[llvm] r256352 - [Statepoints] Use Indirect operands for spill slots
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Wed Dec 23 15:44:28 PST 2015
Author: reames
Date: Wed Dec 23 17:44:28 2015
New Revision: 256352
URL: http://llvm.org/viewvc/llvm-project?rev=256352&view=rev
Log:
[Statepoints] Use Indirect operands for spill slots
Teach the statepoint lowering code to emit Indirect stackmap entries for spill inserted by StatepointLowering (i.e. SelectionDAG), but Direct stackmap entries for in-IR allocas which represent manual stack slots. This is what the docs call for (http://llvm.org/docs/StackMaps.html#stack-map-format), but we've been emitting both as Direct. This was pointed out recently on the mailing list as a bug. It also blocks http://reviews.llvm.org/D15632 which extends the lowering to handle vector-of-pointers since only Indirect references can encode a variable sized slot.
To implement this, I introduced a new flag on the StackObject class used to maintian information about stack slots. I original considered (and prototyped in http://reviews.llvm.org/D15632), the idea of using the existing isSpillSlot flag, but end up deciding that was a bit too risky and that the cost of adding a new flag was low. Having the new flag will also allow us - in the future - to emit better comments in verbose assembly which indicate where a particular stack spill around a call comes from. (deopt, gc, regalloc).
Differential Revision: http://reviews.llvm.org/D15759
Modified:
llvm/trunk/include/llvm/CodeGen/MachineFrameInfo.h
llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp
llvm/trunk/test/CodeGen/X86/statepoint-stackmap-format.ll
Modified: llvm/trunk/include/llvm/CodeGen/MachineFrameInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineFrameInfo.h?rev=256352&r1=256351&r2=256352&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineFrameInfo.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachineFrameInfo.h Wed Dec 23 17:44:28 2015
@@ -101,6 +101,13 @@ class MachineFrameInfo {
// cannot alias any other memory objects.
bool isSpillSlot;
+ /// If true, this stack slot is used to spill a value (could be deopt
+ /// and/or GC related) over a statepoint. We know that the address of the
+ /// slot can't alias any LLVM IR value. This is very similiar to a Spill
+ /// Slot, but is created by statepoint lowering is SelectionDAG, not the
+ /// register allocator.
+ bool isStatepointSpillSlot;
+
/// If this stack object is originated from an Alloca instruction
/// this value saves the original IR allocation. Can be NULL.
const AllocaInst *Alloca;
@@ -118,7 +125,8 @@ class MachineFrameInfo {
StackObject(uint64_t Sz, unsigned Al, int64_t SP, bool IM,
bool isSS, const AllocaInst *Val, bool A)
: SPOffset(SP), Size(Sz), Alignment(Al), isImmutable(IM),
- isSpillSlot(isSS), Alloca(Val), PreAllocated(false), isAliased(A) {}
+ isSpillSlot(isSS), isStatepointSpillSlot(false), Alloca(Val),
+ PreAllocated(false), isAliased(A) {}
};
/// The alignment of the stack.
@@ -547,6 +555,12 @@ public:
return Objects[ObjectIdx+NumFixedObjects].isSpillSlot;
}
+ bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
+ return Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot;
+ }
+
/// Returns true if the specified index corresponds to a dead object.
bool isDeadObjectIndex(int ObjectIdx) const {
assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
@@ -562,6 +576,13 @@ public:
return Objects[ObjectIdx + NumFixedObjects].Size == 0;
}
+ void markAsStatepointSpillSlotObjectIndex(int ObjectIdx) {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
+ Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot = true;
+ assert(isStatepointSpillSlotObjectIndex(ObjectIdx) && "inconsistent");
+ }
+
/// Create a new statically sized stack object, returning
/// a nonnegative identifier to represent it.
