Rollback of rL355585.

Introduces memory leak in FunctionTest.GetPointerAlignment that breaks sanitizer buildbots:

```
=================================================================
==2453==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 128 byte(s) in 1 object(s) allocated from:
    #0 0x610428 in operator new(unsigned long) /b/sanitizer-x86_64-linux-bootstrap/build/llvm/projects/compiler-rt/lib/asan/asan_new_delete.cc:105
    #1 0x16936bc in llvm::User::operator new(unsigned long) /b/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/IR/User.cpp:151:19
    #2 0x7c3fe9 in Create /b/sanitizer-x86_64-linux-bootstrap/build/llvm/include/llvm/IR/Function.h:144:12
    #3 0x7c3fe9 in (anonymous namespace)::FunctionTest_GetPointerAlignment_Test::TestBody() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/unittests/IR/FunctionTest.cpp:136
    #4 0x1a836a0 in HandleExceptionsInMethodIfSupported<testing::Test, void> /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc
    #5 0x1a836a0 in testing::Test::Run() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc:2474
    #6 0x1a85c55 in testing::TestInfo::Run() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc:2656:11
    #7 0x1a870d0 in testing::TestCase::Run() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc:2774:28
    #8 0x1aa5b84 in testing::internal::UnitTestImpl::RunAllTests() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc:4649:43
    #9 0x1aa4d30 in HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool> /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc
    #10 0x1aa4d30 in testing::UnitTest::Run() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc:4257
    #11 0x1a6b656 in RUN_ALL_TESTS /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/include/gtest/gtest.h:2233:46
    #12 0x1a6b656 in main /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/UnitTestMain/TestMain.cpp:50
    #13 0x7f5af37a22e0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202e0)

Indirect leak of 40 byte(s) in 1 object(s) allocated from:
    #0 0x610428 in operator new(unsigned long) /b/sanitizer-x86_64-linux-bootstrap/build/llvm/projects/compiler-rt/lib/asan/asan_new_delete.cc:105
    #1 0x151be6b in make_unique<llvm::ValueSymbolTable> /b/sanitizer-x86_64-linux-bootstrap/build/llvm/include/llvm/ADT/STLExtras.h:1349:29
    #2 0x151be6b in llvm::Function::Function(llvm::FunctionType*, llvm::GlobalValue::LinkageTypes, unsigned int, llvm::Twine const&, llvm::Module*) /b/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/IR/Function.cpp:241
    #3 0x7c4006 in Create /b/sanitizer-x86_64-linux-bootstrap/build/llvm/include/llvm/IR/Function.h:144:16
    #4 0x7c4006 in (anonymous namespace)::FunctionTest_GetPointerAlignment_Test::TestBody() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/unittests/IR/FunctionTest.cpp:136
    #5 0x1a836a0 in HandleExceptionsInMethodIfSupported<testing::Test, void> /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc
    #6 0x1a836a0 in testing::Test::Run() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc:2474
    #7 0x1a85c55 in testing::TestInfo::Run() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc:2656:11
    #8 0x1a870d0 in testing::TestCase::Run() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc:2774:28
    #9 0x1aa5b84 in testing::internal::UnitTestImpl::RunAllTests() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc:4649:43
    #10 0x1aa4d30 in HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool> /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc
    #11 0x1aa4d30 in testing::UnitTest::Run() /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/src/gtest.cc:4257
    #12 0x1a6b656 in RUN_ALL_TESTS /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/googletest/include/gtest/gtest.h:2233:46
    #13 0x1a6b656 in main /b/sanitizer-x86_64-linux-bootstrap/build/llvm/utils/unittest/UnitTestMain/TestMain.cpp:50
    #14 0x7f5af37a22e0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202e0)

SUMMARY: AddressSanitizer: 168 byte(s) leaked in 2 allocation(s).
```

See http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/11358/steps/check-llvm%20asan/logs/stdio for more information.

