[CGData][GMF] Skip merging unnamed functions (#148995)

Skip merging unnamed functions to fix an assertion issue, since unnamed
functions would otherwise receive the same merged name --
https://github.com/llvm/llvm-project/blob/main/llvm/lib/CodeGen/GlobalMergeFunctions.cpp#L191

Author: kyulee-com

llvm/lib/CodeGen/GlobalMergeFunctions.cpp

@@ -95,6 +95,10 @@ bool isEligibleFunction(Function *F) {
   if (F->getCallingConv() == CallingConv::SwiftTail)
     return false;
 
+  // Unnamed functions are skipped for simplicity.
+  if (!F->hasName())
+    return false;
+
   // If function contains callsites with musttail, if we merge
   // it, the merged function will have the musttail callsite, but
   // the number of parameters can change, thus the parameter count

llvm/test/CodeGen/AArch64/cgdata-no-merge-unnamed.ll

@@ -0,0 +1,32 @@
+; This test checks if two similar functions, @0 and @1, are not merged as they are unnamed.
+
+; RUN: opt -mtriple=arm64-apple-darwin -S --passes=global-merge-func %s | FileCheck %s
+; RUN: llc -mtriple=arm64-apple-darwin -enable-global-merge-func=true < %s | FileCheck %s
+
+; CHECK-NOT: .Tgm
+
+@g = external local_unnamed_addr global [0 x i32], align 4
+@g1 = external global i32, align 4
+@g2 = external global i32, align 4
+
+define i32 @0(i32 %a) {
+entry:
+  %idxprom = sext i32 %a to i64
+  %arrayidx = getelementptr inbounds [0 x i32], [0 x i32]* @g, i64 0, i64 %idxprom
+  %0 = load i32, i32* %arrayidx, align 4
+  %1 = load volatile i32, i32* @g1, align 4
+  %mul = mul nsw i32 %1, %0
+  %add = add nsw i32 %mul, 1
+  ret i32 %add
+}
+
+define i32 @1(i32 %a) {
+entry:
+  %idxprom = sext i32 %a to i64
+  %arrayidx = getelementptr inbounds [0 x i32], [0 x i32]* @g, i64 0, i64 %idxprom
+  %0 = load i32, i32* %arrayidx, align 4
+  %1 = load volatile i32, i32* @g2, align 4
+  %mul = mul nsw i32 %1, %0
+  %add = add nsw i32 %mul, 1
+  ret i32 %add
+}