[llvm] r259220 - [WebAssembly] Support frame pointer
Derek Schuff via llvm-commits
llvm-commits at lists.llvm.org
Fri Jan 29 10:37:50 PST 2016
Author: dschuff
Date: Fri Jan 29 12:37:49 2016
New Revision: 259220
URL: http://llvm.org/viewvc/llvm-project?rev=259220&view=rev
Log:
[WebAssembly] Support frame pointer
Add support for frame pointer use in prolog/epilog.
Supports dynamic allocas but not yet over-aligned locals.
Target-independend CG generates SP updates, but we still need to write
back the SP value to memory when necessary.
Modified:
llvm/trunk/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
llvm/trunk/lib/Target/WebAssembly/WebAssemblyInstrInfo.cpp
llvm/trunk/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp
llvm/trunk/test/CodeGen/WebAssembly/userstack.ll
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp?rev=259220&r1=259219&r2=259220&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp Fri Jan 29 12:37:49 2016
@@ -70,6 +70,7 @@ static void adjustStackPointer(unsigned
const TargetInstrInfo* TII,
MachineBasicBlock::iterator InsertPt,
const DebugLoc& DL) {
+ assert((StackSize || !AdjustUp) && "Adjusting up by 0");
auto &MRI = MF.getRegInfo();
unsigned SPReg = MRI.createVirtualRegister(&WebAssembly::I32RegClass);
auto *SPSymbol = MF.createExternalSymbolName("__stack_pointer");
@@ -82,8 +83,8 @@ static void adjustStackPointer(unsigned
auto *LoadMMO = new MachineMemOperand(MachinePointerInfo(),
MachineMemOperand::MOLoad, 4, 4);
BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::LOAD_I32), SPReg)
- .addImm(0)
- .addReg(SPReg)
+ .addImm(0) // offset
+ .addReg(SPReg) // addr
.addImm(2) // p2align
.addMemOperand(LoadMMO);
// Add/Subtract the frame size
@@ -116,6 +117,9 @@ void WebAssemblyFrameLowering::eliminate
unsigned Opc = I->getOpcode();
bool IsDestroy = Opc == TII->getCallFrameDestroyOpcode();
unsigned Amount = I->getOperand(0).getImm();
+ // TODO(dschuff): After we switch varargs to passing an explicit pointer
+ // rather than using an implicit call frame, assert here that Amount is 0
+ // and remove adjustStackPointer altogether.
if (Amount)
adjustStackPointer(Amount, IsDestroy, MF, MBB,
TII, I, DL);
@@ -128,23 +132,76 @@ void WebAssemblyFrameLowering::emitProlo
auto *MFI = MF.getFrameInfo();
assert(MFI->getCalleeSavedInfo().empty() &&
"WebAssembly should not have callee-saved registers");
- assert(!hasFP(MF) && "Functions needing frame pointers not yet supported");
+
uint64_t StackSize = MFI->getStackSize();
- if (!StackSize && (!MFI->adjustsStack() || MFI->getMaxCallFrameSize() == 0))
+ if (!StackSize && !MFI->adjustsStack())
return;
const auto *TII = MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
+ auto &MRI = MF.getRegInfo();
auto InsertPt = MBB.begin();
DebugLoc DL;
- adjustStackPointer(StackSize, false, MF, MBB, TII, InsertPt, DL);
+ unsigned SPReg = MRI.createVirtualRegister(&WebAssembly::I32RegClass);
+ auto *SPSymbol = MF.createExternalSymbolName("__stack_pointer");
+ BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), SPReg)
+ .addExternalSymbol(SPSymbol);
+ // This MachinePointerInfo should reference __stack_pointer as well but
+ // doesn't because MachinePointerInfo() takes a GV which we don't have for
+ // __stack_pointer. TODO: check if PseudoSourceValue::ExternalSymbolCallEntry
+ // is appropriate instead. (likewise for EmitEpologue below)
+ auto *LoadMMO = new MachineMemOperand(MachinePointerInfo(),
+ MachineMemOperand::MOLoad, 4, 4);
+ // Load the SP value.
+ BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::LOAD_I32),
+ StackSize ? SPReg : WebAssembly::SP32)
+ .addImm(0) // offset
+ .addReg(SPReg) // addr
+ .addImm(2) // p2align
+ .addMemOperand(LoadMMO);
+
+ unsigned OffsetReg = 0;
+ if (StackSize) {
+ // Subtract the frame size
+ OffsetReg = MRI.createVirtualRegister(&WebAssembly::I32RegClass);
+ BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), OffsetReg)
+ .addImm(StackSize);
+ BuildMI(MBB, InsertPt, DL,
+ TII->get(WebAssembly::SUB_I32),
+ WebAssembly::SP32)
+ .addReg(SPReg)
+ .addReg(OffsetReg);
+ }
+ if (hasFP(MF)) {
+ // Unlike most conventional targets (where FP points to the saved FP),
+ // FP points to the bottom of the fixed-size locals, so we can use positive
+ // offsets in load/store instructions.
+ BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::COPY_LOCAL_I32),
+ WebAssembly::FP32)
+ .addReg(WebAssembly::SP32);
+ }
+ if (StackSize) {
+ assert(OffsetReg);
+ // The SP32 register now has the new stacktop. Also write it back to memory.
+ BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), OffsetReg)
+ .addExternalSymbol(SPSymbol);
+ auto *MMO = new MachineMemOperand(MachinePointerInfo(),
+ MachineMemOperand::MOStore, 4, 4);
+ BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::STORE_I32), WebAssembly::SP32)
+ .addImm(0)
+ .addReg(OffsetReg)
+ .addImm(2) // p2align
+ .addReg(WebAssembly::SP32)
+ .addMemOperand(MMO);
+ }
}
void WebAssemblyFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
- uint64_t StackSize = MF.getFrameInfo()->getStackSize();
- if (!StackSize)
+ auto *MFI = MF.getFrameInfo();
+ uint64_t StackSize = MFI->getStackSize();
+ if (!StackSize && !MFI->adjustsStack())
return;
const auto *TII = MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
auto &MRI = MF.getRegInfo();
@@ -156,14 +213,17 @@ void WebAssemblyFrameLowering::emitEpilo
DL = InsertPt->getDebugLoc();
}
- // Restore the stack pointer. Without FP its value is just SP32 - stacksize
- BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), OffsetReg)
- .addImm(StackSize);
+ // Restore the stack pointer. If we had fixed-size locals, add the offset
+ // subtracted in the prolog.
+ if (StackSize) {
+ BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), OffsetReg)
+ .addImm(StackSize);
+ BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::ADD_I32), WebAssembly::SP32)
+ .addReg(hasFP(MF) ? WebAssembly::FP32 : WebAssembly::SP32)
+ .addReg(OffsetReg);
+ }
+
auto *SPSymbol = MF.createExternalSymbolName("__stack_pointer");
- // TODO: Fold this add into the const offset field of the store.
- BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::ADD_I32), WebAssembly::SP32)
- .addReg(WebAssembly::SP32)
- .addReg(OffsetReg);
// Re-use OffsetReg to hold the address of the stacktop
BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), OffsetReg)
.addExternalSymbol(SPSymbol);
@@ -173,6 +233,6 @@ void WebAssemblyFrameLowering::emitEpilo
.addImm(0)
.addReg(OffsetReg)
.addImm(2) // p2align
- .addReg(WebAssembly::SP32)
+ .addReg((!StackSize && hasFP(MF)) ? WebAssembly::FP32 : WebAssembly::SP32)
.addMemOperand(MMO);
}
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyInstrInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyInstrInfo.cpp?rev=259220&r1=259219&r2=259220&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyInstrInfo.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyInstrInfo.cpp Fri Jan 29 12:37:49 2016
@@ -58,7 +58,7 @@ void WebAssemblyInstrInfo::copyPhysReg(M
const TargetRegisterClass *RC =
TargetRegisterInfo::isVirtualRegister(DestReg)
? MRI.getRegClass(DestReg)
- : MRI.getTargetRegisterInfo()->getMinimalPhysRegClass(SrcReg);
+ : MRI.getTargetRegisterInfo()->getMinimalPhysRegClass(DestReg);
unsigned CopyLocalOpcode;
if (RC == &WebAssembly::I32RegClass)
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp?rev=259220&r1=259219&r2=259220&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp Fri Jan 29 12:37:49 2016
@@ -108,10 +108,15 @@ bool WebAssemblyRegNumbering::runOnMachi
}
}
// Allocate locals for used physical registers
- if (FrameInfo.getStackSize() > 0) {
+ if (FrameInfo.getStackSize() > 0 || FrameInfo.adjustsStack()) {
DEBUG(dbgs() << "PReg SP " << CurReg << "\n");
MFI.addPReg(WebAssembly::SP32, CurReg++);
}
+ bool HasFP = MF.getSubtarget().getFrameLowering()->hasFP(MF);
+ if (HasFP) {
+ DEBUG(dbgs() << "PReg FP " << CurReg << "\n");
+ MFI.addPReg(WebAssembly::FP32, CurReg++);
+ }
return true;
}
Modified: llvm/trunk/test/CodeGen/WebAssembly/userstack.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/userstack.ll?rev=259220&r1=259219&r2=259220&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/userstack.ll (original)
+++ llvm/trunk/test/CodeGen/WebAssembly/userstack.ll Fri Jan 29 12:37:49 2016
@@ -119,9 +119,36 @@ define void @allocarray_inbounds() {
; CHECK-LABEL: dynamic_alloca:
define void @dynamic_alloca(i32 %alloc) {
- ; TODO: Support frame pointers
- ;%r = alloca i32, i32 %alloc
- ;store i32 0, i32* %r
+ ; CHECK: i32.const [[L0:.+]]=, __stack_pointer
+ ; CHECK-NEXT: i32.load [[SP:.+]]=, 0([[L0]])
+ ; CHECK-NEXT: copy_local [[FP:.+]]=, [[SP]]
+ ; Target independent codegen bumps the stack pointer
+ ; FIXME: we need to write the value back to memory
+ %r = alloca i32, i32 %alloc
+ ; Target-independent codegen also calculates the store addr
+ store i32 0, i32* %r
+ ; CHECK: i32.const [[L3:.+]]=, __stack_pointer
+ ; CHECK-NEXT: i32.store [[SP]]=, 0([[L3]]), [[FP]]
+ ret void
+}
+
+
+; CHECK-LABEL: dynamic_static_alloca:
+define void @dynamic_static_alloca(i32 %alloc) {
+ ; CHECK: i32.const [[L0:.+]]=, __stack_pointer
+ ; CHECK-NEXT: i32.load [[L0]]=, 0([[L0]])
+ ; CHECK-NEXT: i32.const [[L2:.+]]=, 16
+ ; CHECK-NEXT: i32.sub [[SP:.+]]=, [[L0]], [[L2]]
+ ; CHECK-NEXT: copy_local [[FP:.+]]=, [[SP]]
+ ; CHECK-NEXT: i32.const [[L3:.+]]=, __stack_pointer
+ ; CHECK-NEXT: i32.store {{.*}}=, 0([[L3]]), [[SP]]
+ %r1 = alloca i32
+ %r = alloca i32, i32 %alloc
+ store i32 0, i32* %r
+ ; CHECK: i32.const [[L3:.+]]=, 16
+ ; CHECK: i32.add [[SP]]=, [[FP]], [[L3]]
+ ; CHECK: i32.const [[L4:.+]]=, __stack_pointer
+ ; CHECK-NEXT: i32.store [[SP]]=, 0([[L4]]), [[SP]]
ret void
}
; TODO: test aligned alloc
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