Also introduces use-of-uninitialized-value in ConstantsTest.FoldGlobalVariablePtr:
```
==7070==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x14e703c in User /b/sanitizer-x86_64-linux-fast/build/llvm/include/llvm/IR/User.h:79:5
    #1 0x14e703c in Constant /b/sanitizer-x86_64-linux-fast/build/llvm/include/llvm/IR/Constant.h:44
    #2 0x14e703c in llvm::GlobalValue::GlobalValue(llvm::Type*, llvm::Value::ValueTy, llvm::Use*, unsigned int, llvm::GlobalValue::LinkageTypes, llvm::Twine const&, unsigned int) /b/sanitizer-x86_64-linux-fast/build/llvm/include/llvm/IR/GlobalValue.h:78
    #3 0x14e5467 in GlobalObject /b/sanitizer-x86_64-linux-fast/build/llvm/include/llvm/IR/GlobalObject.h:34:9
    #4 0x14e5467 in llvm::GlobalVariable::GlobalVariable(llvm::Type*, bool, llvm::GlobalValue::LinkageTypes, llvm::Constant*, llvm::Twine const&, llvm::GlobalValue::ThreadLocalMode, unsigned int, bool) /b/sanitizer-x86_64-linux-fast/build/llvm/lib/IR/Globals.cpp:314
    #5 0x6938f1 in llvm::(anonymous namespace)::ConstantsTest_FoldGlobalVariablePtr_Test::TestBody() /b/sanitizer-x86_64-linux-fast/build/llvm/unittests/IR/ConstantsTest.cpp:565:18
    #6 0x1a240a1 in HandleExceptionsInMethodIfSupported<testing::Test, void> /b/sanitizer-x86_64-linux-fast/build/llvm/utils/unittest/googletest/src/gtest.cc
    #7 0x1a240a1 in testing::Test::Run() /b/sanitizer-x86_64-linux-fast/build/llvm/utils/unittest/googletest/src/gtest.cc:2474
    #8 0x1a26d26 in testing::TestInfo::Run() /b/sanitizer-x86_64-linux-fast/build/llvm/utils/unittest/googletest/src/gtest.cc:2656:11
    #9 0x1a2815f in testing::TestCase::Run() /b/sanitizer-x86_64-linux-fast/build/llvm/utils/unittest/googletest/src/gtest.cc:2774:28
    #10 0x1a43de8 in testing::internal::UnitTestImpl::RunAllTests() /b/sanitizer-x86_64-linux-fast/build/llvm/utils/unittest/googletest/src/gtest.cc:4649:43
    #11 0x1a42c47 in HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool> /b/sanitizer-x86_64-linux-fast/build/llvm/utils/unittest/googletest/src/gtest.cc
    #12 0x1a42c47 in testing::UnitTest::Run() /b/sanitizer-x86_64-linux-fast/build/llvm/utils/unittest/googletest/src/gtest.cc:4257
    #13 0x1a0dfba in RUN_ALL_TESTS /b/sanitizer-x86_64-linux-fast/build/llvm/utils/unittest/googletest/include/gtest/gtest.h:2233:46
    #14 0x1a0dfba in main /b/sanitizer-x86_64-linux-fast/build/llvm/utils/unittest/UnitTestMain/TestMain.cpp:50
    #15 0x7f2081c412e0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202e0)
    #16 0x4dff49 in _start (/b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/unittests/IR/IRTests+0x4dff49)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /b/sanitizer-x86_64-linux-fast/build/llvm/include/llvm/IR/User.h:79:5 in User
```

See http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/30222/steps/check-llvm%20msan/logs/stdio for more information.

llvm-svn: 355616

Author: hctim

clang/lib/Basic/Targets/ARM.cpp

@@ -40,26 +40,25 @@ void ARMTargetInfo::setABIAAPCS() {
   // so set preferred for small types to 32.
   if (T.isOSBinFormatMachO()) {
     resetDataLayout(BigEndian
-                        ? "E-m:o-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
-                        : "e-m:o-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64");
+                        ? "E-m:o-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+                        : "e-m:o-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64");
   } else if (T.isOSWindows()) {
     assert(!BigEndian && "Windows on ARM does not support big endian");
     resetDataLayout("e"
                     "-m:w"
                     "-p:32:32"
-                    "-Fi8"
                     "-i64:64"
                     "-v128:64:128"
                     "-a:0:32"
                     "-n32"
                     "-S64");
   } else if (T.isOSNaCl()) {
     assert(!BigEndian && "NaCl on ARM does not support big endian");
-    resetDataLayout("e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S128");
+    resetDataLayout("e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S128");
   } else {
     resetDataLayout(BigEndian
-                        ? "E-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
-                        : "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64");
+                        ? "E-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+                        : "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64");
   }
 
