[PATCH] D65478: Create unique, but identically-named ELF sections for explicitly-sectioned functions when using -function-sections.

[Rahman Lavaee via Phabricator via llvm-commits]

rahmanl created this revision.
rahmanl added reviewers: eugenis, tmsriram.
rahmanl added a project: LLVM.
Herald added a subscriber: llvm-commits.

This allows functions to to be reordered later in the linking phase (using the -symbol-ordering-file) even though reordering will be limited to the scope of the explicit section.


Repository:
  rL LLVM

https://reviews.llvm.org/D65478

Files:
  lib/CodeGen/TargetLoweringObjectFileImpl.cpp
  test/CodeGen/X86/explicit-function-sections.ll


Index: test/CodeGen/X86/explicit-function-sections.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/explicit-function-sections.ll
@@ -0,0 +1,24 @@
+; RUN: llc < %s -mtriple=x86_64-pc-linux -function-sections | FileCheck %s -check-prefix=FSECTIONS
+; RUN: llc < %s -mtriple=x86_64-pc-linux | FileCheck %s -check-prefix=NOFSECTIONS
+
+define void @f() section "special_section" {
+  ret void
+}
+define void @g() section "special_section" {
+  ret void
+}
+
+; NOFSECTIONS:		.section	special_section,"ax", at progbits
+; NOFSECTIONS-NOT: 	section
+; NOFSECTIONS:		f:
+; NOFSECTIONS-NOT: 	section
+; NOFSECTIONS:		g:
+
+; FSECTIONS:		.section	special_section,"ax", at progbits
+; FSECTIONS-NOT: 	section
+; FSECTIONS:		f:
+; FSECTIONS:		.section	special_section,"ax", at progbits
+; FSECTIONS-NOT: 	section
+; FSECTIONS:		g:
+
+
Index: lib/CodeGen/TargetLoweringObjectFileImpl.cpp
===================================================================
--- lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -593,6 +593,10 @@
   if (AssociatedSymbol) {
     UniqueID = NextUniqueID++;
     Flags |= ELF::SHF_LINK_ORDER;
+  } else if(F && TM.getFunctionSections()){
+    // Also, if -ffunction-sections is used and the global is a function, then
+    // emit a unique section.
+    UniqueID = NextUniqueID++;
   }
 
   MCSectionELF *Section = getContext().getELFSection(


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