ART: Arm32 packed-switch jump tables

Add jump table support to the thumb2 assembler. Jump tables are
a collection of labels for the case targets, and an anchor label
denoting the position of the jump.

Use the jump table support to implement packed-switch support for
arm32.

Add tests for BindTrackedLabel and JumpTable to the thumb2 assembler
test.

Bug: 24092914
Change-Id: I5c84f193dfebf9e07f48678efc8bd151bb1410dd

1 files changed, 21 insertions, 0 deletions

diff --git a/compiler/utils/arm/assembler_arm.cc b/compiler/utils/arm/assembler_arm.cc
index 807bedaa04..68e39568bb 100644
--- a/compiler/utils/arm/assembler_arm.cc
+++ b/compiler/utils/arm/assembler_arm.cc
@@ -16,6 +16,8 @@
 
 #include "assembler_arm.h"
 
+#include <algorithm>
+
 #include "base/bit_utils.h"
 #include "base/logging.h"
 #include "entrypoints/quick/quick_entrypoints.h"
@@ -922,5 +924,24 @@ uint32_t ArmAssembler::ModifiedImmediate(uint32_t value) {
   return value | i << 26 | imm3 << 12 | a << 7;
 }
 
+void ArmAssembler::FinalizeTrackedLabels() {
+  if (!tracked_labels_.empty()) {
+    // This array should be sorted, as assembly is generated in linearized order. It isn't
+    // technically required, but GetAdjustedPosition() used in AdjustLabelPosition() can take
+    // advantage of it. So ensure that it's actually the case.
+    DCHECK(std::is_sorted(
+        tracked_labels_.begin(),
+        tracked_labels_.end(),
+        [](const Label* lhs, const Label* rhs) { return lhs->Position() < rhs->Position(); }));
+
+    Label* last_label = nullptr;  // Track duplicates, we must not adjust twice.
+    for (Label* label : tracked_labels_) {
+      DCHECK_NE(label, last_label);
+      AdjustLabelPosition(label);
+      last_label = label;
+    }
+  }
+}
+
 }  // namespace arm
 }  // namespace art