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authorKartik Agaram <vc@akkartik.com>2019-07-27 16:01:55 -0700
committerKartik Agaram <vc@akkartik.com>2019-07-27 17:47:59 -0700
commit6e1eeeebfb453fa7c871869c19375ce60fbd7413 (patch)
tree539c4a3fdf1756ae79770d5c4aaf6366f1d1525e /subx/034compute_segment_address.cc
parent8846a7f85cc04b77b2fe8a67b6d317723437b00c (diff)
downloadmu-6e1eeeebfb453fa7c871869c19375ce60fbd7413.tar.gz
5485 - promote SubX to top-level
Diffstat (limited to 'subx/034compute_segment_address.cc')
-rw-r--r--subx/034compute_segment_address.cc86
1 files changed, 0 insertions, 86 deletions
diff --git a/subx/034compute_segment_address.cc b/subx/034compute_segment_address.cc
deleted file mode 100644
index 61c3739a..00000000
--- a/subx/034compute_segment_address.cc
+++ /dev/null
@@ -1,86 +0,0 @@
-//: ELF binaries have finicky rules about the precise alignment each segment
-//: should start at. They depend on the amount of code in a program.
-//: We shouldn't expect people to adjust segment addresses everytime they make
-//: a change to their programs.
-//: Let's start taking the given segment addresses as guidelines, and adjust
-//: them as necessary.
-//: This gives up a measure of control in placing code and data.
-
-void test_segment_name() {
-  run(
-      "== code 0x09000000\n"
-      "05/add-to-EAX  0x0d0c0b0a/imm32\n"
-      // code starts at 0x09000000 + p_offset, which is 0x54 for a single-segment binary
-  );
-  CHECK_TRACE_CONTENTS(
-      "load: 0x09000054 -> 05\n"
-      "load: 0x09000055 -> 0a\n"
-      "load: 0x09000056 -> 0b\n"
-      "load: 0x09000057 -> 0c\n"
-      "load: 0x09000058 -> 0d\n"
-      "run: add imm32 0x0d0c0b0a to EAX\n"
-      "run: storing 0x0d0c0b0a\n"
-  );
-}
-
-//: compute segment address
-
-:(before "End Level-2 Transforms")
-Transform.push_back(compute_segment_starts);
-
-:(code)
-void compute_segment_starts(program& p) {
-  trace(3, "transform") << "-- compute segment addresses" << end();
-  uint32_t p_offset = /*size of ehdr*/0x34 + SIZE(p.segments)*0x20/*size of each phdr*/;
-  for (size_t i = 0;  i < p.segments.size();  ++i) {
-    segment& curr = p.segments.at(i);
-    if (curr.start >= 0x08000000) {
-      // valid address for user space, so assume we're creating a real ELF binary, not just running a test
-      curr.start &= 0xfffff000;  // same number of zeros as the p_align used when emitting the ELF binary
-      curr.start |= (p_offset & 0xfff);
-      trace(99, "transform") << "segment " << i << " begins at address 0x" << HEXWORD << curr.start << end();
-    }
-    p_offset += size_of(curr);
-    assert(p_offset < SEGMENT_ALIGNMENT);  // for now we get less and less available space in each successive segment
-  }
-}
-
-uint32_t size_of(const segment& s) {
-  uint32_t sum = 0;
-  for (int i = 0;  i < SIZE(s.lines);  ++i)
-    sum += num_bytes(s.lines.at(i));
-  return sum;
-}
-
-// Assumes all bitfields are packed.
-uint32_t num_bytes(const line& inst) {
-  uint32_t sum = 0;
-  for (int i = 0;  i < SIZE(inst.words);  ++i)
-    sum += size_of(inst.words.at(i));
-  return sum;
-}
-
-int size_of(const word& w) {
-  if (has_operand_metadata(w, "disp32") || has_operand_metadata(w, "imm32"))
-    return 4;
-  else if (has_operand_metadata(w, "disp16"))
-    return 2;
-  // End size_of(word w) Special-cases
-  else
-    return 1;
-}
-
-//: Dependencies:
-//: - We'd like to compute segment addresses before setting up global variables,
-//:   because computing addresses for global variables requires knowing where
-//:   the data segment starts.
-//: - We'd like to finish expanding labels before computing segment addresses,
-//:   because it would make computing the sizes of segments more self-contained
-//:   (num_bytes).
-//:
-//: Decision: compute segment addresses before expanding labels, by being
-//: aware in this layer of certain operand types that will eventually occupy
-//: multiple bytes.
-//:
-//: The layer to expand labels later hooks into num_bytes() to teach this
-//: layer that labels occupy zero space in the binary.