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Unified Diff: src/compiler/frame.h

Issue 1261923007: [turbofan] Unify referencing of stack slots (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@master
Patch Set: Review feedback Created 5 years, 4 months ago
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Index: src/compiler/frame.h
diff --git a/src/compiler/frame.h b/src/compiler/frame.h
index f901b1e2b3402bc662023b1618cefa4702cc7cc5..aa823b6ba8ad0f885c68ed6dfe91f460a48e11c2 100644
--- a/src/compiler/frame.h
+++ b/src/compiler/frame.h
@@ -6,26 +6,93 @@
#define V8_COMPILER_FRAME_H_
#include "src/bit-vector.h"
+#include "src/frames.h"
namespace v8 {
namespace internal {
namespace compiler {
-// Collects the spill slot requirements and the allocated general and double
-// registers for a compiled function. Frames are usually populated by the
-// register allocator and are used by Linkage to generate code for the prologue
-// and epilogue to compiled code.
+// Collects the spill slot and other frame slot requirements for a compiled
+// function. Frames are usually populated by the register allocator and are used
+// by Linkage to generate code for the prologue and epilogue to compiled code.
+//
+// Frames are divided up into three regions. The first is the fixed header,
+// which always has a constant size and can be predicted before code generation
+// begins depending on the type of code being generated. The second is the
+// region for spill slots, which is immediately below the fixed header and grows
+// as the register allocator needs to spill to the stack and asks the frame for
+// more space. The third region, which contains the callee-saved registers must
+// be reserved after register allocation, since its size can only be precisely
+// determined after register allocation once the number of used callee-saved
+// register is certain.
+//
+// Every pointer in a frame has a slot id. On 32-bit platforms, doubles consume
+// two slots.
+//
+// Stack slot indices >= 0 access the callee stack with slot 0 corresponding to
+// the callee's saved return address and 1 corresponding to the saved frame
+// pointer. Some frames have additional information stored in the fixed header,
+// for example JSFunctions store the function context and marker in the fixed
+// header, with slot index 2 corresponding to the current function context and 3
+// corresponding to the frame marker/JSFunction. The frame region immediately
+// below the fixed header contains spill slots starting a 4 for JsFunctions. The
+// callee-saved frame region below that starts at 4+spilled_slot_count. Callee
+// stack slots corresponding to parameters are accessible through negative slot
+// ids.
+//
+// Every slot of a caller or callee frame is accessible by the register
+// allocator and gap resolver with a SpillSlotOperand containing its
+// corresponding slot id.
+//
+// Below an example JSFunction Frame with slot ids, frame regions and contents:
+//
+// slot JS frame
+// +-----------------+----------------------------
+// -n-1 | parameter 0 | ^
+// |- - - - - - - - -| |
+// -n | | Caller
+// ... | ... | frame slots
+// -2 | parameter n-1 | (slot < 0)
+// |- - - - - - - - -| |
+// -1 | parameter n | v
+// -----+-----------------+----------------------------
+// 0 | return addr | ^ ^
+// |- - - - - - - - -| | |
+// 1 | saved frame ptr | Fixed |
+// |- - - - - - - - -| Header <-- frame ptr |
+// 2 | Context | | |
+// |- - - - - - - - -| | |
+// 3 |JSFunction/Marker| v |
+// +-----------------+---- |
+// 4 | spill 1 | ^ Callee
+// |- - - - - - - - -| | frame slots
+// ... | ... | Spill slots (slot >= 0)
