[X86][VARARG] Assign MMO earlier to avoid prolog insert point been sunk across VASTART_SAVE_XMM_REGS

phoebewang · tstellar · commit 19b8368225dc · 2021-11-23T20:15:38.000-08:00
The changes in D80163 defered the assignment of MachineMemOperand (MMO) until the X86ExpandPseudo pass. This will result in crash due to prolog insert point been sunk across the pseudo instruction VASTART_SAVE_XMM_REGS. Moving the assignment to the creation of the node can avoid the problem. Reviewed By: rnk Differential Revision: https://reviews.llvm.org/D112859
diff --git a/llvm/lib/Target/X86/X86ExpandPseudo.cpp b/llvm/lib/Target/X86/X86ExpandPseudo.cpp
@@ -657,35 +657,24 @@ void X86ExpandPseudo::ExpandVastartSaveXmmRegs(
                   EntryBlk->end());
   TailBlk->transferSuccessorsAndUpdatePHIs(EntryBlk);
 
-  int64_t FrameIndex = VAStartPseudoInstr->getOperand(1).getImm();
-  Register BaseReg;
-  uint64_t FrameOffset =
-      X86FL->getFrameIndexReference(*Func, FrameIndex, BaseReg).getFixed();
-  uint64_t VarArgsRegsOffset = VAStartPseudoInstr->getOperand(2).getImm();
+  uint64_t FrameOffset = VAStartPseudoInstr->getOperand(4).getImm();
+  uint64_t VarArgsRegsOffset = VAStartPseudoInstr->getOperand(6).getImm();
 
   // TODO: add support for YMM and ZMM here.
   unsigned MOVOpc = STI->hasAVX() ? X86::VMOVAPSmr : X86::MOVAPSmr;
 
   // In the XMM save block, save all the XMM argument registers.
-  for (int64_t OpndIdx = 3, RegIdx = 0;
+  for (int64_t OpndIdx = 7, RegIdx = 0;
        OpndIdx < VAStartPseudoInstr->getNumOperands() - 1;
        OpndIdx++, RegIdx++) {
-
-    int64_t Offset = FrameOffset + VarArgsRegsOffset + RegIdx * 16;
-
-    MachineMemOperand *MMO = Func->getMachineMemOperand(
-        MachinePointerInfo::getFixedStack(*Func, FrameIndex, Offset),
-        MachineMemOperand::MOStore,
-        /*Size=*/16, Align(16));
-
-    BuildMI(GuardedRegsBlk, DL, TII->get(MOVOpc))
-        .addReg(BaseReg)
-        .addImm(/*Scale=*/1)
-        .addReg(/*IndexReg=*/0)
-        .addImm(/*Disp=*/Offset)
-        .addReg(/*Segment=*/0)
-        .addReg(VAStartPseudoInstr->getOperand(OpndIdx).getReg())
-        .addMemOperand(MMO);
+    auto NewMI = BuildMI(GuardedRegsBlk, DL, TII->get(MOVOpc));
+    for (int i = 0; i < X86::AddrNumOperands; ++i) {
+      if (i == X86::AddrDisp)
+        NewMI.addImm(FrameOffset + VarArgsRegsOffset + RegIdx * 16);
+      else
+        NewMI.add(VAStartPseudoInstr->getOperand(i + 1));
+    }
+    NewMI.addReg(VAStartPseudoInstr->getOperand(OpndIdx).getReg());
     assert(Register::isPhysicalRegister(
         VAStartPseudoInstr->getOperand(OpndIdx).getReg()));
   }
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -3533,13 +3533,19 @@ void VarArgsLoweringHelper::createVarArgAreaAndStoreRegisters(
       SmallVector<SDValue, 12> SaveXMMOps;
       SaveXMMOps.push_back(Chain);
       SaveXMMOps.push_back(ALVal);
-      SaveXMMOps.push_back(
-          DAG.getTargetConstant(FuncInfo->getRegSaveFrameIndex(), DL, MVT::i32));
+      SaveXMMOps.push_back(RSFIN);
       SaveXMMOps.push_back(
           DAG.getTargetConstant(FuncInfo->getVarArgsFPOffset(), DL, MVT::i32));
       llvm::append_range(SaveXMMOps, LiveXMMRegs);
-      MemOps.push_back(DAG.getNode(X86ISD::VASTART_SAVE_XMM_REGS, DL,
-                                   MVT::Other, SaveXMMOps));
+      MachineMemOperand *StoreMMO =
+          DAG.getMachineFunction().getMachineMemOperand(
+              MachinePointerInfo::getFixedStack(
+                  DAG.getMachineFunction(), FuncInfo->getRegSaveFrameIndex(),
+                  Offset),
+              MachineMemOperand::MOStore, 128, Align(16));
+      MemOps.push_back(DAG.getMemIntrinsicNode(X86ISD::VASTART_SAVE_XMM_REGS,
+                                               DL, DAG.getVTList(MVT::Other),
+                                               SaveXMMOps, MVT::i8, StoreMMO));
     }
 
     if (!MemOps.empty())
diff --git a/llvm/lib/Target/X86/X86ISelLowering.h b/llvm/lib/Target/X86/X86ISelLowering.h
@@ -627,10 +627,6 @@ namespace llvm {
     // packed single precision.
     DPBF16PS,
 
