MIPS: Remove frame pointer from StackHandler.

Port 36e69a91

Original commit message:
This reduces the size of the StackHandler by yet another word. We no
longer need to keep track of the frame pointer, as the stack walk will
be able to recalculate it.

BUG=

Review URL: https://codereview.chromium.org/997663002

Cr-Commit-Position: refs/heads/master@{#27123}

src/mips/macro-assembler-mips.cc

@@ -3238,11 +3238,10 @@ void MacroAssembler::DebugBreak() {
 void MacroAssembler::PushTryHandler(StackHandler::Kind kind,
                                     int handler_index) {
   // Adjust this code if not the case.
-  STATIC_ASSERT(StackHandlerConstants::kSize == 4 * kPointerSize);
+  STATIC_ASSERT(StackHandlerConstants::kSize == 3 * kPointerSize);
   STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0 * kPointerSize);
   STATIC_ASSERT(StackHandlerConstants::kStateOffset == 1 * kPointerSize);
   STATIC_ASSERT(StackHandlerConstants::kContextOffset == 2 * kPointerSize);
-  STATIC_ASSERT(StackHandlerConstants::kFPOffset == 3 * kPointerSize);
 
   // For the JSEntry handler, we must preserve a0-a3 and s0.
   // t1-t3 are available. We will build up the handler from the bottom by
@@ -3253,15 +3252,14 @@ void MacroAssembler::PushTryHandler(StackHandler::Kind kind,
       StackHandler::KindField::encode(kind);
   li(t2, Operand(state));
 
-  // Push the frame pointer, context, and state.
+  // Push the context and state.
   if (kind == StackHandler::JS_ENTRY) {
-    DCHECK_EQ(static_cast<Smi*>(0), Smi::FromInt(0));
-    // The second zero_reg indicates no context.
-    // The first zero_reg is the NULL frame pointer.
+    DCHECK(Smi::FromInt(0) == 0);
+    // The zero_reg indicates no context.
     // The operands are reversed to match the order of MultiPush/Pop.
-    Push(zero_reg, zero_reg, t2);
+    Push(zero_reg, t2);
   } else {
-    MultiPush(t2.bit() | cp.bit() | fp.bit());
+    MultiPush(t2.bit() | cp.bit());
   }
 
   // Link the current handler as the next handler.

src/mips64/macro-assembler-mips64.cc

@@ -3225,11 +3225,10 @@ void MacroAssembler::DebugBreak() {
 void MacroAssembler::PushTryHandler(StackHandler::Kind kind,
                                     int handler_index) {
   // Adjust this code if not the case.
-  STATIC_ASSERT(StackHandlerConstants::kSize == 4 * kPointerSize);
+  STATIC_ASSERT(StackHandlerConstants::kSize == 3 * kPointerSize);
   STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0 * kPointerSize);
   STATIC_ASSERT(StackHandlerConstants::kStateOffset == 1 * kPointerSize);
   STATIC_ASSERT(StackHandlerConstants::kContextOffset == 2 * kPointerSize);
-  STATIC_ASSERT(StackHandlerConstants::kFPOffset == 3 * kPointerSize);
 
   // For the JSEntry handler, we must preserve a0-a3 and s0.
   // a5-a7 are available. We will build up the handler from the bottom by
@@ -3241,15 +3240,14 @@ void MacroAssembler::PushTryHandler(StackHandler::Kind kind,
   li(a5, Operand(CodeObject()), CONSTANT_SIZE);
   li(a6, Operand(state));
 
-  // Push the frame pointer, context, and state.
+  // Push the context and state.
   if (kind == StackHandler::JS_ENTRY) {
-    DCHECK_EQ(static_cast<Smi*>(0), Smi::FromInt(0));
-    // The second zero_reg indicates no context.
-    // The first zero_reg is the NULL frame pointer.
+    DCHECK(Smi::FromInt(0) == 0);
+    // The zero_reg indicates no context.
     // The operands are reversed to match the order of MultiPush/Pop.
-    Push(zero_reg, zero_reg, a6);
+    Push(zero_reg, a6);
   } else {
-    MultiPush(a6.bit() | cp.bit() | fp.bit());
+    MultiPush(a6.bit() | cp.bit());
   }
 
   // Link the current handler as the next handler.