   // FIXME: Enumerated types are variable width in straight AAPCS.
@@ -88,17 +87,17 @@ void ARMTargetInfo::setABIAPCS(bool IsAAPCS16) {
 
   if (T.isOSBinFormatMachO() && IsAAPCS16) {
     assert(!BigEndian && "AAPCS16 does not support big-endian");
-    resetDataLayout("e-m:o-p:32:32-Fi8-i64:64-a:0:32-n32-S128");
+    resetDataLayout("e-m:o-p:32:32-i64:64-a:0:32-n32-S128");
   } else if (T.isOSBinFormatMachO())
     resetDataLayout(
         BigEndian
-            ? "E-m:o-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
-            : "e-m:o-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32");
+            ? "E-m:o-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
+            : "e-m:o-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32");
   else
     resetDataLayout(
         BigEndian
-            ? "E-m:e-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
-            : "e-m:e-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32");
+            ? "E-m:e-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
+            : "e-m:e-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32");
 
   // FIXME: Override "preferred align" for double and long long.
 }
@@ -1056,7 +1055,7 @@ CygwinARMTargetInfo::CygwinARMTargetInfo(const llvm::Triple &Triple,
   this->WCharType = TargetInfo::UnsignedShort;
   TLSSupported = false;
   DoubleAlign = LongLongAlign = 64;
-  resetDataLayout("e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64");
+  resetDataLayout("e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64");
 }
 
 void CygwinARMTargetInfo::getTargetDefines(const LangOptions &Opts,

clang/test/CodeGen/armv7k-abi.c

@@ -4,7 +4,7 @@
 
 // Make sure 64 and 128 bit types are naturally aligned by the v7k ABI:
 
-// CHECK: target datalayout = "e-m:o-p:32:32-Fi8-i64:64-a:0:32-n32-S128"
+// CHECK: target datalayout = "e-m:o-p:32:32-i64:64-a:0:32-n32-S128"
 
 typedef struct {
   float arr[4];

clang/test/CodeGen/target-data.c

@@ -96,7 +96,7 @@
 
 // RUN: %clang_cc1 -triple arm-nacl -o - -emit-llvm %s | \
 // RUN: FileCheck %s -check-prefix=ARM-NACL
-// ARM-NACL: target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S128"
+// ARM-NACL: target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S128"
 
 // RUN: %clang_cc1 -triple mipsel-nacl -o - -emit-llvm %s | \
 // RUN: FileCheck %s -check-prefix=MIPS-NACL
@@ -165,19 +165,19 @@
 
 // RUN: %clang_cc1 -triple thumb-unknown-gnueabi -o - -emit-llvm %s | \
 // RUN: FileCheck %s -check-prefix=THUMB
-// THUMB: target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+// THUMB: target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
 
 // RUN: %clang_cc1 -triple arm-unknown-gnueabi -o - -emit-llvm %s | \
 // RUN: FileCheck %s -check-prefix=ARM
-// ARM: target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+// ARM: target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
 
 // RUN: %clang_cc1 -triple thumb-unknown -o - -emit-llvm -target-abi apcs-gnu \
 // RUN: %s | FileCheck %s -check-prefix=THUMB-GNU
-// THUMB-GNU: target datalayout = "e-m:e-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
+// THUMB-GNU: target datalayout = "e-m:e-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
 
 // RUN: %clang_cc1 -triple arm-unknown -o - -emit-llvm -target-abi apcs-gnu \
 // RUN: %s | FileCheck %s -check-prefix=ARM-GNU
-// ARM-GNU: target datalayout = "e-m:e-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
+// ARM-GNU: target datalayout = "e-m:e-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
 
