Bug 1058587 - OdinMonkey MIPS: bias the global-register to improve instruction encoding efficiency. r=dougc

js/src/asmjs/AsmJSValidate.cpp

@@ -6651,10 +6651,11 @@ GenerateAsyncInterruptExit(ModuleCompiler &m, Label *throwLabel)
 
     // Pop resumePC into PC. Clobber HeapReg to make the jump and restore it
     // during jump delay slot.
-    JS_ASSERT(Imm16::IsInSignedRange(AsmJSModule::heapGlobalDataOffset()));
+    JS_ASSERT(Imm16::IsInSignedRange(AsmJSModule::heapGlobalDataOffset() - AsmJSGlobalRegBias));
     masm.pop(HeapReg);
     masm.as_jr(HeapReg);
-    masm.loadPtr(Address(GlobalReg, AsmJSModule::heapGlobalDataOffset()), HeapReg);
+    masm.loadPtr(Address(GlobalReg, AsmJSModule::heapGlobalDataOffset() - AsmJSGlobalRegBias),
+                 HeapReg);
 #elif defined(JS_CODEGEN_ARM)
     masm.setFramePushed(0);         // set to zero so we can use masm.framePushed() below
     masm.PushRegsInMask(RegisterSet(GeneralRegisterSet(Registers::AllMask & ~(1<<Registers::sp)), FloatRegisterSet(uint32_t(0))));   // save all GP registers,excep sp

js/src/jit/mips/Assembler-mips.h

@@ -119,6 +119,11 @@ static MOZ_CONSTEXPR_VAR FloatRegister ScratchDoubleReg = { FloatRegisters::f18,
 static MOZ_CONSTEXPR_VAR FloatRegister SecondScratchFloat32Reg = { FloatRegisters::f16, FloatRegister::Single };
 static MOZ_CONSTEXPR_VAR FloatRegister SecondScratchDoubleReg = { FloatRegisters::f16, FloatRegister::Double };
 
+// A bias applied to the GlobalReg to allow the use of instructions with small
+// negative immediate offsets which doubles the range of global data that can be
+// accessed with a single instruction.
+static const int32_t AsmJSGlobalRegBias = 32768;
+
 // Registers used in the GenerateFFIIonExit Enable Activation block.
 static MOZ_CONSTEXPR_VAR Register AsmJSIonExitRegCallee = t0;
 static MOZ_CONSTEXPR_VAR Register AsmJSIonExitRegE0 = a0;

js/src/jit/mips/CodeGenerator-mips.cpp

@@ -1954,9 +1954,11 @@ CodeGeneratorMIPS::visitAsmJSLoadHeap(LAsmJSLoadHeap *ins)
     // Offset is out of range. Load default values.
     if (isFloat) {
         if (size == 32)
-            masm.loadFloat32(Address(GlobalReg, AsmJSNaN32GlobalDataOffset), ToFloatRegister(out));
+            masm.loadFloat32(Address(GlobalReg, AsmJSNaN32GlobalDataOffset - AsmJSGlobalRegBias),
+                             ToFloatRegister(out));
         else
-            masm.loadDouble(Address(GlobalReg, AsmJSNaN64GlobalDataOffset), ToFloatRegister(out));
+            masm.loadDouble(Address(GlobalReg, AsmJSNaN64GlobalDataOffset - AsmJSGlobalRegBias),
+                            ToFloatRegister(out));
     } else {
         masm.move32(Imm32(0), ToRegister(out));
     }
@@ -2147,7 +2149,7 @@ bool
 CodeGeneratorMIPS::visitAsmJSLoadGlobalVar(LAsmJSLoadGlobalVar *ins)
 {
     const MAsmJSLoadGlobalVar *mir = ins->mir();
-    unsigned addr = mir->globalDataOffset();
+    unsigned addr = mir->globalDataOffset() - AsmJSGlobalRegBias;
     if (mir->type() == MIRType_Int32)
         masm.load32(Address(GlobalReg, addr), ToRegister(ins->output()));
     else if (mir->type() == MIRType_Float32)
@@ -2164,7 +2166,7 @@ CodeGeneratorMIPS::visitAsmJSStoreGlobalVar(LAsmJSStoreGlobalVar *ins)
 
     MIRType type = mir->value()->type();
     MOZ_ASSERT(IsNumberType(type));
-    unsigned addr = mir->globalDataOffset();
+    unsigned addr = mir->globalDataOffset() - AsmJSGlobalRegBias;
     if (mir->value()->type() == MIRType_Int32)
         masm.store32(ToRegister(ins->value()), Address(GlobalReg, addr));
     else if (mir->value()->type() == MIRType_Float32)
@@ -2182,7 +2184,7 @@ CodeGeneratorMIPS::visitAsmJSLoadFuncPtr(LAsmJSLoadFuncPtr *ins)
     Register index = ToRegister(ins->index());
     Register tmp = ToRegister(ins->temp());
     Register out = ToRegister(ins->output());
-    unsigned addr = mir->globalDataOffset();
+    unsigned addr = mir->globalDataOffset() - AsmJSGlobalRegBias;
 
     BaseIndex source(GlobalReg, index, TimesFour, addr);
     masm.load32(source, out);
@@ -2193,7 +2195,8 @@ bool
 CodeGeneratorMIPS::visitAsmJSLoadFFIFunc(LAsmJSLoadFFIFunc *ins)
 {
     const MAsmJSLoadFFIFunc *mir = ins->mir();
-    masm.loadPtr(Address(GlobalReg, mir->globalDataOffset()), ToRegister(ins->output()));
+    masm.loadPtr(Address(GlobalReg, mir->globalDataOffset() - AsmJSGlobalRegBias),
+                 ToRegister(ins->output()));
     return true;
 }
 

js/src/jit/mips/MacroAssembler-mips.h

@@ -1283,7 +1283,7 @@ public:
 #endif
 
     void loadAsmJSActivation(Register dest) {
-        loadPtr(Address(GlobalReg, AsmJSActivationGlobalDataOffset), dest);
+        loadPtr(Address(GlobalReg, AsmJSActivationGlobalDataOffset - AsmJSGlobalRegBias), dest);
     }
 };