[merc2] Support emerc (#2147)

This adds environment mapping support to `Merc2`, and turns it on for
Jak 1 and Jak 2.

- The performance is much better
- Jak 1 can be toggled back to the old behavior with `(set! *emerc-hack*
#f)`. The new environment mapping is identical to the old one everywhere
I checked.
- Jak 1 still falls back to generic for ripple/texscroll/blerc/eyes -
there's still no dynamic texture or vertex updating support. The eye
detection stuff will sometimes flag stuff as eyes which is not eyes,
which is fine, but means that generic will be used in some places where
emerc could be used. For example, the shiny plates on jak's arm will be
drawn with generic because jak has eyes.
- Jak 2 hasn't been checked super carefully against PCSX2 yet.
- Jak 2 still isn't technically using emerc, but instead putting emerc
models in the merc bucket.
- The interface to merc is a lot different now and totally custom
OpenGOAL DMA code. The original merc drawing asm doesn't run anymore.
- The FR3 format changed
- Something funky going on with foreground lighting in escape, but
doesn't seem to be related to this change?

Performance comparison, jak 1, in likely the most generic-merc heavy
spot:

![image](https://user-images.githubusercontent.com/48171810/213882718-feb2ab59-95a9-44a2-b0e5-95fba860c7b0.png)

![image](https://user-images.githubusercontent.com/48171810/213882736-8dbbf4c9-6bbf-4d0b-96ce-78d63274660c.png)

decompiler/level_extractor/MercData.cpp

@@ -2,6 +2,7 @@
 
 #include "common/dma/gs.h"
 
+#include "decompiler/ObjectFile/LinkedObjectFile.h"
 #include "decompiler/util/DecompilerTypeSystem.h"
 
 #include "third-party/fmt/core.h"
@@ -199,6 +200,44 @@ std::string MercShader::print() const {
   return result;
 }
 
+MercShader make_shader(Ref& ref, bool expected_eop) {
+  // adgif0
+  MercShader shader;
+  u8 adgif0_addr = deref_u8(ref, 8);
+  ASSERT(adgif0_addr == (u8)GsRegisterAddress::TEX0_1);
+  shader.output_offset = deref_u32(ref, 3);
+  shader.tex0 = GsTex0(deref_u64(ref, 0));
+  ref.byte_offset += 16;
+
+  // adgif1
+  u8 adgif1_addr = deref_u8(ref, 8);
+  ASSERT(adgif1_addr == (u8)GsRegisterAddress::TEX1_1);
+  shader.tex1 = GsTex1(deref_u64(ref, 0));
+  u16 stash = deref_u32(ref, 3);
+  shader.original_tex = deref_u32(ref, 2);
+  shader.next_strip_nloop = stash & 0x7fff;
+  ASSERT((!!(stash & 0x8000)) == expected_eop);  // set eop on last
+  ref.byte_offset += 16;
+
+  // adgif2
+  u8 adgif2_addr = deref_u8(ref, 8);
+  ASSERT(adgif2_addr == (u8)GsRegisterAddress::MIPTBP1_1);
+  ref.byte_offset += 16;
+
+  // adgif3
+  u8 adgif3_addr = deref_u8(ref, 8);
+  ASSERT(adgif3_addr == (u8)GsRegisterAddress::CLAMP_1);
+  shader.clamp = deref_u64(ref, 0);
+  ref.byte_offset += 16;
+
+  // adgif4
+  u8 adgif4_addr = deref_u8(ref, 8);
+  ASSERT(adgif4_addr == (u8)GsRegisterAddress::ALPHA_1);
+  shader.alpha = GsAlpha(deref_u64(ref, 0));
+  ref.byte_offset += 16;
+  return shader;
+}
+
 TypedRef MercFragment::from_ref(TypedRef tr,
                                 const DecompilerTypeSystem& dts,
                                 const MercFragmentControl& control,
@@ -265,40 +304,8 @@ TypedRef MercFragment::from_ref(TypedRef tr,
 
   // fp shaders
   for (int i = 0; i < fp_header.shader_cnt; i++) {
-    auto& shader = shaders.emplace_back();
-    // adgif0
-    u8 adgif0_addr = deref_u8(fp_ref, 8);
-    ASSERT(adgif0_addr == (u8)GsRegisterAddress::TEX0_1);
-    shader.output_offset = deref_u32(fp_ref, 3);
-    shader.tex0 = GsTex0(deref_u64(fp_ref, 0));
-    fp_ref.byte_offset += 16;
-
-    // adgif1
-    u8 adgif1_addr = deref_u8(fp_ref, 8);
-    ASSERT(adgif1_addr == (u8)GsRegisterAddress::TEX1_1);
-    shader.tex1 = GsTex1(deref_u64(fp_ref, 0));
-    u16 stash = deref_u32(fp_ref, 3);
-    shader.original_tex = deref_u32(fp_ref, 2);
-    shader.next_strip_nloop = stash & 0x7fff;
-    ASSERT((!!(stash & 0x8000)) == (i == fp_header.shader_cnt - 1));  // set eop on last
-    fp_ref.byte_offset += 16;
-
-    // adgif2
-    u8 adgif2_addr = deref_u8(fp_ref, 8);
-    ASSERT(adgif2_addr == (u8)GsRegisterAddress::MIPTBP1_1);
-    fp_ref.byte_offset += 16;
-
-    // adgif3
-    u8 adgif3_addr = deref_u8(fp_ref, 8);
-    ASSERT(adgif3_addr == (u8)GsRegisterAddress::CLAMP_1);
-    shader.clamp = deref_u64(fp_ref, 0);
-    fp_ref.byte_offset += 16;
-
-    // adgif4
-    u8 adgif4_addr = deref_u8(fp_ref, 8);
-    ASSERT(adgif4_addr == (u8)GsRegisterAddress::ALPHA_1);
-    shader.alpha = GsAlpha(deref_u64(fp_ref, 0));
-    fp_ref.byte_offset += 16;
+    bool expected_eop = (i == fp_header.shader_cnt - 1);
+    shaders.push_back(make_shader(fp_ref, expected_eop));
   }
 
   tr.ref.byte_offset += (header.mm_quadword_size) * 16;
@@ -361,6 +368,19 @@ void MercEffect::from_ref(TypedRef tr,
   for (u32 i = 0; i < frag_count; i++) {
     f = frag_geo.emplace_back().from_ref(f, dts, frag_ctrl.at(i), main_control);
   }
+
+  // do extra info
+  auto fr = get_field_ref(tr, "extra-info", dts);
+  const auto& word = fr.data->words_by_seg.at(fr.seg).at(fr.byte_offset / 4);
+  if (word.kind() == LinkedWord::PTR) {
+    TypedRef mei(deref_label(fr), dts.ts.lookup_type("merc-extra-info"));
+    u8 shader_offset = read_plain_data_field<u8>(mei, "shader-offset", dts);
+    if (shader_offset) {
+      Ref r = mei.ref;
+      r.byte_offset += 16 * shader_offset;
+      extra_info.shader = make_shader(r, false);
+    }
+  }
 }
 
 std::string MercEffect::print() {