WinCOFF: Add support for -fdata-sections

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

N.B. We must be careful to avoid sticking entities with private linkage
in COMDAT groups.  COFF is pretty hostile to the renaming of entities so
we must be careful to disallow GlobalVariables with unstable names.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204703 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 8f113d791625ce0e2f1a0ab4512f18b8804a637e..e41fbfc6d360e06fb4b242c59a0468ca1d3203d8 100644 (file)
--- a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -770,12 +770,18 @@ 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();
+  bool EmitUniquedSection;
+  if (Kind.isText())
+    EmitUniquedSection = TM.getFunctionSections();
+  else
+    EmitUniquedSection = TM.getDataSections();
 
   // 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() || EmitUniquedSection) {
+  // Section names depend on the name of the symbol which is not feasible if the
+  // symbol has private linkage.
+  if ((GV->isWeakForLinker() || EmitUniquedSection) &&
+      !GV->hasPrivateLinkage()) {
     const char *Name = getCOFFSectionNameForUniqueGlobal(Kind);
     unsigned Characteristics = getCOFFSectionFlags(Kind);
 

diff --git a/test/CodeGen/X86/global-sections.ll b/test/CodeGen/X86/global-sections.ll
index c768c303c8726bb0112c396b95ce7a7a95f08591..5ad504719fcd35f2d157f73bf54ebe69d87397ab 100644 (file)
--- a/test/CodeGen/X86/global-sections.ll
+++ b/test/CodeGen/X86/global-sections.ll
@@ -3,8 +3,14 @@
 ; 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
+; RUN: llc < %s -mtriple=i686-pc-win32 -fdata-sections -ffunction-sections | FileCheck %s -check-prefix=WIN32-SECTIONS
 
+define void @F1() {
+  ret void
+}
+
+; WIN32-SECTIONS: .section        .text,"xr",one_only,_F1
+; WIN32-SECTIONS: .globl _F1
 
 ; int G1;
 @G1 = common global i32 0
@@ -42,6 +48,9 @@
 ; LINUX-SECTIONS: .section        .rodata.G3,"a",@progbits
 ; LINUX-SECTIONS: .globl  G3
 
+; WIN32-SECTIONS: .section        .rdata,"r",one_only,_G3
+; WIN32-SECTIONS: .globl  _G3
+
 
 ; _Complex long long const G4 = 34;
 @G4 = unnamed_addr constant {i64,i64} { i64 34, i64 0 }
@@ -118,6 +127,9 @@
 ; LINUX-SECTIONS: .section        .rodata.G7,"aMS",@progbits,1
 ; LINUX-SECTIONS:      .globl G7
 
+; WIN32-SECTIONS: .section        .rdata,"r",one_only,_G7
+; WIN32-SECTIONS:      .globl _G7
+
 
 @G8 = unnamed_addr constant [4 x i16] [ i16 1, i16 2, i16 3, i16 0 ]
 
@@ -178,9 +190,7 @@
 ; LINUX-SECTIONS:        .asciz  "foo"
 ; LINUX-SECTIONS:        .size   .LG14, 4
 
-define void @G15() {
-  ret void
-}
+; WIN32-SECTIONS:        .section        .rdata,"r"
+; WIN32-SECTIONS: L_G14:
+; WIN32-SECTIONS:        .asciz  "foo"
 
-; WIN32-SECTIONS: .section        .text,"xr",one_only,_G15
-; WIN32-SECTIONS: .globl _G15