[compiler][backend][x64] Fix gap checking for X64Push codegen

- Removes DCHECKs that will be incorrect when SIMD operands
  are intermixed.
- Reworks the code structure to break out 3 major cases:
  Immediate, MemoryOperand, and LocationOperand.

Bug: v8:9198

Change-Id: I1be426bc450dda0fd670a2483aae9afd2c96ce17
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2673271
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72551}

src/codegen/x64/macro-assembler-x64.cc

@@ -3018,11 +3018,13 @@ void TurboAssembler::AllocateStackSpace(Register bytes_scratch) {
 }
 
 void TurboAssembler::AllocateStackSpace(int bytes) {
+  DCHECK_GE(bytes, 0);
   while (bytes > kStackPageSize) {
     subq(rsp, Immediate(kStackPageSize));
     movb(Operand(rsp, 0), Immediate(0));
     bytes -= kStackPageSize;
   }
+  if (bytes == 0) return;
   subq(rsp, Immediate(bytes));
 }
 #endif

src/codegen/x64/macro-assembler-x64.h

@@ -657,7 +657,11 @@ class V8_EXPORT_PRIVATE TurboAssembler : public TurboAssemblerBase {
   void AllocateStackSpace(int bytes);
 #else
   void AllocateStackSpace(Register bytes) { subq(rsp, bytes); }
-  void AllocateStackSpace(int bytes) { subq(rsp, Immediate(bytes)); }
+  void AllocateStackSpace(int bytes) {
+    DCHECK_GE(bytes, 0);
+    if (bytes == 0) return;
+    subq(rsp, Immediate(bytes));
+  }
 #endif
 
   // Removes current frame and its arguments from the stack preserving the

src/compiler/backend/x64/code-generator-x64.cc

@@ -2264,48 +2264,44 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       break;
     case kX64Push: {
       int stack_decrement = i.InputInt32(0);
-      if (HasAddressingMode(instr)) {
-        // 1 slot values are never padded.
-        DCHECK_EQ(stack_decrement, kSystemPointerSize);
+      int slots = stack_decrement / kSystemPointerSize;
+      // Whenever codegen uses pushq, we need to check if stack_decrement
+      // contains any extra padding and adjust the stack before the pushq.
+      if (HasImmediateInput(instr, 1)) {
+        __ AllocateStackSpace(stack_decrement - kSystemPointerSize);
+        __ pushq(i.InputImmediate(1));
+      } else if (HasAddressingMode(instr)) {
+        __ AllocateStackSpace(stack_decrement - kSystemPointerSize);
         size_t index = 1;
         Operand operand = i.MemoryOperand(&index);
         __ pushq(operand);
-      } else if (HasImmediateInput(instr, 1)) {
-        // 1 slot values are never padded.
-        DCHECK_EQ(stack_decrement, kSystemPointerSize);
-        __ pushq(i.InputImmediate(1));
-      } else if (HasRegisterInput(instr, 1)) {
-        // 1 slot values are never padded.
-        DCHECK_EQ(stack_decrement, kSystemPointerSize);
-        __ pushq(i.InputRegister(1));
-      } else if (instr->InputAt(1)->IsFloatRegister() ||
-                 instr->InputAt(1)->IsDoubleRegister()) {
-        // 1 slot values are never padded.
-        DCHECK_EQ(stack_decrement, kSystemPointerSize);
-        __ AllocateStackSpace(kSystemPointerSize);
-        __ Movsd(Operand(rsp, 0), i.InputDoubleRegister(1));
-      } else if (instr->InputAt(1)->IsSimd128Register()) {
-        // 2 slot values have up to 1 slot of padding.
-        DCHECK_GE(stack_decrement, kSimd128Size);
-        __ AllocateStackSpace(stack_decrement);
-        // TODO(bbudge) Use Movaps when slots are aligned.
-        __ Movups(Operand(rsp, 0), i.InputSimd128Register(1));
-      } else if (instr->InputAt(1)->IsStackSlot() ||
-                 instr->InputAt(1)->IsFloatStackSlot() ||
-                 instr->InputAt(1)->IsDoubleStackSlot()) {
-        // 1 slot values are never padded.
-        DCHECK_EQ(stack_decrement, kSystemPointerSize);
-        __ pushq(i.InputOperand(1));
       } else {
-        DCHECK(instr->InputAt(1)->IsSimd128StackSlot());
-        // 2 slot values have up to 1 slot of padding.
-        DCHECK_GE(stack_decrement, kSimd128Size);
-        // TODO(bbudge) Use Movaps when slots are aligned.
-        __ Movups(kScratchDoubleReg, i.InputOperand(1));
-        __ AllocateStackSpace(stack_decrement);
-        __ Movups(Operand(rsp, 0), kScratchDoubleReg);
+        InstructionOperand* input = instr->InputAt(1);
+        if (input->IsRegister()) {
+          __ AllocateStackSpace(stack_decrement - kSystemPointerSize);
+          __ pushq(i.InputRegister(1));
+        } else if (input->IsFloatRegister() || input->IsDoubleRegister()) {
+          DCHECK_GE(stack_decrement, kSystemPointerSize);
+          __ AllocateStackSpace(stack_decrement);
+          __ Movsd(Operand(rsp, 0), i.InputDoubleRegister(1));
+        } else if (input->IsSimd128Register()) {
+          DCHECK_GE(stack_decrement, kSimd128Size);
+          __ AllocateStackSpace(stack_decrement);
+          // TODO(bbudge) Use Movaps when slots are aligned.
+          __ Movups(Operand(rsp, 0), i.InputSimd128Register(1));
+        } else if (input->IsStackSlot() || input->IsFloatStackSlot() ||
+                   input->IsDoubleStackSlot()) {
+          __ AllocateStackSpace(stack_decrement - kSystemPointerSize);
+          __ pushq(i.InputOperand(1));
+        } else {
+          DCHECK(input->IsSimd128StackSlot());
+          DCHECK_GE(stack_decrement, kSimd128Size);
+          // TODO(bbudge) Use Movaps when slots are aligned.
+          __ Movups(kScratchDoubleReg, i.InputOperand(1));
+          __ AllocateStackSpace(stack_decrement);
+          __ Movups(Operand(rsp, 0), kScratchDoubleReg);
+        }
       }
-      int slots = stack_decrement / kSystemPointerSize;
       frame_access_state()->IncreaseSPDelta(slots);
       unwinding_info_writer_.MaybeIncreaseBaseOffsetAt(__ pc_offset(),
                                                        stack_decrement);