 // RUN: %clang_cc1 -triple arc-unknown-unknown -o - -emit-llvm %s | \
 // RUN: FileCheck %s -check-prefix=ARC

llvm/docs/LangRef.rst

@@ -2004,14 +2004,6 @@ as follows:
     targets.
 ``a:<abi>:<pref>``
     This specifies the alignment for an object of aggregate type.
-``F<type><abi>``
-    This specifies the alignment for function pointers.
-    The options for ``<type>`` are:
-
-    * ``i``: The alignment of function pointers is independent of the alignment
-      of functions, and is a multiple of ``<abi>``.
-    * ``n``: The alignment of function pointers is a multiple of the explicit
-      alignment specified on the function, and is a multiple of ``<abi>``.
 ``m:<mangling>``
     If present, specifies that llvm names are mangled in the output. Symbols
     prefixed with the mangling escape character ``\01`` are passed through

llvm/include/llvm/IR/DataLayout.h

@@ -108,13 +108,6 @@ struct PointerAlignElem {
 /// generating LLVM IR is required to generate the right target data for the
 /// target being codegen'd to.
 class DataLayout {
-public:
-  enum class FunctionPtrAlignType {
-    /// The function pointer alignment is independent of the function alignment.
-    Independent,
-    /// The function pointer alignment is a multiple of the function alignment.
-    MultipleOfFunctionAlign,
-  };
 private:
   /// Defaults to false.
   bool BigEndian;
@@ -123,9 +116,6 @@ class DataLayout {
   unsigned StackNaturalAlign;
   unsigned ProgramAddrSpace;
 
-  unsigned FunctionPtrAlign;
-  FunctionPtrAlignType TheFunctionPtrAlignType;
-
   enum ManglingModeT {
     MM_None,
     MM_ELF,
@@ -209,8 +199,6 @@ class DataLayout {
     BigEndian = DL.isBigEndian();
     AllocaAddrSpace = DL.AllocaAddrSpace;
     StackNaturalAlign = DL.StackNaturalAlign;
-    FunctionPtrAlign = DL.FunctionPtrAlign;
-    TheFunctionPtrAlignType = DL.TheFunctionPtrAlignType;
     ProgramAddrSpace = DL.ProgramAddrSpace;
     ManglingMode = DL.ManglingMode;
     LegalIntWidths = DL.LegalIntWidths;
@@ -268,17 +256,6 @@ class DataLayout {
   unsigned getStackAlignment() const { return StackNaturalAlign; }
   unsigned getAllocaAddrSpace() const { return AllocaAddrSpace; }
 
-  /// Returns the alignment of function pointers, which may or may not be
-  /// related to the alignment of functions.
-  /// \see getFunctionPtrAlignType
-  unsigned getFunctionPtrAlign() const { return FunctionPtrAlign; }
-
-  /// Return the type of function pointer alignment.
-  /// \see getFunctionPtrAlign
-  FunctionPtrAlignType getFunctionPtrAlignType() const {
-    return TheFunctionPtrAlignType;
-  }
-
   unsigned getProgramAddressSpace() const { return ProgramAddrSpace; }
 
   bool hasMicrosoftFastStdCallMangling() const {

llvm/lib/IR/ConstantFold.cpp

@@ -26,7 +26,6 @@
 #include "llvm/IR/GlobalAlias.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Instructions.h"
-#include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/PatternMatch.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -1077,29 +1076,10 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, Constant *C1,
             isa<GlobalValue>(CE1->getOperand(0))) {
           GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0));
 
-          unsigned GVAlign;
-
-          if (Module *TheModule = GV->getParent()) {
-            GVAlign = GV->getPointerAlignment(TheModule->getDataLayout());
-
-            // If the function alignment is not specified then assume that it
-            // is 4.
-            // This is dangerous; on x86, the alignment of the pointer
-            // corresponds to the alignment of the function, but might be less
-            // than 4 if it isn't explicitly specified.
-            // However, a fix for this behaviour was reverted because it
-            // increased code size (see https://reviews.llvm.org/D55115)
-            // FIXME: This code should be deleted once existing targets have
-            // appropriate defaults
-            if (GVAlign == 0U && isa<Function>(GV))
-              GVAlign = 4U;
-          } else if (isa<Function>(GV)) {
-            // Without a datalayout we have to assume the worst case: that the
-            // function pointer isn't aligned at all.
-            GVAlign = 0U;
-          } else {
-            GVAlign = GV->getAlignment();
-          }
+          // Functions are at least 4-byte aligned.
+          unsigned GVAlign = GV->getAlignment();
+          if (isa<Function>(GV))
+            GVAlign = std::max(GVAlign, 4U);
 
