Use mmapped boot image class table for PIC app HLoadClass.

Implement new HLoadClass load kind for boot image classes
referenced by PIC-compiled apps (i.e. prebuilts) that uses
PC-relative load from a boot image ClassTable mmapped into
the apps .bss. This reduces the size of the PIC prebuilts
that reference boot image classes compared to the kBssEntry
as we can completely avoid the slow path and stack map
unless we need to do the class initialization check.

Prebuilt services.odex for aosp_angler-userdebug (arm64):
  - before: 20312800
  - after: 19775352 (-525KiB)

Test: m test-art-host-gtest
Test: testrunner.py --host
Test: testrunner.py --host --pictest
Test: testrunner.py --target on Nexus 6P.
Test: testrunner.py --target --pictest on Nexus 6P.
Test: Nexus 6P boots.
Bug: 31951624
Change-Id: I13adb19a1fa7d095a72a41f09daa6101876e77a8

1 files changed, 23 insertions, 1 deletions

diff --git a/compiler/optimizing/code_generator_mips.cc b/compiler/optimizing/code_generator_mips.cc
index ac8f675e2d..f0ef0071b6 100644
--- a/compiler/optimizing/code_generator_mips.cc
+++ b/compiler/optimizing/code_generator_mips.cc
@@ -20,6 +20,7 @@
 #include "arch/mips/entrypoints_direct_mips.h"
 #include "arch/mips/instruction_set_features_mips.h"
 #include "art_method.h"
+#include "class_table.h"
 #include "code_generator_utils.h"
 #include "compiled_method.h"
 #include "entrypoints/quick/quick_entrypoints.h"
@@ -1664,7 +1665,8 @@ void CodeGeneratorMIPS::EmitLinkerPatches(ArenaVector<LinkerPatch>* linker_patch
                                                                   linker_patches);
   } else {
     DCHECK(pc_relative_method_patches_.empty());
-    DCHECK(pc_relative_type_patches_.empty());
+    EmitPcRelativeLinkerPatches<LinkerPatch::TypeClassTablePatch>(pc_relative_type_patches_,
+                                                                  linker_patches);
     EmitPcRelativeLinkerPatches<LinkerPatch::StringInternTablePatch>(pc_relative_string_patches_,
                                                                      linker_patches);
   }
@@ -7413,6 +7415,7 @@ HLoadClass::LoadKind CodeGeneratorMIPS::GetSupportedLoadClassKind(
       fallback_load = false;
       break;
     case HLoadClass::LoadKind::kBootImageLinkTimePcRelative:
+    case HLoadClass::LoadKind::kBootImageClassTable:
     case HLoadClass::LoadKind::kBssEntry:
       DCHECK(!Runtime::Current()->UseJitCompilation());
       break;
@@ -7643,6 +7646,7 @@ void LocationsBuilderMIPS::VisitLoadClass(HLoadClass* cls) {
     // We need an extra register for PC-relative literals on R2.
     case HLoadClass::LoadKind::kBootImageLinkTimePcRelative:
     case HLoadClass::LoadKind::kBootImageAddress:
+    case HLoadClass::LoadKind::kBootImageClassTable:
     case HLoadClass::LoadKind::kBssEntry:
       if (isR6) {
         break;
@@ -7741,6 +7745,24 @@ void InstructionCodeGeneratorMIPS::VisitLoadClass(HLoadClass* cls) NO_THREAD_SAF
                      codegen_->DeduplicateBootImageAddressLiteral(address));
       break;
     }
+    case HLoadClass::LoadKind::kBootImageClassTable: {
+      DCHECK(!codegen_->GetCompilerOptions().IsBootImage());
+      CodeGeneratorMIPS::PcRelativePatchInfo* info_high =
+          codegen_->NewPcRelativeTypePatch(cls->GetDexFile(), cls->GetTypeIndex());
+      CodeGeneratorMIPS::PcRelativePatchInfo* info_low =
+          codegen_->NewPcRelativeTypePatch(cls->GetDexFile(), cls->GetTypeIndex(), info_high);
+      codegen_->EmitPcRelativeAddressPlaceholderHigh(info_high,
+                                                     out,
+                                                     base_or_current_method_reg);
+      __ Lw(out, out, /* placeholder */ 0x5678, &info_low->label);
+      // Extract the reference from the slot data, i.e. clear the hash bits.
+      int32_t masked_hash = ClassTable::TableSlot::MaskHash(
+          ComputeModifiedUtf8Hash(cls->GetDexFile().StringByTypeIdx(cls->GetTypeIndex())));
+      if (masked_hash != 0) {
+        __ Addiu(out, out, -masked_hash);
+      }
+      break;
+    }
     case HLoadClass::LoadKind::kBssEntry: {
       bss_info_high = codegen_->NewTypeBssEntryPatch(cls->GetDexFile(), cls->GetTypeIndex());
       CodeGeneratorMIPS::PcRelativePatchInfo* info_low =