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

4 files changed, 13 insertions, 7 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64FastISel.cpp b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
index dfc08a12f51..7a7b0dd20a4 100644
--- a/llvm/lib/Target/AArch64/AArch64FastISel.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
@@ -2016,8 +2016,9 @@ bool AArch64FastISel::selectLoad(const Instruction *I) {
       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 @@ bool AArch64FastISel::selectLoad(const Instruction *I) {
           break;
         }
       }
-      MI->eraseFromParent();
+      MachineBasicBlock::iterator I(MI);
+      removeDeadCode(I, std::next(I));
       MI = nullptr;
       if (Reg)
         MI = MRI.getUniqueVRegDef(Reg);
@@ -4508,7 +4510,8 @@ bool AArch64FastISel::optimizeIntExtLoad(const Instruction *I, MVT RetVT,
             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;
diff --git a/llvm/lib/Target/ARM/ARMFastISel.cpp b/llvm/lib/Target/ARM/ARMFastISel.cpp
index fd3d10aa10c..a50abfdbee4 100644
--- a/llvm/lib/Target/ARM/ARMFastISel.cpp
+++ b/llvm/lib/Target/ARM/ARMFastISel.cpp
@@ -2951,7 +2951,8 @@ bool ARMFastISel::tryToFoldLoadIntoMI(MachineInstr *MI, unsigned OpNo,
   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;
 }
 
diff --git a/llvm/lib/Target/PowerPC/PPCFastISel.cpp b/llvm/lib/Target/PowerPC/PPCFastISel.cpp
index 668169839e7..aa55ac1f7ac 100644
--- a/llvm/lib/Target/PowerPC/PPCFastISel.cpp
+++ b/llvm/lib/Target/PowerPC/PPCFastISel.cpp
@@ -2354,7 +2354,8 @@ bool PPCFastISel::tryToFoldLoadIntoMI(MachineInstr *MI, unsigned OpNo,
         PPCSubTarget->hasSPE() ? PPC::EVLDD : PPC::LFD))
     return false;
 
-  MI->eraseFromParent();
+  MachineBasicBlock::iterator I(MI);
+  removeDeadCode(I, std::next(I));
   return true;
 }
 
diff --git a/llvm/lib/Target/X86/X86FastISel.cpp b/llvm/lib/Target/X86/X86FastISel.cpp
index a49ad8bd59d..cbfdc4b3b93 100644
--- a/llvm/lib/Target/X86/X86FastISel.cpp
+++ b/llvm/lib/Target/X86/X86FastISel.cpp
@@ -3998,7 +3998,8 @@ bool X86FastISel::tryToFoldLoadIntoMI(MachineInstr *MI, unsigned OpNo,
   }
 
   Result->addMemOperand(*FuncInfo.MF, createMachineMemOperandFor(LI));
-  MI->eraseFromParent();
+  MachineBasicBlock::iterator I(MI);
+  removeDeadCode(I, std::next(I));
   return true;
 }