-    // Save xmm argument registers to the stack, according to %al. An operator
-    // is needed so that this can be expanded with control flow.
-    VASTART_SAVE_XMM_REGS,
-
     // Windows's _chkstk call to do stack probing.
     WIN_ALLOCA,
 
@@ -848,6 +844,10 @@ namespace llvm {
     AESENCWIDE256KL,
     AESDECWIDE256KL,
 
+    // Save xmm argument registers to the stack, according to %al. An operator
+    // is needed so that this can be expanded with control flow.
+    VASTART_SAVE_XMM_REGS,
+
     // WARNING: Do not add anything in the end unless you want the node to
     // have memop! In fact, starting from FIRST_TARGET_MEMORY_OPCODE all
     // opcodes will be thought as target memory ops!
diff --git a/llvm/lib/Target/X86/X86InstrCompiler.td b/llvm/lib/Target/X86/X86InstrCompiler.td
@@ -69,16 +69,12 @@ def : Pat<(X86callseq_start timm:$amt1, timm:$amt2),
 let SchedRW = [WriteSystem] in {
 
 // x86-64 va_start lowering magic.
-let hasSideEffects = 1, Defs = [EFLAGS] in {
+let hasSideEffects = 1, mayStore = 1, Defs = [EFLAGS] in {
 def VASTART_SAVE_XMM_REGS : I<0, Pseudo,
                               (outs),
-                              (ins GR8:$al,
-                                   i32imm:$regsavefi, i32imm:$offset,
-                                   variable_ops),
-                              "#VASTART_SAVE_XMM_REGS $al, $regsavefi, $offset",
-                              [(X86vastart_save_xmm_regs GR8:$al,
-                                                         timm:$regsavefi,
-                                                         timm:$offset),
+                              (ins GR8:$al, i8mem:$regsavefi, variable_ops),
+                              "#VASTART_SAVE_XMM_REGS $al, $regsavefi",
+                              [(X86vastart_save_xmm_regs GR8:$al, addr:$regsavefi),
                                (implicit EFLAGS)]>;
 }
 
diff --git a/llvm/lib/Target/X86/X86InstrInfo.td b/llvm/lib/Target/X86/X86InstrInfo.td
@@ -91,8 +91,7 @@ def SDT_X86Call   : SDTypeProfile<0, -1, [SDTCisVT<0, iPTR>]>;
 def SDT_X86NtBrind : SDTypeProfile<0, -1, [SDTCisVT<0, iPTR>]>;
 
 def SDT_X86VASTART_SAVE_XMM_REGS : SDTypeProfile<0, -1, [SDTCisVT<0, i8>,
-                                                         SDTCisVT<1, iPTR>,
-                                                         SDTCisVT<2, iPTR>]>;
+                                                         SDTCisPtrTy<1>]>;
 
 def SDT_X86VAARG : SDTypeProfile<1, -1, [SDTCisPtrTy<0>,
                                          SDTCisPtrTy<1>,
@@ -184,7 +183,7 @@ def X86iret : SDNode<"X86ISD::IRET", SDTX86Ret,
 def X86vastart_save_xmm_regs :
                  SDNode<"X86ISD::VASTART_SAVE_XMM_REGS",
                         SDT_X86VASTART_SAVE_XMM_REGS,
-                        [SDNPHasChain, SDNPVariadic]>;
+                        [SDNPHasChain, SDNPMayStore, SDNPMemOperand, SDNPVariadic]>;
 def X86vaarg64 :
                  SDNode<"X86ISD::VAARG_64", SDT_X86VAARG,
                         [SDNPHasChain, SDNPMayLoad, SDNPMayStore,
diff --git a/llvm/test/CodeGen/X86/vaargs-prolog-insert.ll b/llvm/test/CodeGen/X86/vaargs-prolog-insert.ll
@@ -5,6 +5,7 @@
 define void @reduce(i32, i32, i32, i32, i32, i32, ...) nounwind {
 ; CHECK-LABEL: reduce:
 ; CHECK:       # %bb.0:
+; CHECK-NEXT:    subq $56, %rsp
 ; CHECK-NEXT:    testb %al, %al
 ; CHECK-NEXT:    je .LBB0_4
 ; CHECK-NEXT:  # %bb.3:
@@ -21,15 +22,14 @@ define void @reduce(i32, i32, i32, i32, i32, i32, ...) nounwind {
 ; CHECK-NEXT:    testb %al, %al
 ; CHECK-NEXT:    jne .LBB0_2
 ; CHECK-NEXT:  # %bb.1:
-; CHECK-NEXT:    subq $56, %rsp
 ; CHECK-NEXT:    leaq -{{[0-9]+}}(%rsp), %rax
 ; CHECK-NEXT:    movq %rax, 16
 ; CHECK-NEXT:    leaq {{[0-9]+}}(%rsp), %rax
 ; CHECK-NEXT:    movq %rax, 8
 ; CHECK-NEXT:    movl $48, 4
 ; CHECK-NEXT:    movl $48, 0
-; CHECK-NEXT:    addq $56, %rsp
 ; CHECK-NEXT:  .LBB0_2:
+; CHECK-NEXT:    addq $56, %rsp
 ; CHECK-NEXT:    retq
   br i1 undef, label %8, label %7
 