int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSS,
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp?rev=256352&r1=256351&r2=256352&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp Wed Dec 23 17:44:28 2015
@@ -17,6 +17,7 @@
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/FunctionLoweringInfo.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/GCMetadata.h"
#include "llvm/CodeGen/GCStrategy.h"
#include "llvm/CodeGen/SelectionDAG.h"
@@ -95,6 +96,9 @@ StatepointLoweringState::allocateStackSl
SDValue SpillSlot = Builder.DAG.CreateStackTemporary(ValueType);
const unsigned FI = cast<FrameIndexSDNode>(SpillSlot)->getIndex();
+ auto *MFI = Builder.DAG.getMachineFunction().getFrameInfo();
+ MFI->markAsStatepointSpillSlotObjectIndex(FI);
+
Builder.FuncInfo.StatepointStackSlots.push_back(FI);
AllocatedStackSlots.push_back(true);
return SpillSlot;
Modified: llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp?rev=256352&r1=256351&r2=256352&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp (original)
+++ llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp Wed Dec 23 17:44:28 2015
@@ -1094,6 +1094,19 @@ MachineBasicBlock*
TargetLoweringBase::emitPatchPoint(MachineInstr *MI,
MachineBasicBlock *MBB) const {
MachineFunction &MF = *MI->getParent()->getParent();
+ MachineFrameInfo &MFI = *MF.getFrameInfo();
+
+ // We're handling multiple types of operands here:
+ // PATCHPOINT MetaArgs - live-in, read only, direct
+ // STATEPOINT Deopt Spill - live-through, read only, indirect
+ // STATEPOINT Deopt Alloca - live-through, read only, direct
+ // (We're currently conservative and mark the deopt slots read/write in
+ // practice.)
+ // STATEPOINT GC Spill - live-through, read/write, indirect
+ // STATEPOINT GC Alloca - live-through, read/write, direct
+ // The live-in vs live-through is handled already (the live through ones are
+ // all stack slots), but we need to handle the different type of stackmap
+ // operands and memory effects here.
// MI changes inside this loop as we grow operands.
for(unsigned OperIdx = 0; OperIdx != MI->getNumOperands(); ++OperIdx) {
@@ -1109,10 +1122,24 @@ TargetLoweringBase::emitPatchPoint(Machi
// Copy operands before the frame-index.
for (unsigned i = 0; i < OperIdx; ++i)
MIB.addOperand(MI->getOperand(i));
- // Add frame index operands: direct-mem-ref tag, #FI, offset.
- MIB.addImm(StackMaps::DirectMemRefOp);
- MIB.addOperand(MI->getOperand(OperIdx));
- MIB.addImm(0);
+ // Add frame index operands recognized by stackmaps.cpp
+ if (MFI.isStatepointSpillSlotObjectIndex(FI)) {
+ // indirect-mem-ref tag, size, #FI, offset.
+ // Used for spills inserted by StatepointLowering. This codepath is not
+ // used for patchpoints/stackmaps at all, for these spilling is done via
+ // foldMemoryOperand callback only.
+ assert(MI->getOpcode() == TargetOpcode::STATEPOINT && "sanity");
+ MIB.addImm(StackMaps::IndirectMemRefOp);
+ MIB.addImm(MFI.getObjectSize(FI));
+ MIB.addOperand(MI->getOperand(OperIdx));
+ MIB.addImm(0);
+ } else {
+ // direct-mem-ref tag, #FI, offset.
+ // Used by patchpoint, and direct alloca arguments to statepoints
+ MIB.addImm(StackMaps::DirectMemRefOp);
+ MIB.addOperand(MI->getOperand(OperIdx));
+ MIB.addImm(0);
+ }
// Copy the operands after the frame index.
for (unsigned i = OperIdx + 1; i != MI->getNumOperands(); ++i)
MIB.addOperand(MI->getOperand(i));
@@ -1122,7 +1149,6 @@ TargetLoweringBase::emitPatchPoint(Machi
assert(MIB->mayLoad() && "Folded a stackmap use to a non-load!");
// Add a new memory operand for this FI.
- const MachineFrameInfo &MFI = *MF.getFrameInfo();
assert(MFI.getObjectOffset(FI) != -1);
unsigned Flags = MachineMemOperand::MOLoad;
Modified: llvm/trunk/test/CodeGen/X86/statepoint-stackmap-format.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/statepoint-stackmap-format.ll?rev=256352&r1=256351&r2=256352&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/statepoint-stackmap-format.ll (original)
+++ llvm/trunk/test/CodeGen/X86/statepoint-stackmap-format.ll Wed Dec 23 17:44:28 2015
@@ -11,7 +11,7 @@ declare zeroext i1 @return_i1()
define i1 @test(i32 addrspace(1)* %ptr_base, i32 %arg)
gc "statepoint-example" {
-; CHECK-LABEL: test
+; CHECK-LABEL: test:
; Do we see two spills for the local values and the store to the
; alloca?
