From e75b57a1272fdbd3b99c1f3bad38b03c8d37519c Mon Sep 17 00:00:00 2001
From: Joel Dice <joel.dice@gmail.com>
Date: Sat, 25 Sep 2010 15:48:15 -0600
Subject: [PATCH] don't abort when compiling an array lookup with a constant
 negative index

Instead, just compile it as a direct call to the thunk which throws an
ArrayIndexOutOfBoundsException.
---
 src/compiler.cpp | 40 +++++++++++++++++++++++-----------------
 test/Arrays.java | 11 +++++++++++
 2 files changed, 34 insertions(+), 17 deletions(-)

diff --git a/src/compiler.cpp b/src/compiler.cpp
index 44217336a2..5e8c447b7e 100644
--- a/src/compiler.cpp
+++ b/src/compiler.cpp
@@ -4865,12 +4865,13 @@ class BoundsCheckEvent: public Event {
     Assembler* a = c->assembler;
 
     ConstantSite* constant = findConstantSite(c, index);
-    CodePromise* nextPromise = codePromise
-      (c, static_cast<Promise*>(0));
     CodePromise* outOfBoundsPromise = 0;
 
     if (constant) {
-      expect(c, constant->value->value() >= 0);      
+      if (constant->value->value() < 0) {
+        Assembler::Constant handlerConstant(resolved(c, handler));
+        a->apply(Call, BytesPerWord, ConstantOperand, &handlerConstant);
+      }
     } else {
       outOfBoundsPromise = codePromise(c, static_cast<Promise*>(0));
 
@@ -4880,24 +4881,29 @@ class BoundsCheckEvent: public Event {
             BytesPerWord, &oob, &oob);
     }
 
-    assert(c, object->source->type(c) == RegisterOperand);
-    MemorySite length(static_cast<RegisterSite*>(object->source)->number,
-                      lengthOffset, NoRegister, 1);
-    length.acquired = true;
+    if (constant == 0 or constant->value->value() >= 0) {
+      assert(c, object->source->type(c) == RegisterOperand);
+      MemorySite length(static_cast<RegisterSite*>(object->source)->number,
+                        lengthOffset, NoRegister, 1);
+      length.acquired = true;
 
-    ConstantSite next(nextPromise);
-    apply(c, JumpIfGreater, 4, index->source, index->source, 4, &length,
-          &length, BytesPerWord, &next, &next);
+      CodePromise* nextPromise = codePromise
+        (c, static_cast<Promise*>(0));
 
-    if (constant == 0) {
-      outOfBoundsPromise->offset = a->offset();
+      ConstantSite next(nextPromise);
+      apply(c, JumpIfGreater, 4, index->source, index->source, 4, &length,
+            &length, BytesPerWord, &next, &next);
+
+      if (constant == 0) {
+        outOfBoundsPromise->offset = a->offset();
+      }
+
+      Assembler::Constant handlerConstant(resolved(c, handler));
+      a->apply(Call, BytesPerWord, ConstantOperand, &handlerConstant);
+
+      nextPromise->offset = a->offset();
     }
 
-    Assembler::Constant handlerConstant(resolved(c, handler));
-    a->apply(Call, BytesPerWord, ConstantOperand, &handlerConstant);
-
-    nextPromise->offset = a->offset();
-
     popRead(c, this, object);
     popRead(c, this, index);
   }
diff --git a/test/Arrays.java b/test/Arrays.java
index 2dd2bcfc30..52c519ba69 100644
--- a/test/Arrays.java
+++ b/test/Arrays.java
@@ -15,6 +15,17 @@ public class Arrays {
       expect(exception != null);
     }
 
+    { int[] array = new int[0];
+      Exception exception = null;
+      try {
+        int x = array[-1];
+      } catch (ArrayIndexOutOfBoundsException e) {
+        exception = e;
+      }
+
+      expect(exception != null);
+    }
+
     { int[] array = new int[3];
       int i = 0;
       array[i++] = 1;