[PATCH] D41705: Place undefined globals in .bss instead of .data

[Eli Friedman via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL324424: Place undefined globals in .bss instead of .data (authored by efriedma, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D41705?vs=132388&id=133092#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D41705

Files:
  llvm/trunk/lib/Target/TargetLoweringObjectFile.cpp
  llvm/trunk/test/CodeGen/ARM/memfunc.ll
  llvm/trunk/test/CodeGen/X86/undef-globals-bss.ll


Index: llvm/trunk/lib/Target/TargetLoweringObjectFile.cpp
===================================================================
--- llvm/trunk/lib/Target/TargetLoweringObjectFile.cpp
+++ llvm/trunk/lib/Target/TargetLoweringObjectFile.cpp
@@ -52,11 +52,24 @@
   delete Mang;
 }
 
+static bool isNullOrUndef(const Constant *C) {
+  // Check that the constant isn't all zeros or undefs.
+  if (C->isNullValue() || isa<UndefValue>(C))
+    return true;
+  if (!isa<ConstantAggregate>(C))
+    return false;
+  for (auto Operand : C->operand_values()) {
+    if (!isNullOrUndef(cast<Constant>(Operand)))
+      return false;
+  }
+  return true;
+}
+
 static bool isSuitableForBSS(const GlobalVariable *GV, bool NoZerosInBSS) {
   const Constant *C = GV->getInitializer();
 
   // Must have zero initializer.
-  if (!C->isNullValue())
+  if (!isNullOrUndef(C))
     return false;
 
   // Leave constant zeros in readonly constant sections, so they can be shared.
Index: llvm/trunk/test/CodeGen/X86/undef-globals-bss.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/undef-globals-bss.ll
+++ llvm/trunk/test/CodeGen/X86/undef-globals-bss.ll
@@ -0,0 +1,12 @@
+; RUN: llc < %s | FileCheck %s
+target triple = "x86_64-apple-darwin"
+
+; CHECK: .zerofill __DATA,__bss,_vals,8000000,2 ## @vals
+ at vals = internal unnamed_addr global [2000000 x i32] undef, align 4
+
+; CHECK: .zerofill __DATA,__bss,_struct,8000040,3 ## @struct
+ at struct = internal global { i1, [8000000 x i8], [7 x i8], i64, { [4 x i32], { i8 }, i1 } }
+                { i1 false, [8000000 x i8] zeroinitializer, [7 x i8] undef, i64 0,
+                        { [4 x i32], { i8 }, i1 }
+                        { [4 x i32] zeroinitializer, { i8 } { i8 undef }, i1 false }
+                }, align 8
Index: llvm/trunk/test/CodeGen/ARM/memfunc.ll
===================================================================
--- llvm/trunk/test/CodeGen/ARM/memfunc.ll
+++ llvm/trunk/test/CodeGen/ARM/memfunc.ll
@@ -421,8 +421,10 @@
 ; CHECK: arr5:
 ; CHECK-NOT: .p2align
 ; CHECK: arr6:
-; CHECK: .p2align 4
-; CHECK: arr8:
+; CHECK-IOS: arr8,128,4
+; CHECK-DARWIN: arr8,128,4
+; CHECK-EABI: arr8,128,16
+; CHECK-GNUEABI: arr8,128,16
 ; CHECK: .p2align 4
 ; CHECK: arr9:
 


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