; CHECK: subq $40, %rsp
@@ -94,18 +94,19 @@ declare i32 addrspace(1)* @llvm.experime
; CHECK-NEXT: .quad 40
; CHECK-NEXT: .quad test_derived_arg
; CHECK-NEXT: .quad 40
+; CHECK-NEXT: .quad test_id
+; CHECK-NEXT: .quad 8
;
; test
;
-; Large Constants
-; Statepoint ID only
-; CHECK: .quad 0
+; Statepoint ID
+; CHECK-NEXT: .quad 0
; Callsites
; Constant arguments
-; CHECK: .long .Ltmp1-test
+; CHECK-NEXT: .long .Ltmp1-test
; CHECK: .short 0
; CHECK: .short 11
; SmallConstant (0)
@@ -123,8 +124,8 @@ declare i32 addrspace(1)* @llvm.experime
; CHECK: .byte 8
; CHECK: .short 0
; CHECK: .long 2
-; Direct Spill Slot [RSP+0]
-; CHECK: .byte 2
+; Indirect Spill Slot [RSP+0]
+; CHECK: .byte 3
; CHECK: .byte 8
; CHECK: .short 7
; CHECK: .long 16
@@ -143,23 +144,23 @@ declare i32 addrspace(1)* @llvm.experime
; CHECK: .byte 8
; CHECK: .short 0
; CHECK: .long 0
-; Direct Spill Slot [RSP+16]
-; CHECK: .byte 2
+; Indirect Spill Slot [RSP+16]
+; CHECK: .byte 3
; CHECK: .byte 8
; CHECK: .short 7
; CHECK: .long 16
-; Direct Spill Slot [RSP+8]
-; CHECK: .byte 2
+; Indirect Spill Slot [RSP+8]
+; CHECK: .byte 3
; CHECK: .byte 8
; CHECK: .short 7
; CHECK: .long 8
-; Direct Spill Slot [RSP+16]
-; CHECK: .byte 2
+; Indirect Spill Slot [RSP+16]
+; CHECK: .byte 3
; CHECK: .byte 8
; CHECK: .short 7
; CHECK: .long 16
-; Direct Spill Slot [RSP+16]
-; CHECK: .byte 2
+; Indirect Spill Slot [RSP+16]
+; CHECK: .byte 3
; CHECK: .byte 8
; CHECK: .short 7
; CHECK: .long 16
@@ -171,15 +172,13 @@ declare i32 addrspace(1)* @llvm.experime
;
; test_derived_arg
-;
-; Large Constants
-; Statepoint ID only
-; CHECK: .quad 0
+; Statepoint ID
+; CHECK-NEXT: .quad 0
; Callsites
; Constant arguments
-; CHECK: .long .Ltmp3-test_derived_arg
+; CHECK-NEXT: .long .Ltmp3-test_derived_arg
; CHECK: .short 0
; CHECK: .short 11
; SmallConstant (0)
@@ -192,8 +191,8 @@ declare i32 addrspace(1)* @llvm.experime
; CHECK: .byte 8
; CHECK: .short 0
; CHECK: .long 2
-; Direct Spill Slot [RSP+0]
-; CHECK: .byte 2
+; Indirect Spill Slot [RSP+0]
+; CHECK: .byte 3
; CHECK: .byte 8
; CHECK: .short 7
; CHECK: .long 16
@@ -212,23 +211,23 @@ declare i32 addrspace(1)* @llvm.experime
; CHECK: .byte 8
; CHECK: .short 0
; CHECK: .long 0
-; Direct Spill Slot [RSP+16]
-; CHECK: .byte 2
+; Indirect Spill Slot [RSP+16]
+; CHECK: .byte 3
; CHECK: .byte 8
; CHECK: .short 7
; CHECK: .long 16
-; Direct Spill Slot [RSP+8]
-; CHECK: .byte 2
+; Indirect Spill Slot [RSP+8]
+; CHECK: .byte 3
; CHECK: .byte 8
; CHECK: .short 7
; CHECK: .long 8
-; Direct Spill Slot [RSP+16]
-; CHECK: .byte 2
+; Indirect Spill Slot [RSP+16]
+; CHECK: .byte 3
; CHECK: .byte 8
; CHECK: .short 7
; CHECK: .long 16
-; Direct Spill Slot [RSP+16]
-; CHECK: .byte 2
+; Indirect Spill Slot [RSP+16]
+; CHECK: .byte 3
; CHECK: .byte 8
; CHECK: .short 7
; CHECK: .long 16
@@ -239,13 +238,12 @@ declare i32 addrspace(1)* @llvm.experime
; CHECK: .align 8
; Records for the test_id function:
-; No large constants
; The Statepoint ID:
-; CHECK: .quad 237
+; CHECK-NEXT: .quad 237
; Instruction Offset
-; CHECK: .long .Ltmp5-test_id
+; CHECK-NEXT: .long .Ltmp5-test_id
; Reserved:
; CHECK: .short 0
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