JIT: Performance fix for const doubles

Some recent Arm processors take a performance hit when
creating a floating point double by loading it as a pair of singles.
Legacy code to support soft floating point doubles as a pair of core
registers loaded double immediates in this way.

With the CL, we handle double immediates as a single unit.

Change-Id: I91aca9da6d4b38e180479dd8f75c82dbc7b4a526

1 files changed, 27 insertions, 0 deletions

diff --git a/vm/compiler/codegen/arm/CodegenCommon.cpp b/vm/compiler/codegen/arm/CodegenCommon.cpp
index 07f3ac765..5c02678fe 100644
--- a/vm/compiler/codegen/arm/CodegenCommon.cpp
+++ b/vm/compiler/codegen/arm/CodegenCommon.cpp
@@ -368,6 +368,25 @@ static ArmLIR *scanLiteralPool(LIR *dataTarget, int value, unsigned int delta)
     return NULL;
 }
 
+/* Search the existing constants in the literal pool for an exact wide match */
+ArmLIR* scanLiteralPoolWide(LIR* dataTarget, int valLo, int valHi)
+{
+  bool lowMatch = false;
+  ArmLIR* lowTarget = NULL;
+  while (dataTarget) {
+    if (lowMatch && (((ArmLIR *)dataTarget)->operands[0] == valHi)) {
+      return lowTarget;
+    }
+    lowMatch = false;
+    if (((ArmLIR *) dataTarget)->operands[0] == valLo) {
+      lowMatch = true;
+      lowTarget = (ArmLIR *) dataTarget;
+    }
+    dataTarget = dataTarget->next;
+  }
+  return NULL;
+}
+
 /*
  * The following are building blocks to insert constants into the pool or
  * instruction streams.
@@ -392,6 +411,14 @@ static ArmLIR *addWordData(CompilationUnit *cUnit, LIR **constantListP,
     return NULL;
 }
 
+/* Add a 64-bit constant to the literal pool or mixed with code */
+ArmLIR* addWideData(CompilationUnit* cUnit, LIR** constantListP,
+                 int valLo, int valHi)
+{
+    addWordData(cUnit, constantListP, valHi);
+    return addWordData(cUnit, constantListP, valLo);
+}
+
 static RegLocation inlinedTargetWide(CompilationUnit *cUnit, MIR *mir,
                                       bool fpHint)
 {