Handle ffunction-sections w/ filetype=obj.

src/IceELFObjectWriter.cpp

@@ -218,9 +218,11 @@ void ELFObjectWriter::writeFunctionCode(const IceString &FuncName,
   assert(!SectionNumbersAssigned);
   ELFTextSection *Section = nullptr;
   ELFRelocationSection *RelSection = nullptr;
-  if (TextSections.empty()) {
-    // TODO(jvoung): handle ffunction-sections.
+  const bool FunctionSections = Ctx.getFlags().getFunctionSections();
+  if (TextSections.empty() || FunctionSections) {
     IceString SectionName = ".text";
+    if (FunctionSections)
+      SectionName += "." + FuncName;
     bool IsELF64 = isELF64(Ctx.getTargetArch());
     const Elf64_Xword ShFlags = SHF_ALLOC | SHF_EXECINSTR;
     // TODO(jvoung): Should be bundle size. Grab it from that target?
@@ -254,9 +256,8 @@ void ELFObjectWriter::writeFunctionCode(const IceString &FuncName,
                            OffsetInSection, SymbolSize);
   StrTab->add(FuncName);
 
-  // Create a relocation section for the text section if needed, and copy the
-  // fixup information from per-function Assembler memory to the object
-  // writer's memory, for writing later.
+  // Copy the fixup information from per-function Assembler memory to the
+  // object writer's memory, for writing later.
   if (!Asm->fixups().empty()) {
     RelSection->addRelocations(OffsetInSection, Asm->fixups());
   }

tests_lit/llvm2ice_tests/elf_function_sections.ll

+; Tests filetype=obj with -ffunction-sections.
+
+; RUN: %p2i -i %s --args -O2 --verbose none -filetype=obj -o %t \
+; RUN:     -ffunction-sections && \
+; RUN:   llvm-readobj -file-headers -sections -section-data \
+; RUN:     -relocations -symbols %t | FileCheck %s
+
+; RUN: %p2i -i %s --args -O2 --verbose none -ffunction-sections \
+; RUN:   | llvm-mc -triple=i686-none-nacl -filetype=obj -o - \
+; RUN:   | llvm-readobj -file-headers -sections -section-data \
+; RUN:       -relocations -symbols - | FileCheck %s
+
+declare void @llvm.memcpy.p0i8.p0i8.i32(i8*, i8*, i32, i32, i1)
+
+define internal i32 @foo(i32 %x, i32 %len) {
+  %y = add i32 %x, %x
+  %dst = inttoptr i32 %y to i8*
+  %src = inttoptr i32 %x to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dst, i8* %src,
+                                       i32 %len, i32 1, i1 false)
+
+  ret i32 %y
+}
+
+define internal i32 @bar(i32 %x) {
+  ret i32 %x
+}
+
+define void @_start(i32 %x) {
+  %y = call i32 @bar(i32 4)
+  %ignored = call i32 @foo(i32 %x, i32 %y)
+  ret void
+}
+
+; CHECK:   Section {
+; CHECK:     Name: .text.foo
+; CHECK:     Type: SHT_PROGBITS
+; CHECK:     Flags [ (0x6)
+; CHECK:       SHF_ALLOC
+; CHECK:       SHF_EXECINSTR
+; CHECK:     ]
+; CHECK:   }
+; CHECK:   Section {
+; CHECK:     Name: .rel.text.foo
+; CHECK:     Type: SHT_REL
+; CHECK:     Flags [ (0x0)
+; CHECK:     ]
+; CHECK:   }
+
+; CHECK:   Section {
+; CHECK:     Name: .text.bar
+; CHECK:     Type: SHT_PROGBITS
+; CHECK:     Flags [ (0x6)
+; CHECK:       SHF_ALLOC
+; CHECK:       SHF_EXECINSTR
+; CHECK:     ]
+; CHECK:   }
+
+; CHECK:   Section {
+; CHECK:     Name: .text._start
+; CHECK:     Type: SHT_PROGBITS
+; CHECK:     Flags [ (0x6)
+; CHECK:       SHF_ALLOC
+; CHECK:       SHF_EXECINSTR
+; CHECK:     ]
+; CHECK:   }
+; CHECK:   Section {
+; CHECK:     Name: .rel.text._start
+; CHECK:     Type: SHT_REL
+; CHECK:     Flags [ (0x0)
+; CHECK:     ]
+; CHECK:     )
+; CHECK:   }
+
+; CHECK: Relocations [
+; CHECK:   Section ({{[0-9]+}}) .rel.text.foo {
+; CHECK:     0x21 R_386_PC32 memcpy 0x0
+; CHECK:   }
+;   Relocation can be against the start of the section or
+;   the function's symbol itself.
+; CHECK:   Section ({{[0-9]+}}) .rel.text._start {
+; CHECK:     0x13 R_386_PC32 {{.*}}bar 0x0
+; CHECK:     0x25 R_386_PC32 {{.*}}foo 0x0
+; CHECK:   }
+; CHECK: ]
+
+; CHECK: Symbols [
+; CHECK:          Name: bar
+; CHECK:          Name: foo
+; CHECK:          Name: _start
+; CHECK:          Name: memcpy
+; CHECK: ]