Tweaks to IA32 barriers, ensure cheap null test loads from tib offset…

… not field 1 (in case not present). Perform barrier null checks for getfield avoiding 1 load.
codehaus · Mar 1, 2009 · 0486d1b · 0486d1b
1 parent 7f3b83f
commit 0486d1b
Show file tree

Hide file tree

Showing 2 changed files with 4 additions and 25 deletions.
diff --git a/rvm/src/org/jikesrvm/compilers/baseline/ia32/Barriers.java b/rvm/src/org/jikesrvm/compilers/baseline/ia32/Barriers.java
@@ -13,7 +13,6 @@
 package org.jikesrvm.compilers.baseline.ia32;
 
 import org.jikesrvm.Configuration;
-import org.jikesrvm.VM;
 import org.jikesrvm.ArchitectureSpecific.Assembler;
 import org.jikesrvm.ia32.BaselineConstants;
 import org.jikesrvm.runtime.Entrypoints;
@@ -104,19 +103,19 @@ static void compileArrayLoadBarrier(Assembler asm, boolean pushResult) {
   static void compileGetfieldBarrier(Assembler asm, GPR reg, int locationMetadata) {
     //  on entry java stack contains ...|target_ref|
     //  SP -> target_ref
-    genNullCheck(asm, 0);
     asm.emitPUSH_Reg(reg);
     asm.emitPUSH_Imm(locationMetadata);
     BaselineCompilerImpl.genParameterRegisterLoad(asm, 3);
+    BaselineCompilerImpl.genNullCheck(asm, T0);
     asm.emitCALL_Abs(Magic.getTocPointer().plus(Entrypoints.getfieldReadBarrierMethod.getOffset()));
     asm.emitPUSH_Reg(T0);
   }
 
   static void compileGetfieldBarrierImm(Assembler asm, Offset fieldOffset, int locationMetadata) {
-    genNullCheck(asm, 0);
     asm.emitPUSH_Imm(fieldOffset.toInt());
     asm.emitPUSH_Imm(locationMetadata);
     BaselineCompilerImpl.genParameterRegisterLoad(asm, 3);
+    BaselineCompilerImpl.genNullCheck(asm, T0);
     asm.emitCALL_Abs(Magic.getTocPointer().plus(Entrypoints.getfieldReadBarrierMethod.getOffset()));
     asm.emitPUSH_Reg(T0);
   }
@@ -137,27 +136,6 @@ static void compileGetstaticBarrierImm(Assembler asm, Offset fieldOffset, int lo
     asm.emitPUSH_Reg(T0);
   }
 
-  /**
-   * Generate a cheap nullcheck by attempting to load the TIB of the object
-   * at the given offset to SP.
-   */
-  private static void genNullCheck(Assembler asm, int offset) {
-    if (VM.BuildFor32Addr) {
-      if (offset == 0) {
-        asm.emitMOV_Reg_RegInd(T1, SP);
-      } else {
-        asm.emitMOV_Reg_RegDisp(T1, SP, Offset.fromIntZeroExtend(offset));
-      }
-    } else {
-      if (offset == 0) {
-        asm.emitMOV_Reg_RegInd_Quad(T1, SP);
-      } else {
-        asm.emitMOV_Reg_RegDisp_Quad(T1, SP, Offset.fromIntZeroExtend(offset));
-      }
-    }
-    BaselineCompilerImpl.baselineEmitLoadTIB(asm, T1, T1);
-  }
-
   static void compileModifyCheck(Assembler asm, int offset) {
     if (!Configuration.ExtremeAssertions) return;
     // on entry java stack contains ... [SP+offset] -> target_ref

diff --git a/rvm/src/org/jikesrvm/compilers/baseline/ia32/BaselineCompilerImpl.java b/rvm/src/org/jikesrvm/compilers/baseline/ia32/BaselineCompilerImpl.java
@@ -41,6 +41,7 @@
 import org.jikesrvm.jni.ia32.JNICompiler;
 import org.jikesrvm.mm.mminterface.MemoryManager;
 import org.jikesrvm.mm.mminterface.MemoryManagerConstants;
+import org.jikesrvm.objectmodel.JavaHeader;
 import org.jikesrvm.objectmodel.JavaHeaderConstants;
 import org.jikesrvm.objectmodel.ObjectModel;
 import org.jikesrvm.runtime.ArchEntrypoints;
@@ -3930,7 +3931,7 @@ static void genNullCheck(Assembler asm, GPR objRefReg) {
     boolean cheapTest = true;
     if (cheapTest) {
       // perform load to cause trap
-      asm.emitTEST_RegInd_Reg(objRefReg, objRefReg);
+      asm.emitTEST_RegDisp_Reg(objRefReg, JavaHeader.getTibOffset(), objRefReg);
     } else {
       // compare to zero
       asm.emitTEST_Reg_Reg(objRefReg, objRefReg);