[llvm] 617ba83 - [GlobalOpt] Preserve Address Space when recreating GV (#171211)

[via llvm-commits]

Author: Evgenii Podkorytov
Date: 2025-12-10T15:10:40+01:00
New Revision: 617ba837eecf39a65ef4183c36892f8bf58a74cc

URL: https://github.com/llvm/llvm-project/commit/617ba837eecf39a65ef4183c36892f8bf58a74cc
DIFF: https://github.com/llvm/llvm-project/commit/617ba837eecf39a65ef4183c36892f8bf58a74cc.diff

LOG: [GlobalOpt] Preserve Address Space when recreating GV (#171211)

Fix for GlobalOpt pass: preserve Address Space when recreating GV
This fix prevents dropping `addrspace(1)` in the following code snippet
(see modified LIT-test) for `@llvm.compiler.used`:

Before global-opt
```
@_ZM2C = internal addrspace(1) global %struct.FakeDeviceGlobal zeroinitializer, align 8
@_ZL1C = internal addrspace(1) global %struct.FakeDeviceGlobal zeroinitializer, align 8

@llvm.compiler.used = appending addrspace(1) global [2 x ptr addrspace(4)] [ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZM2C to ptr addrspace(4)), ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZL1C to ptr addrspace(4))]
```

After global-opt
```
@_ZM2C = internal addrspace(1) global %struct.FakeDeviceGlobal zeroinitializer, align 8
@_ZL1C = internal addrspace(1) global %struct.FakeDeviceGlobal zeroinitializer, align 8

@llvm.compiler.used = appending global [2 x ptr addrspace(4)] [ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZM2C to ptr addrspace(4)), ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZL1C to ptr addrspace(4))]
```

With proposed fix `@llvm.compiler.used` will be re-created with
preserving original `addrspace(1)` as:
```
@llvm.compiler.used = appending addrspace(1) global [2 x ptr addrspace(4)] [ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZM2C to ptr addrspace(4)), ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZL1C to ptr addrspace(4))]
```

Added: 
    

Modified: 
    llvm/lib/Transforms/IPO/GlobalOpt.cpp
    llvm/test/Transforms/GlobalOpt/global-opt-addrspace.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 66b95fc7bde5f..664722244699d 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2144,9 +2144,10 @@ static void setUsedInitializer(GlobalVariable &V,
 
   Module *M = V.getParent();
   V.removeFromParent();
-  GlobalVariable *NV =
-      new GlobalVariable(*M, ATy, false, GlobalValue::AppendingLinkage,
-                         ConstantArray::get(ATy, UsedArray), "");
+  GlobalVariable *NV = new GlobalVariable(
+      *M, ATy, false, GlobalValue::AppendingLinkage,
+      ConstantArray::get(ATy, UsedArray), "", nullptr,
+      GlobalVariable::NotThreadLocal, V.getType()->getAddressSpace());
   NV->takeName(&V);
   NV->setSection("llvm.metadata");
   delete &V;

diff  --git a/llvm/test/Transforms/GlobalOpt/global-opt-addrspace.ll b/llvm/test/Transforms/GlobalOpt/global-opt-addrspace.ll
index 9df8a4bfbfae1..724402f5c663e 100644
--- a/llvm/test/Transforms/GlobalOpt/global-opt-addrspace.ll
+++ b/llvm/test/Transforms/GlobalOpt/global-opt-addrspace.ll
@@ -8,9 +8,9 @@
 @_ZM2C = internal addrspace(1) global %struct.FakeDeviceGlobal zeroinitializer, align 8
 @_ZL1C = internal addrspace(1) global %struct.FakeDeviceGlobal zeroinitializer, align 8
 
- at llvm.compiler.used = appending global [2 x ptr addrspace(4)] [ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZM2C to ptr addrspace(4)), ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZL1C to ptr addrspace(4))]
+ at llvm.compiler.used = appending addrspace(1) global [2 x ptr addrspace(4)] [ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZM2C to ptr addrspace(4)), ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZL1C to ptr addrspace(4))]
 
-; CHECK: @llvm.compiler.used = appending global [2 x ptr addrspace(4)] [ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZL1C to ptr addrspace(4)), ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZM2C to ptr addrspace(4))]
+; CHECK: @llvm.compiler.used = appending addrspace(1) global [2 x ptr addrspace(4)] [ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZL1C to ptr addrspace(4)), ptr addrspace(4) addrspacecast (ptr addrspace(1) @_ZM2C to ptr addrspace(4))]
 
 define weak_odr dso_local void @foo() {
 entry: