Compare DataLayout by Value, not by pointer.

This fixes spurious warnings in llvm-link about the datalayout not matching.

Thanks to Zalman Stern for reporting the bug!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202276 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/DataLayout.h

@@ -193,6 +193,9 @@ class DataLayout {
     return *this;
   }
 
+  bool operator==(const DataLayout &Other) const;
+  bool operator!=(const DataLayout &Other) const { return !(*this == Other); }
+
   ~DataLayout();  // Not virtual, do not subclass this class
 
   /// Parse a data layout string (with fallback to default values).

lib/IR/DataLayout.cpp

@@ -354,6 +354,16 @@ DataLayout::DataLayout(const Module *M) : LayoutMap(0) {
     reset("");
 }
 
+bool DataLayout::operator==(const DataLayout &Other) const {
+  bool Ret = LittleEndian == Other.LittleEndian &&
+             StackNaturalAlign == Other.StackNaturalAlign &&
+             ManglingMode == Other.ManglingMode &&
+             LegalIntWidths == Other.LegalIntWidths &&
+             Alignments == Other.Alignments && Pointers == Pointers;
+  assert(Ret == (getStringRepresentation() == Other.getStringRepresentation()));
+  return Ret;
+}
+
 void
 DataLayout::setAlignment(AlignTypeEnum align_type, unsigned abi_align,
                          unsigned pref_align, uint32_t bit_width) {

lib/Linker/LinkModules.cpp

@@ -1208,7 +1208,7 @@ bool ModuleLinker::run() {
     DstM->setTargetTriple(SrcM->getTargetTriple());
 
   if (SrcM->getDataLayout() && DstM->getDataLayout() &&
-      SrcM->getDataLayout() != DstM->getDataLayout()) {
+      *SrcM->getDataLayout() != *DstM->getDataLayout()) {
     if (!SuppressWarnings) {
       errs() << "WARNING: Linking two modules of different data layouts!\n";
     }

test/Linker/Inputs/datalayout-a.ll

@@ -0,0 +1 @@
+target datalayout = "e"

test/Linker/Inputs/datalayout-b.ll

@@ -0,0 +1 @@
+target datalayout = "E"

test/Linker/datalayout.ll

@@ -0,0 +1,14 @@
+; RUN: llvm-link %s %S/Inputs/datalayout-a.ll -S -o - 2>%t.a.err | FileCheck %s
+; RUN: cat %t.a.err | not FileCheck %s 2>&1 | FileCheck --check-prefix=WARN-A %s
+
+; RUN: llvm-link %s %S/Inputs/datalayout-b.ll -S -o - 2>%t.b.err | FileCheck %s
+; RUN: cat %t.b.err | FileCheck --check-prefix=WARN-B %s
+
+target datalayout = "e"
+
+; CHECK: target datalayout = "e"
+
+; this is a hack to check that llvm-link printed no warnings.
+; WARN-A: FileCheck error: '-' is empty.
+
+; WARN-B: WARNING: Linking two modules of different data layouts!