From d32f97238c903765dec4e9a9f3cbfa5fd12cded6 Mon Sep 17 00:00:00 2001 From: Cliff Click Date: Mon, 10 Aug 2026 11:11:18 -0700 Subject: Chapter 25: Modules, Separate Compilation, and SSA Construction Co-authored-by: Hsiang-Ying Fu <66062782+fuhsnn@users.noreply.github.com> Co-authored-by: fuhsnn <66062782+fuhsnn@users.noreply.github.com> Co-authored-by: Symious <14933944+symious@users.noreply.github.com> Co-authored-by: Jun Kawasaki Co-authored-by: Claude Opus 5 --- .../com/seaofnodes/simple/codegen/ElfReader.java | 234 +++++++++++++++++++++ 1 file changed, 234 insertions(+) create mode 100644 src/main/java/com/seaofnodes/simple/codegen/ElfReader.java (limited to 'src/main/java/com/seaofnodes/simple/codegen/ElfReader.java') diff --git a/src/main/java/com/seaofnodes/simple/codegen/ElfReader.java b/src/main/java/com/seaofnodes/simple/codegen/ElfReader.java new file mode 100644 index 00000000..534bb10f --- /dev/null +++ b/src/main/java/com/seaofnodes/simple/codegen/ElfReader.java @@ -0,0 +1,234 @@ +package com.seaofnodes.simple.codegen; + +import com.seaofnodes.simple.node.Node; +import com.seaofnodes.simple.type.TypeMemPtr; +import com.seaofnodes.simple.type.TypeStruct; +import com.seaofnodes.simple.util.Ary; +import com.seaofnodes.simple.util.BAOS; +import com.seaofnodes.simple.util.Utils; +import java.io.*; +import java.nio.file.Files; +import java.util.HashMap; + +public class ElfReader { + + public final File _file; + public final byte[] _buf; + int _x; // Cursor into buffer + // ELF Header + public final ElfHeader _header; + // All sections + public final Section[] _sections; + // Simple section, if available + public final Section _simple; + // Byte array in/out stream - used as a reader + public final BAOS _bais; + // Compilation unit; written into FunNodes + public final CompUnit _compunit; + + // Strings from the Simple section, either small public set or whole set + public String[] _strs; + // Dependent file names + public String[] _deps; + // Only published symbol this file + public TypeStruct _clz; + // Canonical named types, distinct from optimized same-named graph states. + public TypeStruct[] _pubTypes; + // Nodes read in this Elf + public Ary _nodes; + + // Load an Elf file (mostly lazily) + public static ElfReader load( File f, CompUnit cu ) { + try { return new ElfReader(f,cu); } + catch( IOException ioe ) { return null; } + } + + // Load the Simple section from the ELF file + private ElfReader( File f, CompUnit cu ) throws IOException { + _file = f; + _compunit = cu; + _buf = Files.readAllBytes(f.toPath()); + _header = new ElfHeader(); + // No attempt is made to parse the program header table. + _sections = new Section[_header._shnum]; + for( int i=0; i<_header._shnum; i++ ) + _sections[i] = new Section(i); + + // Load section names + Section secstr = _sections[_header._shstrndx]; + for( Section sec : _sections ) + if( sec._type != 0 ) + sec._name = secstr.str(sec._noff); + + Section simple = null; + for( Section sec : _sections ) + if( ".simple".equals(sec._name) ) + simple = sec; + _simple = simple; + _bais = new BAOS(_buf, (int)_simple._offset); + } + + // For Serialize self-test + ElfReader( BAOS bais ) { + _file = null; + _compunit = null; + _buf = bais.buf(); + _header = null; + _sections = null; + _simple = null; + _bais = bais; + } + + // Load the public symbols and dependent objs, but not the whole IR + void loadPublicSymbols() { + // Check already loaded and cached + if( _strs == null && _simple != null ) + // Read only the published public strings, for speed purposes when + // scanning a large count of ELF files but getting hits in only a + // few of them. i.e. optimizing (prematurely?) for the traditional + // case of linking a small file against a large library + Serialize.read_public_strs(this); + } + + // Loads the entire IR + public TypeStruct loadSimple(CodeGen code) { + Serialize.readAll(code, this, code._aliases, code._fidxs, code._rpcs); + return _clz; + } + + // Loads strings, mappings, and types, but not Nodes. Used after the + // public-string scan finds a matching Simple ELF, so parsing can resolve + // imported field/array aliases before the full