Align the stack correctly on ARM on calls to fp operation helpers.

Review URL: http://codereview.chromium.org/259013

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3011 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/assembler-arm.h

@@ -645,8 +645,8 @@ class Assembler : public Malloced {
     str(src, MemOperand(sp, 4, NegPreIndex), cond);
   }
 
-  void pop(Register dst) {
-    ldr(dst, MemOperand(sp, 4, PostIndex), al);
+  void pop(Register dst, Condition cond = al) {
+    ldr(dst, MemOperand(sp, 4, PostIndex), cond);
   }
 
   void pop() {

src/arm/codegen-arm.cc

@@ -5061,11 +5061,14 @@ static void HandleBinaryOpSlowCases(MacroAssembler* masm,
   // r5: Address of heap number for result.
   __ push(lr);   // For later.
   __ push(r5);   // Address of heap number that is answer.
+  __ AlignStack(0);
   // Call C routine that may not cause GC or other trouble.
   __ mov(r5, Operand(ExternalReference::double_fp_operation(operation)));
   __ Call(r5);
+  __ pop(r4);  // Address of heap number.
+  __ cmp(r4, Operand(Smi::FromInt(0)));
+  __ pop(r4, eq);  // Conditional pop instruction to get rid of alignment push.
   // Store answer in the overwritable heap number.
-  __ pop(r4);
 #if !defined(USE_ARM_EABI)
   // Double returned in fp coprocessor register 0 and 1, encoded as register
   // cr8.  Offsets must be divisible by 4 for coprocessor so we need to

src/arm/macro-assembler-arm.cc

@@ -291,27 +291,8 @@ void MacroAssembler::EnterExitFrame(StackFrame::Type type) {
 
   // Align the stack at this point.  After this point we have 5 pushes,
   // so in fact we have to unalign here!  See also the assert on the
-  // alignment immediately below.
-#if defined(V8_HOST_ARCH_ARM)
-  // Running on the real platform. Use the alignment as mandated by the local
-  // environment.
-  // Note: This will break if we ever start generating snapshots on one ARM
-  // platform for another ARM platform with a different alignment.
-  int activation_frame_alignment = OS::ActivationFrameAlignment();
-#else  // defined(V8_HOST_ARCH_ARM)
-  // If we are using the simulator then we should always align to the expected
-  // alignment. As the simulator is used to generate snapshots we do not know
-  // if the target platform will need alignment, so we will always align at
-  // this point here.
-  int activation_frame_alignment = 2 * kPointerSize;
-#endif  // defined(V8_HOST_ARCH_ARM)
-  if (activation_frame_alignment != kPointerSize) {
-    // This code needs to be made more general if this assert doesn't hold.
-    ASSERT(activation_frame_alignment == 2 * kPointerSize);
-    mov(r7, Operand(Smi::FromInt(0)));
-    tst(sp, Operand(activation_frame_alignment - 1));
-    push(r7, eq);  // Conditional push instruction.
-  }
+  // alignment in AlignStack.
+  AlignStack(1);
 
   // Push in reverse order: caller_fp, sp_on_exit, and caller_pc.
   stm(db_w, sp, fp.bit() | ip.bit() | lr.bit());
@@ -343,6 +324,30 @@ void MacroAssembler::EnterExitFrame(StackFrame::Type type) {
 }
 
 
+void MacroAssembler::AlignStack(int offset) {
+#if defined(V8_HOST_ARCH_ARM)
+  // Running on the real platform. Use the alignment as mandated by the local
+  // environment.
+  // Note: This will break if we ever start generating snapshots on one ARM
+  // platform for another ARM platform with a different alignment.
+  int activation_frame_alignment = OS::ActivationFrameAlignment();
+#else  // defined(V8_HOST_ARCH_ARM)
+  // If we are using the simulator then we should always align to the expected
+  // alignment. As the simulator is used to generate snapshots we do not know
+  // if the target platform will need alignment, so we will always align at
+  // this point here.
+  int activation_frame_alignment = 2 * kPointerSize;
+#endif  // defined(V8_HOST_ARCH_ARM)
+  if (activation_frame_alignment != kPointerSize) {
+    // This code needs to be made more general if this assert doesn't hold.
+    ASSERT(activation_frame_alignment == 2 * kPointerSize);
+    mov(r7, Operand(Smi::FromInt(0)));
+    tst(sp, Operand(activation_frame_alignment - offset));
+    push(r7, eq);  // Conditional push instruction.
+  }
+}
+
+
 void MacroAssembler::LeaveExitFrame(StackFrame::Type type) {
 #ifdef ENABLE_DEBUGGER_SUPPORT
   // Restore the memory copy of the registers by digging them out from

src/arm/macro-assembler-arm.h

@@ -96,6 +96,8 @@ class MacroAssembler: public Assembler {
   // Leave the current exit frame. Expects the return value in r0.
   void LeaveExitFrame(StackFrame::Type type);
 
+  // Align the stack by optionally pushing a Smi zero.
+  void AlignStack(int offset);
 
   // ---------------------------------------------------------------------------
   // JavaScript invokes