[mips,mips64] Fix sp and fp offsets for INTERNAL frames

https://crrev.com/c/1075047 introduced a bug on mips/mips64 in which
sp and fp offsets were set incorrectly for INTERNAL frames.

Bug: v8:6666,chromium:847728,chromium:847568
Change-Id: I9a48d30a82f10a4af50f1ed4dc1d77e8defbdd77
Reviewed-on: https://chromium-review.googlesource.com/1078109
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53434}

src/mips/macro-assembler-mips.cc

@@ -4811,14 +4811,8 @@ void TurboAssembler::StubPrologue(StackFrame::Type type) {
 void TurboAssembler::Prologue() { PushStandardFrame(a1); }
 
 void TurboAssembler::EnterFrame(StackFrame::Type type) {
-  int stack_offset, fp_offset;
-  if (type == StackFrame::INTERNAL) {
-    stack_offset = -4 * kPointerSize;
-    fp_offset = 2 * kPointerSize;
-  } else {
-    stack_offset = -3 * kPointerSize;
-    fp_offset = 1 * kPointerSize;
-  }
+  int stack_offset = -3 * kPointerSize;
+  const int fp_offset = 1 * kPointerSize;
   addiu(sp, sp, stack_offset);
   stack_offset = -stack_offset - kPointerSize;
   sw(ra, MemOperand(sp, stack_offset));
@@ -4827,12 +4821,8 @@ void TurboAssembler::EnterFrame(StackFrame::Type type) {
   stack_offset -= kPointerSize;
   li(t9, Operand(StackFrame::TypeToMarker(type)));
   sw(t9, MemOperand(sp, stack_offset));
-  if (type == StackFrame::INTERNAL) {
-    DCHECK_EQ(stack_offset, kPointerSize);
-  } else {
-    DCHECK_EQ(stack_offset, 0);
-  }
   // Adjust FP to point to saved FP.
+  DCHECK_EQ(stack_offset, 0);
   Addu(fp, sp, Operand(fp_offset));
 }
 

src/mips64/macro-assembler-mips64.cc

@@ -5131,14 +5131,8 @@ void TurboAssembler::StubPrologue(StackFrame::Type type) {
 void TurboAssembler::Prologue() { PushStandardFrame(a1); }
 
 void TurboAssembler::EnterFrame(StackFrame::Type type) {
-  int stack_offset, fp_offset;
-  if (type == StackFrame::INTERNAL) {
-    stack_offset = -4 * kPointerSize;
-    fp_offset = 2 * kPointerSize;
-  } else {
-    stack_offset = -3 * kPointerSize;
-    fp_offset = 1 * kPointerSize;
-  }
+  int stack_offset = -3 * kPointerSize;
+  const int fp_offset = 1 * kPointerSize;
   daddiu(sp, sp, stack_offset);
   stack_offset = -stack_offset - kPointerSize;
   Sd(ra, MemOperand(sp, stack_offset));
@@ -5147,12 +5141,8 @@ void TurboAssembler::EnterFrame(StackFrame::Type type) {
   stack_offset -= kPointerSize;
   li(t9, Operand(StackFrame::TypeToMarker(type)));
   Sd(t9, MemOperand(sp, stack_offset));
-  if (type == StackFrame::INTERNAL) {
-    DCHECK_EQ(stack_offset, kPointerSize);
-  } else {
-    DCHECK_EQ(stack_offset, 0);
-  }
   // Adjust FP to point to saved FP.
+  DCHECK_EQ(stack_offset, 0);
   Daddu(fp, sp, Operand(fp_offset));
 }