+// |- - - - - - - - -| | |
+// m+4 | spill m | v |
+// +-----------------+---- |
+// m+5 | callee-saved 1 | ^ |
+// |- - - - - - - - -| | |
+// | ... | Callee-saved |
+// |- - - - - - - - -| | |
+// m+r+4 | callee-saved r | v v
+// -----+-----------------+----- <-- stack ptr ---------
+//
class Frame : public ZoneObject {
public:
- Frame()
- : register_save_area_size_(0),
- spill_slot_count_(0),
- osr_stack_slot_count_(0),
- allocated_registers_(NULL),
- allocated_double_registers_(NULL),
- pc_on_stack_(true) {}
+ explicit Frame(int fixed_frame_size_in_slots);
- inline int GetSpillSlotCount() { return spill_slot_count_; }
+ inline int GetTotalFrameSlotCount() { return frame_slot_count_; }
+
+ inline int GetSavedCalleeRegisterSlotCount() {
+ return spilled_callee_register_slot_count_;
+ }
+ inline int GetSpillSlotCount() { return stack_slot_count_; }
+
+ inline void SetElidedFrameSizeInSlots(int slots) {
+ DCHECK_EQ(0, spilled_callee_register_slot_count_);
+ DCHECK_EQ(0, stack_slot_count_);
+ frame_slot_count_ = slots;
+ }
void SetAllocatedRegisters(BitVector* regs) {
DCHECK(allocated_registers_ == NULL);
@@ -41,48 +108,52 @@ class Frame : public ZoneObject {
return !allocated_double_registers_->IsEmpty();
}
- void SetRegisterSaveAreaSize(int size) {
- DCHECK(IsAligned(size, kPointerSize));
- register_save_area_size_ = size;
+ int AlignSavedCalleeRegisterSlots() {
+ DCHECK_EQ(0, spilled_callee_register_slot_count_);
+ int frame_slot_count_before = frame_slot_count_;
+ frame_slot_count_ = RoundUp(frame_slot_count_, 2);
+ return frame_slot_count_before - frame_slot_count_;
}
- int GetRegisterSaveAreaSize() { return register_save_area_size_; }
+ void AllocateSavedCalleeRegisterSlots(int count) {
+ frame_slot_count_ += count;
+ spilled_callee_register_slot_count_ += count;
+ }
- // OSR stack slots, including locals and expression stack slots.
- void SetOsrStackSlotCount(int slots) {
- DCHECK(slots >= 0);
- osr_stack_slot_count_ = slots;
+ int AllocateSpillSlot(int width) {
+ DCHECK_EQ(0, spilled_callee_register_slot_count_);
+ int frame_slot_count_before = frame_slot_count_;
+ int slot = AllocateAlignedFrameSlot(width);
+ stack_slot_count_ += (frame_slot_count_ - frame_slot_count_before);
+ return slot;
}
- int GetOsrStackSlotCount() { return osr_stack_slot_count_; }
+ int ReserveSpillSlots(size_t slot_count) {
+ DCHECK_EQ(0, spilled_callee_register_slot_count_);
+ DCHECK_EQ(0, stack_slot_count_);
+ stack_slot_count_ += static_cast<int>(slot_count);
+ frame_slot_count_ += static_cast<int>(slot_count);
+ return frame_slot_count_ - 1;
+ }
- int AllocateSpillSlot(int width) {
+ private:
+ int AllocateAlignedFrameSlot(int width) {
DCHECK(width == 4 || width == 8);
// Skip one slot if necessary.
if (width > kPointerSize) {
DCHECK(width == kPointerSize * 2);
- spill_slot_count_++;
- spill_slot_count_ |= 1;
+ frame_slot_count_++;
+ frame_slot_count_ |= 1;
}
- return spill_slot_count_++;
- }
-
- void ReserveSpillSlots(size_t slot_count) {
- DCHECK_EQ(0, spill_slot_count_); // can only reserve before allocation.
- spill_slot_count_ = static_cast<int>(slot_count);
+ return frame_slot_count_++;
}
- void SetPCOnStack(bool val) { pc_on_stack_ = val; }
-
- int PCOnStackSize() { return pc_on_stack_ ? kRegisterSize : 0; }
-
private:
- int register_save_area_size_;
- int spill_slot_count_;
- int osr_stack_slot_count_;
+ int frame_slot_count_;
+ int spilled_callee_register_slot_count_;
+ int stack_slot_count_;
BitVector* allocated_registers_;
BitVector* allocated_double_registers_;
- bool pc_on_stack_;
DISALLOW_COPY_AND_ASSIGN(Frame);
};
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