[turbofan] Support variable size argument popping in TF-generated functions

src/compiler/mips/code-generator-mips.cc

Index: src/compiler/mips/code-generator-mips.cc
diff --git a/src/compiler/mips/code-generator-mips.cc b/src/compiler/mips/code-generator-mips.cc
index 56c35287d39002cdacd29e79d4faeeb6d0457338..6c31a411b60ba98af6482ada57dccda27775fb5e 100644
--- a/src/compiler/mips/code-generator-mips.cc
+++ b/src/compiler/mips/code-generator-mips.cc
@@ -709,7 +709,7 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       break;
     }
     case kArchRet:
-      AssembleReturn();
+      AssembleReturn(instr->InputAt(0));
       break;
     case kArchStackPointer:
       __ mov(i.OutputRegister(), sp);
@@ -1960,8 +1960,7 @@ void CodeGenerator::AssembleConstructFrame() {
   }
 }
 
-
-void CodeGenerator::AssembleReturn() {
+void CodeGenerator::AssembleReturn(InstructionOperand* pop) {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
   int pop_count = static_cast<int>(descriptor->StackParameterCount());
 
@@ -1977,18 +1976,32 @@ void CodeGenerator::AssembleReturn() {
     __ MultiPopFPU(saves_fpu);
   }
 
+  MipsOperandConverter g(this, nullptr);
   if (descriptor->IsCFunctionCall()) {
     AssembleDeconstructFrame();
   } else if (frame_access_state()->has_frame()) {
-    // Canonicalize JSFunction return sites for now.
-    if (return_label_.is_bound()) {
-      __ Branch(&return_label_);
-      return;
+    // Canonicalize JSFunction return sites for now unless they have an variable
+    // number of stack slot pops.
+    if (pop->IsImmediate() && g.ToConstant(pop).ToInt32() == 0) {
+      if (return_label_.is_bound()) {
+        __ Branch(&return_label_);
+        return;
+      } else {
+        __ bind(&return_label_);
+        AssembleDeconstructFrame();
+      }
     } else {
-      __ bind(&return_label_);
       AssembleDeconstructFrame();
     }
   }
+  if (pop->IsImmediate()) {
+    DCHECK_EQ(Constant::kInt32, g.ToConstant(pop).type());
+    pop_count += g.ToConstant(pop).ToInt32();
+  } else {
+    Register pop_reg = g.ToRegister(pop);
+    __ sll(pop_reg, pop_reg, kPointerSizeLog2);
+    __ Addu(sp, sp, Operand(pop_reg));
+  }
   if (pop_count != 0) {
     __ DropAndRet(pop_count);
   } else {