Pass code-model through Module IR to LTO which will use it.

Currently the code-model does not get saved in the module IR,
so if a code model is specified when compiling with LTO,
it gets lost and is not propagated properly to LTO. This patch,
along with one for the front end, fixes that.

Differential Revision: https://reviews.llvm.org/D52322

llvm-svn: 342760

include/llvm/IR/Module.h

@@ -16,6 +16,7 @@
 #define LLVM_IR_MODULE_H
 
 #include "llvm-c/Types.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
@@ -840,6 +841,17 @@ public:
   void setPIELevel(PIELevel::Level PL);
 /// @}
 
+  /// @}
+  /// @name Utility function for querying and setting code model
+  /// @{
+
+  /// Returns the code model (tiny, small, kernel, medium or large model)
+  Optional<CodeModel::Model> getCodeModel() const;
+
+  /// Set the code model (tiny, small, kernel, medium or large)
+  void setCodeModel(CodeModel::Model CL);
+  /// @}
+
   /// @name Utility functions for querying and setting PGO summary
   /// @{
 

lib/IR/Module.cpp

@@ -13,6 +13,7 @@
 
 #include "llvm/IR/Module.h"
 #include "SymbolTableListTraitsImpl.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
@@ -507,6 +508,24 @@ void Module::setPIELevel(PIELevel::Level PL) {
   addModuleFlag(ModFlagBehavior::Max, "PIE Level", PL);
 }
 
+Optional<CodeModel::Model> Module::getCodeModel() const {
+  auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("Code Model"));
+
+  if (!Val)
+    return None;
+
+  return static_cast<CodeModel::Model>(
+      cast<ConstantInt>(Val->getValue())->getZExtValue());
+}
+
+void Module::setCodeModel(CodeModel::Model CL) {
+  // Linking object files with different code models is undefined behavior
+  // because the compiler would have to generate additional code (to span
+  // longer jumps) if a larger code model is used with a smaller one.
+  // Therefore we will treat attempts to mix code models as an error.
+  addModuleFlag(ModFlagBehavior::Error, "Code Model", CL);
+}
+
 void Module::setProfileSummary(Metadata *M) {
   addModuleFlag(ModFlagBehavior::Error, "ProfileSummary", M);
 }

lib/LTO/LTOBackend.cpp

@@ -138,9 +138,15 @@ createTargetMachine(Config &Conf, const Target *TheTarget, Module &M) {
     RelocModel =
         M.getPICLevel() == PICLevel::NotPIC ? Reloc::Static : Reloc::PIC_;
 
+  Optional<CodeModel::Model> CodeModel;
+  if (Conf.CodeModel)
+    CodeModel = *Conf.CodeModel;
+  else
+    CodeModel = M.getCodeModel();
+
   return std::unique_ptr<TargetMachine>(TheTarget->createTargetMachine(
       TheTriple, Conf.CPU, Features.getString(), Conf.Options, RelocModel,
-      Conf.CodeModel, Conf.CGOptLevel));
+      CodeModel, Conf.CGOptLevel));
 }
 
 static void runNewPMPasses(Config &Conf, Module &Mod, TargetMachine *TM,

test/LTO/X86/Inputs/codemodel-3.ll

@@ -0,0 +1,16 @@
+target triple = "x86_64-unknown-linux-gnu"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"Code Model", i32 1}
+
+%struct.rtx_def = type { i16, i16 }
+
+define void @bar(%struct.rtx_def* %a, i8 %b, i32 %c) {
+  call void  @llvm.memset.p0struct.rtx_def.i32(%struct.rtx_def* align 4 %a, i8 %b, i32 %c, i1 true)
+  ret void
+}
+
+declare void @llvm.memset.p0struct.rtx_def.i32(%struct.rtx_def*, i8, i32, i1)

test/LTO/X86/codemodel-1.ll

@@ -0,0 +1,20 @@
+; RUN: llvm-as %s -o %t.o
+; RUN: llvm-lto2 run -r %t.o,_start,px %t.o -o %t.s
+; RUN: llvm-objdump -d %t.s.0 | FileCheck %s --check-prefix=CHECK-SMALL
+
+target triple = "x86_64-unknown-linux-gnu"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"Code Model", i32 1}
+
+@data = internal constant [0 x i32] []
+
+define i32* @_start() nounwind readonly {
+entry:
+; CHECK-SMALL-LABEL:  _start:
+; CHECK-SMALL: leaq    (%rip), %rax
+    ret i32* getelementptr ([0 x i32], [0 x i32]* @data, i64 0, i64 0)
+}

test/LTO/X86/codemodel-2.ll

@@ -0,0 +1,20 @@
+; RUN: llvm-as %s -o %t.o
+; RUN: llvm-lto2 run -r %t.o,_start,px %t.o -o %t.s
+; RUN: llvm-objdump -d %t.s.0 | FileCheck %s --check-prefix=CHECK-LARGE
+
+target triple = "x86_64-unknown-linux-gnu"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"Code Model", i32 4}
+
+@data = internal constant [0 x i32] []
+
+define i32* @_start() nounwind readonly {
+entry:
+; CHECK-LARGE-LABEL: _start:
+; CHECK-LARGE: movabsq $0, %rax
+    ret i32* getelementptr ([0 x i32], [0 x i32]* @data, i64 0, i64 0)
+}

test/LTO/X86/codemodel-3.ll

@@ -0,0 +1,20 @@
+; RUN: llvm-as %s -o %t0.o
+; RUN: llvm-as < %p/Inputs/codemodel-3.ll > %t1.o
+; RUN: not llvm-lto2 run -r %t0.o,_start,px -r %t1.o,bar,px %t0.o %t1.o -o %t2.s 2>&1 | FileCheck %s 
+
+target triple = "x86_64-unknown-linux-gnu"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"Code Model", i32 4}
+
+@data = internal constant [0 x i32] []
+
+define i32* @_start() nounwind readonly {
+entry:
+    ret i32* getelementptr ([0 x i32], [0 x i32]* @data, i64 0, i64 0)
+}
+
+; CHECK: 'Code Model': IDs have conflicting values