convert external globals with no usage to internal linkage to be removed by globaldce, fix tests

Author: kmpeng

llvm/lib/Target/DirectX/DXILFinalizeLinkage.cpp

@@ -20,13 +20,13 @@ using namespace llvm;
 static bool finalizeLinkage(Module &M) {
   bool MadeChange = false;
 
-  // Convert private global variables to internal linkage.
-  for (GlobalVariable &GV : M.globals()) {
-    if (GV.hasPrivateLinkage()) {
+  // Convert private globals and external globals with no usage to internal
+  // linkage.
+  for (GlobalVariable &GV : M.globals())
+    if (GV.hasPrivateLinkage() || (GV.hasExternalLinkage() && GV.use_empty())) {
       GV.setLinkage(GlobalValue::InternalLinkage);
       MadeChange = true;
     }
-  }
 
   SmallVector<Function *> Funcs;
 

llvm/test/CodeGen/DirectX/finalize_linkage.ll

@@ -4,7 +4,14 @@
 target triple = "dxilv1.5-pc-shadermodel6.5-compute"
 
 ; DXILFinalizeLinkage changes linkage of all functions that are hidden to
-; internal, and converts private global variables to internal linkage.
+; internal, converts private global variables to internal linkage, and removes
+; unused global variables.
+
+; CHECK-NOT: @aTile
+@aTile = hidden addrspace(3) global [4 x [1 x i32]] zeroinitializer, align 4
+
+; CHECK-NOT: @bTile
+@bTile = hidden addrspace(3) global [1 x <1 x i32>] zeroinitializer, align 4
 
 ; CHECK: @switch.table = internal unnamed_addr constant [4 x i32]
 @switch.table = private unnamed_addr constant [4 x i32] [i32 1, i32 257, i32 65793, i32 16843009], align 4
@@ -27,6 +34,17 @@ target triple = "dxilv1.5-pc-shadermodel6.5-compute"
 ; CHECK: @hidden_var = hidden global i32
 @hidden_var = hidden global i32 1, align 4
 
+define void @anchor_function() #0 {
+entry:
+  %0 = load i32, ptr @switch.table, align 4
+  %1 = load [3 x float], ptr @private_array, align 4
+  %2 = load i32, ptr @private_var, align 4
+  %3 = load i32, ptr @internal_var, align 4
+  %4 = load i32, ptr @external_var, align 4
+  %5 = load i32, ptr @hidden_var, align 4
+  ret void
+}
+
 ; CHECK-NOT: define internal void @"?f1@@YAXXZ"()
 define void @"?f1@@YAXXZ"() #0 {
 entry:

llvm/test/CodeGen/DirectX/scalar-data.ll

@@ -1,4 +1,4 @@
-; RUN: llc %s -mtriple=dxil-pc-shadermodel6.3-library --filetype=asm -o - | FileCheck %s
+; RUN: opt -S -passes='dxil-data-scalarization,dxil-flatten-arrays' -mtriple=dxil-unknown-shadermodel6.5-compute %s | FileCheck %s
 
 ; Make sure we don't touch arrays without vectors and that can recurse and flatten multiple-dimension arrays of vectors
 

llvm/test/tools/dxil-dis/opaque-value_as_metadata.ll

@@ -7,6 +7,7 @@ target triple = "dxil-unknown-shadermodel6.7-library"
 @CBV = external constant %"$Globals"
 
 define void @main() #0 {
+  %1 = load float, ptr @CBV, align 4
   ret void
 }