commit 08c3bcd66dc0101720da78c1d5f49230f4521c75
author Jan Voung <jvoung@chromium.org> Mon Dec 01 17:55:16 2014 -0800
committer Jan Voung <jvoung@chromium.org> Mon Dec 01 17:55:16 2014 -0800
tree 290fea00c6e1ab92349db3e80f10ac876e0f364f
parent 2f6f8605b944b17a307425a81013b51b5a00a1d3

Subzero: Add basic ELFObjectWriter (text section, symtab, strtab, headers).

Able to write out the ELF file header w/ a text section,
a symbol table, and string table. Write text buffer
directly to file after translating each CFG.
This means that the header is written out early w/ fake
data and then we seek back and write the real header
at the very end.

Does not yet handle relocations, data, rodata, constant
pools, bss, or -ffunction-sections, more than 64K sections
or more than 2^24 symbols.

Numbers w/ current NOASSERT=1 build on 176.gcc:

w/out -elf-writer:
    0.233771 (21.1%): [ 1287] emit
    28MB .s file

w/ -elf-writer:
    0.051056 ( 5.6%): [ 1287] emit
    2.4MB .o file

BUG=none
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/678533005

src/assembler.h

diff --git a/src/assembler.h b/src/assembler.h
index 37963c4..dc70668 100644
--- a/src/assembler.h
+++ b/src/assembler.h
@@ -35,7 +35,6 @@
 class AssemblerFixup;
 class AssemblerBuffer;
 class ConstantRelocatable;
-class MemoryRegion;
 
 // Assembler fixups are positions in generated code that hold relocation
 // information that needs to be processed before finalizing the code
@@ -45,7 +44,6 @@
   AssemblerFixup &operator=(const AssemblerFixup &) = delete;
 
 public:
-  virtual void Process(const MemoryRegion &region, intptr_t position) = 0;
 
   // It would be ideal if the destructor method could be made private,
   // but the g++ compiler complains when this is subclassed.
@@ -109,12 +107,6 @@
   intptr_t Size() const { return cursor_ - contents_; }
   uintptr_t contents() const { return contents_; }
 
-  // Copy the assembled instructions into the specified memory block
-  // and apply all fixups.
-  // TODO(jvoung): This will be different. We'll be writing the text
-  // and reloc section to a file?
-  void FinalizeInstructions(const MemoryRegion &region);
-
 // To emit an instruction to the assembler buffer, the EnsureCapacity helper
 // must be used to guarantee that the underlying data area is big enough to
 // hold the emitted instruction. Usage:
@@ -189,9 +181,6 @@
     return (limit_ - contents_) + kMinimumGap;
   }
 
-  // Process the fixup chain.
-  void ProcessFixups(const MemoryRegion &region);
-
   // Compute the limit based on the data area and the capacity. See
   // description of kMinimumGap for the reasoning behind the value.
   static uintptr_t ComputeLimit(uintptr_t data, intptr_t capacity) {
@@ -226,8 +215,20 @@
   // Allocate data of type T using the per-Assembler allocator.
   template <typename T> T *Allocate() { return Allocator.Allocate<T>(); }
 
+  // Align the tail end of the function to the required target alignment.
+  virtual void alignFunction() = 0;
+
+  virtual SizeT getBundleAlignLog2Bytes() const = 0;
+
+  virtual llvm::ArrayRef<uint8_t> getNonExecBundlePadding() const = 0;
+
+  // Mark the current text location as the start of a CFG node
+  // (represented by NodeNumber).
   virtual void BindCfgNodeLabel(SizeT NodeNumber) = 0;
 
+  // Return a view of all the bytes of code for the current function.
+  llvm::StringRef getBufferView() const;
+
   void emitIASBytes(GlobalContext *Ctx) const;
 
 private: