Bug 1024498: Kill NativeFrameSize and rename AsmJSAlignmentAtPrologue into AsmJSSizeOfRetAddr; r=luke

js/src/jit/AsmJS.cpp

@@ -6039,7 +6039,7 @@ LoadJSContextFromActivation(MacroAssembler &masm, Register activation, Register
 static void
 AssertStackAlignment(MacroAssembler &masm)
 {
-    JS_ASSERT((AlignmentAtAsmJSPrologue + masm.framePushed()) % StackAlignment == 0);
+    JS_ASSERT((AsmJSSizeOfRetAddr + masm.framePushed()) % StackAlignment == 0);
 #ifdef DEBUG
     Label ok;
     JS_ASSERT(IsPowerOfTwo(StackAlignment));
@@ -6064,7 +6064,7 @@ StackDecrementForCall(MacroAssembler &masm, unsigned bytesToPush)
 {
     // Include extra padding so that, after pushing the bytesToPush,
     // the stack is aligned for a call instruction.
-    unsigned alreadyPushed = AlignmentAtAsmJSPrologue + masm.framePushed();
+    unsigned alreadyPushed = AsmJSSizeOfRetAddr + masm.framePushed();
     return AlignBytes(alreadyPushed + bytesToPush, StackAlignment) - alreadyPushed;
 }
 
@@ -6109,10 +6109,8 @@ GenerateEntry(ModuleCompiler &m, const AsmJSModule::ExportedFunction &exportedFu
     // PushRegsInMask(NonVolatileRegs).
     masm.setFramePushed(0);
 
+    // See AsmJSSizeOfRetAddr comment in Assembler-*.h.
 #if defined(JS_CODEGEN_ARM)
-    // Push lr without incrementing masm.framePushed since this push is
-    // accounted for by AlignmentAtAsmJSPrologue. The masm.ret at the end will
-    // pop.
     masm.push(lr);
 #endif // JS_CODEGEN_ARM
 #if defined(JS_CODEGEN_MIPS)
@@ -6148,7 +6146,7 @@ GenerateEntry(ModuleCompiler &m, const AsmJSModule::ExportedFunction &exportedFu
     Register argv = ABIArgGenerator::NonArgReturnVolatileReg0;
     Register scratch = ABIArgGenerator::NonArgReturnVolatileReg1;
 #if defined(JS_CODEGEN_X86)
-    masm.loadPtr(Address(StackPointer, NativeFrameSize + masm.framePushed()), argv);
+    masm.loadPtr(Address(StackPointer, AsmJSSizeOfRetAddr + masm.framePushed()), argv);
 #else
     masm.movePtr(IntArgReg0, argv);
 #endif
@@ -6370,10 +6368,8 @@ GenerateFFIInterpreterExit(ModuleCompiler &m, const ModuleCompiler::ExitDescript
     m.setInterpExitOffset(exitIndex);
     masm.setFramePushed(0);
 
+    // See AsmJSSizeOfRetAddr comment in Assembler-*.h.
 #if defined(JS_CODEGEN_ARM)
-    // Push lr without incrementing masm.framePushed since this push is
-    // accounted for by AlignmentAtAsmJSPrologue. The masm.ret at the end will
-    // pop.
     masm.push(lr);
 #endif
 #if defined(JS_CODEGEN_MIPS)
@@ -6397,7 +6393,7 @@ GenerateFFIInterpreterExit(ModuleCompiler &m, const ModuleCompiler::ExitDescript
     masm.reserveStack(stackDec);
 
     // Fill the argument array.
-    unsigned offsetToCallerStackArgs = AlignmentAtAsmJSPrologue + masm.framePushed();
+    unsigned offsetToCallerStackArgs = AsmJSSizeOfRetAddr + masm.framePushed();
     Register scratch = ABIArgGenerator::NonArgReturnVolatileReg0;
     FillArgumentArray(m, exit.sig().args(), offsetToArgv, offsetToCallerStackArgs, scratch);
 
@@ -6546,12 +6542,10 @@ GenerateFFIIonExit(ModuleCompiler &m, const ModuleCompiler::ExitDescriptor &exit
     m.setIonExitOffset(exitIndex);
     masm.setFramePushed(0);
 
+    // See AsmJSSizeOfRetAddr comment in Assembler-*.h.
 #if defined(JS_CODEGEN_X64)
     masm.Push(HeapReg);
 #elif defined(JS_CODEGEN_ARM)
-    // Push lr without incrementing masm.framePushed since this push is
-    // accounted for by AlignmentAtAsmJSPrologue. The masm.ret at the end will
-    // pop.
     masm.push(lr);
 
     // The GlobalReg (r10) and HeapReg (r11) also need to be restored before
@@ -6627,7 +6621,7 @@ GenerateFFIIonExit(ModuleCompiler &m, const ModuleCompiler::ExitDescriptor &exit
     argOffset += sizeof(Value);
 
     // 5. Fill the arguments
-    unsigned offsetToCallerStackArgs = masm.framePushed() + NativeFrameSize;
+    unsigned offsetToCallerStackArgs = masm.framePushed() + AsmJSSizeOfRetAddr;
     FillArgumentArray(m, exit.sig().args(), argOffset, offsetToCallerStackArgs, scratch);
     argOffset += exit.sig().args().length() * sizeof(Value);
     JS_ASSERT(argOffset == offsetToArgs + argBytes);

js/src/jit/CodeGenerator.cpp

@@ -8706,7 +8706,7 @@ CodeGenerator::visitAsmJSCall(LAsmJSCall *ins)
     if (mir->spIncrement())
         masm.freeStack(mir->spIncrement());
 
-    JS_ASSERT((AlignmentAtAsmJSPrologue + masm.framePushed()) % StackAlignment == 0);
+    JS_ASSERT((AsmJSSizeOfRetAddr + masm.framePushed()) % StackAlignment == 0);
 
 #ifdef DEBUG
     Label ok;

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

@@ -138,8 +138,12 @@ static MOZ_CONSTEXPR_VAR FloatRegister d15 = {FloatRegisters::d15};
 static const uint32_t StackAlignment = 8;
 static const uint32_t CodeAlignment = 8;
 static const bool StackKeptAligned = true;
-static const uint32_t NativeFrameSize = sizeof(void*);
-static const uint32_t AlignmentAtAsmJSPrologue = sizeof(void*);
+
+// As an invariant across architectures, within asm.js code:
+//    $sp % StackAlignment = (AsmJSSizeOfRetAddr + masm.framePushed) % StackAlignment
+// To achieve this on ARM, the first instruction of the asm.js prologue pushes
+// lr without incrementing masm.framePushed.
+static const uint32_t AsmJSSizeOfRetAddr = sizeof(void*);
 
 static const Scale ScalePointer = TimesFour;
 

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

@@ -53,6 +53,7 @@ CodeGeneratorARM::generateAsmJSPrologue(Label *stackOverflowLabel)
 {
     JS_ASSERT(gen->compilingAsmJS());
 
+    // See comment in Assembler-arm.h about AsmJSSizeOfRetAddr.
     masm.push(lr);
 
     // The asm.js over-recursed handler wants to be able to assume that SP

js/src/jit/arm/MacroAssembler-arm.cpp

@@ -3876,7 +3876,7 @@ MacroAssemblerARMCompat::callWithABIPre(uint32_t *stackAdjust, bool callFromAsmJ
     if (useHardFpABI())
         *stackAdjust += 2*((usedFloatSlots_ > NumFloatArgRegs) ? usedFloatSlots_ - NumFloatArgRegs : 0) * sizeof(intptr_t);
 #endif
-    uint32_t alignmentAtPrologue = callFromAsmJS ? AlignmentAtAsmJSPrologue : 0;
+    uint32_t alignmentAtPrologue = callFromAsmJS ? AsmJSSizeOfRetAddr : 0;
 
     if (!dynamicAlignment_) {
         *stackAdjust += ComputeByteAlignment(framePushed_ + *stackAdjust + alignmentAtPrologue,

