[llvm] llvm-reduce: Reduce externally_initialized (PR #133859)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm created https://github.com/llvm/llvm-project/pull/133859

Not sure this is the right place to put it. This is a property
of GlobalVariable, not GlobalValue. But the ReduceGlobalVars
reduction tries to delete the value entirely.

>From ca1e66b7e8608ff91d57f7d3a4a357ffa4912ceb Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Tue, 1 Apr 2025 12:20:59 +0700
Subject: [PATCH] llvm-reduce: Reduce externally_initialized

Not sure this is the right place to put it. This is a property
of GlobalVariable, not GlobalValue. But the ReduceGlobalVars
reduction tries to delete the value entirely.
---
 .../llvm-reduce/reduce-externally-initialized.ll      | 11 +++++++++++
 llvm/tools/llvm-reduce/deltas/ReduceGlobalValues.cpp  |  8 ++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 llvm/test/tools/llvm-reduce/reduce-externally-initialized.ll

diff --git a/llvm/test/tools/llvm-reduce/reduce-externally-initialized.ll b/llvm/test/tools/llvm-reduce/reduce-externally-initialized.ll
new file mode 100644
index 0000000000000..edd98fa60e5fe
--- /dev/null
+++ b/llvm/test/tools/llvm-reduce/reduce-externally-initialized.ll
@@ -0,0 +1,11 @@
+; RUN: llvm-reduce -abort-on-invalid-reduction --delta-passes=global-values --test FileCheck --test-arg --check-prefix=INTERESTING --test-arg %s --test-arg --input-file %s -o %t.0
+; RUN: FileCheck --implicit-check-not=define --check-prefix=RESULT %s < %t.0
+
+; INTERESTING: @externally_initialized_keep = externally_initialized global i32 0
+; INTERESTING: @externally_initialized_drop
+
+; RESULT: @externally_initialized_keep = externally_initialized global i32 0, align 4
+; RESULT: @externally_initialized_drop = global i32 1, align 4
+ at externally_initialized_keep = externally_initialized global i32 0, align 4
+ at externally_initialized_drop = externally_initialized global i32 1, align 4
+
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceGlobalValues.cpp b/llvm/tools/llvm-reduce/deltas/ReduceGlobalValues.cpp
index 577e0f5d16b63..e56876c38032e 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceGlobalValues.cpp
+++ b/llvm/tools/llvm-reduce/deltas/ReduceGlobalValues.cpp
@@ -64,5 +64,13 @@ void llvm::reduceGlobalValuesDeltaPass(Oracle &O, ReducerWorkItem &Program) {
       if (IsImplicitDSOLocal)
         GV.setDSOLocal(false);
     }
+
+    // TODO: Should this go in a separate reduction?
+    if (auto *GVar = dyn_cast<GlobalVariable>(&GV)) {
+      if (GVar->isExternallyInitialized() && !O.shouldKeep())
+        GVar->setExternallyInitialized(false);
+
+      // TODO: Reduce code model
+    }
   }
 }