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

7 files changed, 114 insertions, 1 deletions

diff --git a/llvm/include/llvm/IR/Module.h b/llvm/include/llvm/IR/Module.h
index a405f7df3ef..91e44addbd6 100644
--- a/llvm/include/llvm/IR/Module.h
+++ b/llvm/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
   /// @{
 
diff --git a/llvm/lib/IR/Module.cpp b/llvm/lib/IR/Module.cpp
index 882ab106a37..7d02a3956ff 100644
--- a/llvm/lib/IR/Module.cpp
+++ b/llvm/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);
 }
diff --git a/llvm/lib/LTO/LTOBackend.cpp b/llvm/lib/LTO/LTOBackend.cpp
index eadbb410bd5..be33ab84933 100644
--- a/llvm/lib/LTO/LTOBackend.cpp
+++ b/llvm/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,
diff --git a/llvm/test/LTO/X86/Inputs/codemodel-3.ll b/llvm/test/LTO/X86/Inputs/codemodel-3.ll
new file mode 100644
index 00000000000..7b264af6f48
--- /dev/null
+++ b/llvm/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)
diff --git a/llvm/test/LTO/X86/codemodel-1.ll b/llvm/test/LTO/X86/codemodel-1.ll
new file mode 100644
index 00000000000..ca89c943376
--- /dev/null
+++ b/llvm/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)
+}
diff --git a/llvm/test/LTO/X86/codemodel-2.ll b/llvm/test/LTO/X86/codemodel-2.ll
new file mode 100644
index 00000000000..408c02a9ecf
--- /dev/null
+++ b/llvm/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)
+}
diff --git a/llvm/test/LTO/X86/codemodel-3.ll b/llvm/test/LTO/X86/codemodel-3.ll
new file mode 100644
index 00000000000..987d37d22c1
--- /dev/null
+++ b/llvm/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