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

@@ -151,9 +151,12 @@ static MOZ_CONSTEXPR_VAR FloatRegister f30 = {FloatRegisters::f30};
 static const uint32_t StackAlignment = 8;
 static const uint32_t CodeAlignment = 4;
 static const bool StackKeptAligned = true;
-// NativeFrameSize is the size of return adress on stack in AsmJS functions.
-static const uint32_t NativeFrameSize = sizeof(void*);
-static const uint32_t AlignmentAtAsmJSPrologue = sizeof(void*);
+
+// As an invariant across architectures, within asm.js code:
+//    $sp % StackAlignment = (AsmJSSizeOfRetAddr + masm.framePushed) % StackAlignment
+// To achieve this on MIPS, the first instruction of the asm.js prologue pushes
+// ra without incrementing masm.framePushed.
+static const uint32_t AsmJSSizeOfRetAddr = sizeof(void*);
 
 static const Scale ScalePointer = TimesFour;
 

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

@@ -52,6 +52,7 @@ CodeGeneratorMIPS::generateAsmJSPrologue(Label *stackOverflowLabel)
 {
     JS_ASSERT(gen->compilingAsmJS());
 
+    // See comment in Assembler-mips.h about AsmJSSizeOfRetAddr.
     masm.push(ra);
 
     // The asm.js over-recursed handler wants to be able to assume that SP

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

@@ -69,7 +69,7 @@ CodeGeneratorShared::CodeGeneratorShared(MIRGenerator *gen, LIRGraph *graph, Mac
         // relies on the a priori stack adjustment (in the prologue) on platforms
         // (like x64) which require the stack to be aligned.
         if (StackKeptAligned || gen->needsInitialStackAlignment()) {
-            unsigned alignmentAtCall = AlignmentAtAsmJSPrologue + frameDepth_;
+            unsigned alignmentAtCall = AsmJSSizeOfRetAddr + frameDepth_;
             if (unsigned rem = alignmentAtCall % StackAlignment)
                 frameDepth_ += StackAlignment - rem;
         }

js/src/jit/shared/CodeGenerator-shared.h

@@ -155,7 +155,7 @@ class CodeGeneratorShared : public LInstructionVisitor
     // For arguments to the current function.
     inline int32_t ArgToStackOffset(int32_t slot) const {
         return masm.framePushed() +
-               (gen->compilingAsmJS() ? NativeFrameSize : sizeof(IonJSFrameLayout)) +
+               (gen->compilingAsmJS() ? AsmJSSizeOfRetAddr : sizeof(IonJSFrameLayout)) +
                slot;
     }
 

js/src/jit/x64/Assembler-x64.h

@@ -182,8 +182,13 @@ static MOZ_CONSTEXPR_VAR Register PreBarrierReg = rdx;
 static const uint32_t StackAlignment = 16;
 static const bool StackKeptAligned = false;
 static const uint32_t CodeAlignment = 8;
-static const uint32_t NativeFrameSize = sizeof(void*);
-static const uint32_t AlignmentAtAsmJSPrologue = sizeof(void*);
+
+// As an invariant across architectures, within asm.js code:
+//   $sp % StackAlignment = (AsmJSSizeOfRetAddr + masm.framePushed) % StackAlignment
+// On x64, this naturally falls out of the fact that the 'call' instruction
+// pushes the return address on the stack and masm.framePushed = 0 at the first
+// instruction of the prologue.
+static const uint32_t AsmJSSizeOfRetAddr = sizeof(void*);
 
 static const Scale ScalePointer = TimesEight;
 

js/src/jit/x86/Assembler-x86.h

@@ -110,8 +110,14 @@ static const uint32_t StackAlignment = 4;
 #endif
 static const bool StackKeptAligned = false;
 static const uint32_t CodeAlignment = 8;
-static const uint32_t NativeFrameSize = sizeof(void*);
-static const uint32_t AlignmentAtAsmJSPrologue = sizeof(void*);
+
+// As an invariant across architectures, within asm.js code:
+//   $sp % StackAlignment = (AsmJSSizeOfRetAddr + masm.framePushed) % StackAlignment
+// On x86, this naturally falls out of the fact that the 'call' instruction
+// pushes the return address on the stack and masm.framePushed = 0 at the first
+// instruction of the prologue.
+static const uint32_t AsmJSSizeOfRetAddr = sizeof(void*);
+
 struct ImmTag : public Imm32
 {
     ImmTag(JSValueTag mask)