graph is linked in later. + public TypeStruct loadPublicTypes(CodeGen code) { + Serialize.readTypes(code, this, code._aliases, code._fidxs, code._rpcs); + return _clz; + } + + int u1() { return _buf[_x++]&0xFF; } + int magic() { // Big endian + return (u1() << 24) | (u1() << 16) | (u1() << 8) | u1(); + } + int u2() { return u1() | (u1()<<8); } // Little endian + int u4() { // Little endian + return u1() | (u1() << 8) | (u1() << 16) | (u1() << 24); + } + long u8() { return u4() | ((long)u4()<<32); } + void skip(int skip) { _x += skip; } + + + public class ElfHeader { + final int _magic; + final boolean _format32; // Format32 or format64 + final byte _osabi; + final boolean _little; // True if little endian, false if big endian + final char _type; + final char _machine; + final long _entry; // Process entry point + final long _phoff; // Program header table offset, from file start + final long _shoff; // Section header table offset, from file start + final int _flags; // Flags + final int _phnum; // Number of program header entries + final int _shentsize; + final int _shnum; // Number of section header entries + final int _shstrndx; // Section header index contains section names + + + ElfHeader() throws IOException { + _x = 0; + if( (_magic = magic()) != 0x7F454C46 ) bad("magic number",_magic); + byte EI_CLASS = (byte)u1(); + if( EI_CLASS != 1 && EI_CLASS != 2 ) bad("EI_CLASS",EI_CLASS); + _format32 = (EI_CLASS==1); + byte EI_DATA = (byte)u1(); + if( EI_DATA != 1 && EI_DATA != 2 ) bad("EI_DATA",EI_DATA); + _little = EI_DATA == 1; + if( u1() != 1 ) bad("version",1); + if( (_osabi=(byte)u1()) != 0 ) bad("EI_VERSION",_osabi); + byte abiversion = (byte)u1(); + if( abiversion != 0 ) bad("EI_ABIVERSION",abiversion); + skip(7); // Pad + + // Endian matters now + if( !_little ) throw new IOException("TODO: Big endian"); + if( (_type = (char)u2()) != 1 ) bad("ET_REL",_type); + if( (_machine = (char)u2()) != 0x3E ) bad("AMD x86-64",_machine); + int ver = u4(); + if( ver != 1 ) bad("Version",ver); + // Format32 matters now + if( _format32 ) bad("Format",1); + _entry = u8(); // Process entry point + _phoff = u8(); // Program header table offset + _shoff = u8(); // Section header table offset + _flags = u4(); // Flags + int ehsize = u2(); + if( ehsize != 0x40 ) bad("EHSIZE",ehsize); + int phentsize = u2(); + if( phentsize != 0x38 && phentsize != 0 ) bad("PHENTSIZE",phentsize); + _phnum = u2(); + _shentsize = u2(); + if( _shentsize != 0x40 ) bad("SHENTSIZE",_shentsize); + _shnum = u2(); + // String section + _shstrndx = u2(); + assert _x == ehsize; + } + } + + public class Section { + final int _noff; // Offset in string section for name + final int _type; // Section type + final long _flags; + final long _addr; // Offset in virtual mem, if loaded + final long _offset; // Offset in file + final long _size; // Size in bytes + final int _link; // Associated section index, varies + final int _info; // Varies + final byte _align; // Log2 alignment + final int _esize; // Element size, if non-zero + String _name; + + Section(int sidx) throws IOException { + _x = (int)(_header._shoff + (sidx * _header._shentsize)); + _noff = u4(); + _type = u4(); + _flags = u8(); + _addr = u8(); + _offset= u8(); + _size = u8(); + _link = u4(); + _info = u4(); + long align = u8(); + if( align==0 ) align=1; + _align = (byte)Long.numberOfTrailingZeros(align); + if( (1L << _align ) != align ) + throw new IOException("Bad section alignment: "+align); + _esize = (int)u8(); + } + + String str(int off) { + assert _type == 3/*SHT_STRTAB*/; // String table section header + int start = (int)(_offset+off); + int x = start; + while( _buf[x++] !=0 ) ; + return new String(_buf,start,x-start-1); + } + } + + private static void bad(String msg, int val) throws IOException { + throw new IOException("Bad "+msg+": "+val); + } + + + + //public TypeMemPtr lookup( String name ) { + // if( _simple == null ) return null; + // BAOS baos = new BAOS(_buf, (int)_simple._offset); + // Ary strs = Serialize.read_strs(baos); + // + // + // + // Ary nodes = Serialize.read_types(baos); + // + // throw Utils.TODO("Elf load symbol "+name); + //} +} -- cgit v1.2.3