUsed &U) {
+  if (!GV.hasLocalLinkage())
     return true;
 
-  return U.usedCount(&GA) || U.compilerUsedCount(&GA);
+  return U.usedCount(&GV) || U.compilerUsedCount(&GV);
 }
 
 static bool hasUsesToReplace(GlobalAlias &GA, const LLVMUsed &U,
@@ -2218,15 +2218,16 @@
   if (!mayHaveOtherReferences(GA, U))
     return Ret;
 
-  // If the aliasee has internal linkage, give it the name and linkage
-  // of the alias, and delete the alias.  This turns:
+  // If the aliasee has internal linkage and no other references (e.g.,
+  // @llvm.used, @llvm.compiler.used), give it the name and linkage of the
+  // alias, and delete the alias. This turns:
   //   define internal ... @f(...)
   //   @a = alias ... @f
   // into:
   //   define ... @a(...)
   Constant *Aliasee = GA.getAliasee();
   GlobalValue *Target = cast<GlobalValue>(Aliasee->stripPointerCasts());
-  if (!Target->hasLocalLinkage())
+  if (mayHaveOtherReferences(*Target, U))
     return Ret;
 
   // Do not perform the transform if multiple aliases potentially target the


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