From 8048ebe91d76f5ee58f5c2c7535151d782af4b29 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Mon, 27 Sep 2010 06:44:54 +0000
Subject: [PATCH] the latest assembler that runs on powerpc 10.4 machines
 doesn't support aligned comm.  Detect when compiling for 10.4 and don't emit
 an alignment for comm.  THis will hopefully fix PR8198.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114817 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Target/TargetLoweringObjectFile.h |  9 +++++++++
 include/llvm/Target/TargetMachine.h            |  2 ++
 lib/CodeGen/AsmPrinter/AsmPrinter.cpp          | 12 ++++++++++--
 lib/CodeGen/TargetLoweringObjectFileImpl.cpp   | 14 ++++++++++++++
 lib/Target/TargetLoweringObjectFile.cpp        |  1 +
 test/CodeGen/PowerPC/align.ll                  |  4 ++++
 6 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/include/llvm/Target/TargetLoweringObjectFile.h b/include/llvm/Target/TargetLoweringObjectFile.h
index 819709fa20c..5456dd07003 100644
--- a/include/llvm/Target/TargetLoweringObjectFile.h
+++ b/include/llvm/Target/TargetLoweringObjectFile.h
@@ -92,6 +92,11 @@ protected:
   // information for a TLS variable, it'll go here.
   const MCSection *TLSExtraDataSection;
   
+  /// CommDirectiveSupportsAlignment - True if .comm supports alignment.  This
+  /// is a hack for as long as we support 10.4 Tiger, whose assembler doesn't
+  /// support alignment on comm.
+  bool CommDirectiveSupportsAlignment;
+  
   /// SupportsWeakEmptyEHFrame - True if target object file supports a
   /// weak_definition of constant 0 for an omitted EH frame.
   bool SupportsWeakOmittedEHFrame;
@@ -128,6 +133,10 @@ public:
     return SupportsWeakOmittedEHFrame;
   }
   
+  bool getCommDirectiveSupportsAlignment() const {
+    return CommDirectiveSupportsAlignment;
+  }
+
   const MCSection *getTextSection() const { return TextSection; }
   const MCSection *getDataSection() const { return DataSection; }
   const MCSection *getBSSSection() const { return BSSSection; }
diff --git a/include/llvm/Target/TargetMachine.h b/include/llvm/Target/TargetMachine.h
index 426338ff8d4..35f2658acd9 100644
--- a/include/llvm/Target/TargetMachine.h
+++ b/include/llvm/Target/TargetMachine.h
@@ -280,6 +280,8 @@ private:
   
 public:
   
+  const std::string &getTargetTriple() const { return TargetTriple; }
+  
   /// addPassesToEmitFile - Add passes to the specified pass manager to get the
   /// specified file emitted.  Typically this will involve several steps of code
   /// generation.  If OptLevel is None, the code generator should emit code as
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index ee6d321763a..0de20211336 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -282,8 +282,12 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
     
     // Handle common symbols.
     if (GVKind.isCommon()) {
+      unsigned Align = 1 << AlignLog;
+      if (!getObjFileLowering().getCommDirectiveSupportsAlignment())
+        Align = 0;
+          
       // .comm _foo, 42, 4
-      OutStreamer.EmitCommonSymbol(GVSym, Size, 1 << AlignLog);
+      OutStreamer.EmitCommonSymbol(GVSym, Size, Align);
       return;
     }
     
@@ -301,11 +305,15 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
       OutStreamer.EmitLocalCommonSymbol(GVSym, Size);
       return;
     }
+
+    unsigned Align = 1 << AlignLog;
+    if (!getObjFileLowering().getCommDirectiveSupportsAlignment())
+      Align = 0;
     
     // .local _foo
     OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Local);
     // .comm _foo, 42, 4
-    OutStreamer.EmitCommonSymbol(GVSym, Size, 1 << AlignLog);
+    OutStreamer.EmitCommonSymbol(GVSym, Size, Align);
     return;
   }
   
diff --git a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index f1e10eec724..4afdc3ddef5 100644
--- a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/Triple.h"
 using namespace llvm;
 using namespace dwarf;
 
@@ -450,6 +451,19 @@ void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
   IsFunctionEHSymbolGlobal = true;
   IsFunctionEHFrameSymbolPrivate = false;
   SupportsWeakOmittedEHFrame = false;
+
+  Triple T(((LLVMTargetMachine&)TM).getTargetTriple());
+  if (T.getOS() == Triple::Darwin) {
+    switch (T.getDarwinMajorNumber()) {
+    case 7:  // 10.3 Panther.
+    case 8:  // 10.4 Tiger.
+      CommDirectiveSupportsAlignment = false;
+      break;
+    case 9:   // 10.5 Leopard.
+    case 10:  // 10.6 SnowLeopard.
+      break;
+    }
+  }
   
   TargetLoweringObjectFile::Initialize(Ctx, TM);
 
diff --git a/lib/Target/TargetLoweringObjectFile.cpp b/lib/Target/TargetLoweringObjectFile.cpp
index dd7b532bbfb..0e67fe5d987 100644
--- a/lib/Target/TargetLoweringObjectFile.cpp
+++ b/lib/Target/TargetLoweringObjectFile.cpp
@@ -45,6 +45,7 @@ TargetLoweringObjectFile::TargetLoweringObjectFile() : Ctx(0) {
   LSDASection = 0;
   EHFrameSection = 0;
 
+  CommDirectiveSupportsAlignment = true;
   DwarfAbbrevSection = 0;
   DwarfInfoSection = 0;
   DwarfLineSection = 0;
diff --git a/test/CodeGen/PowerPC/align.ll b/test/CodeGen/PowerPC/align.ll
index 109a83726e9..0797ca8d0be 100644
--- a/test/CodeGen/PowerPC/align.ll
+++ b/test/CodeGen/PowerPC/align.ll
@@ -1,5 +1,6 @@
 ; RUN: llc < %s -mtriple=powerpc-linux-gnu | FileCheck %s -check-prefix=ELF
 ; RUN: llc < %s -mtriple=powerpc-apple-darwin9 | FileCheck %s -check-prefix=DARWIN
+; RUN: llc < %s -mtriple=powerpc-apple-darwin8 | FileCheck %s -check-prefix=DARWIN8
 
 @a = global i1 true
 ; no alignment
@@ -40,3 +41,6 @@
 @bar = common global [75 x i8] zeroinitializer, align 128
 ;ELF: .comm bar,75,128
 ;DARWIN: .comm _bar,75,7
+
+;; Darwin8 doesn't support aligned comm.  Just miscompile this.
+; DARWIN8: .comm _bar,75 ;