           if (GVAlign > 1) {
             unsigned DstWidth = CI2->getType()->getBitWidth();

llvm/lib/IR/DataLayout.cpp

@@ -184,8 +184,6 @@ void DataLayout::reset(StringRef Desc) {
   AllocaAddrSpace = 0;
   StackNaturalAlign = 0;
   ProgramAddrSpace = 0;
-  FunctionPtrAlign = 0;
-  TheFunctionPtrAlignType = FunctionPtrAlignType::Independent;
   ManglingMode = MM_None;
   NonIntegralAddressSpaces.clear();
 
@@ -381,22 +379,6 @@ void DataLayout::parseSpecifier(StringRef Desc) {
       StackNaturalAlign = inBytes(getInt(Tok));
       break;
     }
-    case 'F': {
-      switch (Tok.front()) {
-      case 'i':
-        TheFunctionPtrAlignType = FunctionPtrAlignType::Independent;
-        break;
-      case 'n':
-        TheFunctionPtrAlignType = FunctionPtrAlignType::MultipleOfFunctionAlign;
-        break;
-      default:
-        report_fatal_error("Unknown function pointer alignment type in "
-                           "datalayout string");
-      }
-      Tok = Tok.substr(1);
-      FunctionPtrAlign = inBytes(getInt(Tok));
-      break;
-    }
     case 'P': { // Function address space.
       ProgramAddrSpace = getAddrSpace(Tok);
       break;
@@ -450,8 +432,6 @@ bool DataLayout::operator==(const DataLayout &Other) const {
              AllocaAddrSpace == Other.AllocaAddrSpace &&
              StackNaturalAlign == Other.StackNaturalAlign &&
              ProgramAddrSpace == Other.ProgramAddrSpace &&
-             FunctionPtrAlign == Other.FunctionPtrAlign &&
-             TheFunctionPtrAlignType == Other.TheFunctionPtrAlignType &&
              ManglingMode == Other.ManglingMode &&
              LegalIntWidths == Other.LegalIntWidths &&
              Alignments == Other.Alignments && Pointers == Other.Pointers;

llvm/lib/IR/Value.cpp

@@ -648,14 +648,10 @@ unsigned Value::getPointerAlignment(const DataLayout &DL) const {
 
   unsigned Align = 0;
   if (auto *GO = dyn_cast<GlobalObject>(this)) {
-    if (isa<Function>(GO)) {
-      switch (DL.getFunctionPtrAlignType()) {
-      case DataLayout::FunctionPtrAlignType::Independent:
-        return DL.getFunctionPtrAlign();
-      case DataLayout::FunctionPtrAlignType::MultipleOfFunctionAlign:
-        return std::max(DL.getFunctionPtrAlign(), GO->getAlignment());
-      }
-    }
+    // Don't make any assumptions about function pointer alignment. Some
+    // targets use the LSBs to store additional information.
+    if (isa<Function>(GO))
+      return 0;
     Align = GO->getAlignment();
     if (Align == 0) {
       if (auto *GVar = dyn_cast<GlobalVariable>(GO)) {

llvm/lib/Target/ARM/ARMTargetMachine.cpp

@@ -141,10 +141,6 @@ static std::string computeDataLayout(const Triple &TT, StringRef CPU,
   // Pointers are 32 bits and aligned to 32 bits.
   Ret += "-p:32:32";
 
-  // Function pointers are aligned to 8 bits (because the LSB stores the
-  // ARM/Thumb state).
-  Ret += "-Fi8";
-
   // ABIs other than APCS have 64 bit integers with natural alignment.
   if (ABI != ARMBaseTargetMachine::ARM_ABI_APCS)
     Ret += "-i64:64";

llvm/unittests/IR/CMakeLists.txt

@@ -13,7 +13,6 @@ add_llvm_unittest(IRTests
   CFGBuilder.cpp
   ConstantRangeTest.cpp
   ConstantsTest.cpp
-  DataLayoutTest.cpp
   DebugInfoTest.cpp
   DebugTypeODRUniquingTest.cpp
   DominatorTreeTest.cpp