commit 256a16d0314c78b0ee3612e01d0cafbf6c83de7b
author Tim Northover <tnorthover@apple.com> Mon Dec 17 17:25:53 2018 +0000
committer Tim Northover <tnorthover@apple.com> Mon Dec 17 17:25:53 2018 +0000
tree ac50144a309aa5c7f1387e827ab9c582c9be4055
parent 2d6833c9c9e447e5a0a5fa0b0fa9db18b3dd8111

FastIsel: take care to update iterators when removing instructions.

We keep a few iterators into the basic block we're selecting while
performing FastISel. Usually this is fine, but occasionally code wants
to remove already-emitted instructions. When this happens we have to be
careful to update those iterators so they're not pointint at dangling
memory.

llvm-svn: 349365

llvm/lib/CodeGen/SelectionDAG/FastISel.cpp

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index d5f066c2..a9a3c44 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -547,6 +547,15 @@
   assert(I.isValid() && E.isValid() && std::distance(I, E) > 0 &&
          "Invalid iterator!");
   while (I != E) {
+    if (LastFlushPoint == I)
+      LastFlushPoint = E;
+    if (SavedInsertPt == I)
+      SavedInsertPt = E;
+    if (EmitStartPt == I)
+      EmitStartPt = E.isValid() ? &*E : nullptr;
+    if (LastLocalValue == I)
+      LastLocalValue = E.isValid() ? &*E : nullptr;
+
     MachineInstr *Dead = &*I;
     ++I;
     Dead->eraseFromParent();

llvm/lib/Target/AArch64/AArch64FastISel.cpp

diff --git a/llvm/lib/Target/AArch64/AArch64FastISel.cpp b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
index dfc08a1..7a7b0dd 100644
--- a/llvm/lib/Target/AArch64/AArch64FastISel.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
@@ -2016,8 +2016,9 @@
       if (RetVT == MVT::i64 && VT <= MVT::i32) {
         if (WantZExt) {
           // Delete the last emitted instruction from emitLoad (SUBREG_TO_REG).
-          std::prev(FuncInfo.InsertPt)->eraseFromParent();
-          ResultReg = std::prev(FuncInfo.InsertPt)->getOperand(0).getReg();
+          MachineBasicBlock::iterator I(std::prev(FuncInfo.InsertPt));
+          ResultReg = std::prev(I)->getOperand(0).getReg();
+          removeDeadCode(I, std::next(I));
         } else
           ResultReg = fastEmitInst_extractsubreg(MVT::i32, ResultReg,
                                                  /*IsKill=*/true,
@@ -2038,7 +2039,8 @@
           break;
         }
       }
-      MI->eraseFromParent();
+      MachineBasicBlock::iterator I(MI);
+      removeDeadCode(I, std::next(I));
       MI = nullptr;
       if (Reg)
         MI = MRI.getUniqueVRegDef(Reg);
@@ -4508,7 +4510,8 @@
             MI->getOperand(1).getSubReg() == AArch64::sub_32) &&
            "Expected copy instruction");
     Reg = MI->getOperand(1).getReg();
-    MI->eraseFromParent();
+    MachineBasicBlock::iterator I(MI);
+    removeDeadCode(I, std::next(I));
   }
   updateValueMap(I, Reg);
   return true;

llvm/lib/Target/ARM/ARMFastISel.cpp

diff --git a/llvm/lib/Target/ARM/ARMFastISel.cpp b/llvm/lib/Target/ARM/ARMFastISel.cpp
index fd3d10a..a50abfd 100644
--- a/llvm/lib/Target/ARM/ARMFastISel.cpp
+++ b/llvm/lib/Target/ARM/ARMFastISel.cpp
@@ -2951,7 +2951,8 @@
   unsigned ResultReg = MI->getOperand(0).getReg();
   if (!ARMEmitLoad(VT, ResultReg, Addr, LI->getAlignment(), isZExt, false))
     return false;
-  MI->eraseFromParent();
+  MachineBasicBlock::iterator I(MI);
+  removeDeadCode(I, std::next(I));
   return true;
 }
 

llvm/lib/Target/PowerPC/PPCFastISel.cpp

diff --git a/llvm/lib/Target/PowerPC/PPCFastISel.cpp b/llvm/lib/Target/PowerPC/PPCFastISel.cpp
index 6681698..aa55ac1 100644
--- a/llvm/lib/Target/PowerPC/PPCFastISel.cpp
+++ b/llvm/lib/Target/PowerPC/PPCFastISel.cpp
@@ -2354,7 +2354,8 @@
         PPCSubTarget->hasSPE() ? PPC::EVLDD : PPC::LFD))
     return false;
 
-  MI->eraseFromParent();
+  MachineBasicBlock::iterator I(MI);
+  removeDeadCode(I, std::next(I));
   return true;
 }
 

llvm/lib/Target/X86/X86FastISel.cpp

diff --git a/llvm/lib/Target/X86/X86FastISel.cpp b/llvm/lib/Target/X86/X86FastISel.cpp
index a49ad8b..cbfdc4b 100644
--- a/llvm/lib/Target/X86/X86FastISel.cpp
+++ b/llvm/lib/Target/X86/X86FastISel.cpp
@@ -3998,7 +3998,8 @@
   }
 
   Result->addMemOperand(*FuncInfo.MF, createMachineMemOperandFor(LI));
-  MI->eraseFromParent();
+  MachineBasicBlock::iterator I(MI);
+  removeDeadCode(I, std::next(I));
   return true;
 }