WinCOFF: Add support for -ffunction-sections

This is a pretty straight forward translation for COFF, we just need to
stick the function in a COMDAT section marked as
IMAGE_COMDAT_SELECT_NODUPLICATES.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204565 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index a2f4810cb6c75aeebb0045d74c182ef7404b459f..8f113d791625ce0e2f1a0ab4512f18b8804a637e 100644 (file)
--- a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -768,18 +768,23 @@ static const char *getCOFFSectionNameForUniqueGlobal(SectionKind Kind) {
 const MCSection *TargetLoweringObjectFileCOFF::
 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
                        Mangler &Mang, const TargetMachine &TM) const {
+  // If we have -ffunction-sections then we should emit the global value to a
+  // uniqued section specifically for it.
+  // TODO: Implement -fdata-sections.
+  bool EmitUniquedSection = Kind.isText() && TM.getFunctionSections();
 
   // If this global is linkonce/weak and the target handles this by emitting it
   // into a 'uniqued' section name, create and return the section now.
-  if (GV->isWeakForLinker()) {
+  if (GV->isWeakForLinker() || EmitUniquedSection) {
     const char *Name = getCOFFSectionNameForUniqueGlobal(Kind);
     unsigned Characteristics = getCOFFSectionFlags(Kind);
 
     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
     MCSymbol *Sym = TM.getSymbol(GV, Mang);
-    return getContext().getCOFFSection(Name, Characteristics,
-                                       Kind, Sym->getName(),
-                                       COFF::IMAGE_COMDAT_SELECT_ANY);
+    return getContext().getCOFFSection(
+        Name, Characteristics, Kind, Sym->getName(),
+        GV->isWeakForLinker() ? COFF::IMAGE_COMDAT_SELECT_ANY
+                              : COFF::IMAGE_COMDAT_SELECT_NODUPLICATES);
   }
 
   if (Kind.isText())

diff --git a/test/CodeGen/X86/global-sections.ll b/test/CodeGen/X86/global-sections.ll
index c031821f9a6e3b268df8cc9271924eb289eb016b..c768c303c8726bb0112c396b95ce7a7a95f08591 100644 (file)
--- a/test/CodeGen/X86/global-sections.ll
+++ b/test/CodeGen/X86/global-sections.ll
@@ -3,6 +3,7 @@
 ; RUN: llc < %s -mtriple=i386-apple-darwin10 -relocation-model=static | FileCheck %s -check-prefix=DARWIN-STATIC
 ; RUN: llc < %s -mtriple=x86_64-apple-darwin10 | FileCheck %s -check-prefix=DARWIN64
 ; RUN: llc < %s -mtriple=i386-unknown-linux-gnu -fdata-sections | FileCheck %s -check-prefix=LINUX-SECTIONS
+; RUN: llc < %s -mtriple=i686-pc-win32 -ffunction-sections | FileCheck %s -check-prefix=WIN32-SECTIONS
 
 
 ; int G1;
@@ -176,3 +177,10 @@
 ; LINUX-SECTIONS: .LG14:
 ; LINUX-SECTIONS:        .asciz  "foo"
 ; LINUX-SECTIONS:        .size   .LG14, 4
+
+define void @G15() {
+  ret void
+}
+
+; WIN32-SECTIONS: .section        .text,"xr",one_only,_G15
+; WIN32-SECTIONS: .globl _G15