[PATCH] D140237: [IR][NFC] Add BasicBlock::erase(Instruction *I) for erasing a single Instruction.

[Vasileios Porpodas via Phabricator via llvm-commits]

vporpo updated this revision to Diff 483637.
vporpo added a comment.
Herald added a subscriber: hiraditya.

I->eraseFromParent() now calls BasicBlock::erase(BB). Also BasicBlock::erase(BB) now calls InstList.erase() directly instead of calling BasicBlock::erase(FromIt, ToIt).


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D140237/new/

https://reviews.llvm.org/D140237

Files:
  llvm/include/llvm/IR/BasicBlock.h
  llvm/lib/IR/Instruction.cpp
  llvm/unittests/IR/BasicBlockTest.cpp


Index: llvm/unittests/IR/BasicBlockTest.cpp
===================================================================
--- llvm/unittests/IR/BasicBlockTest.cpp
+++ llvm/unittests/IR/BasicBlockTest.cpp
@@ -541,5 +541,43 @@
   BB0->erase(BB0->begin(), BB0->end());
   EXPECT_TRUE(BB0->empty());
 }
+
+TEST(BasicBlockTest, EraseSingleInstr) {
+  LLVMContext Ctx;
+  std::unique_ptr<Module> M = parseIR(Ctx, R"(
+    define void @f(i32 %a) {
+     bb0:
+       %instr1 = add i32 %a, %a
+       %instr2 = sub i32 %a, %a
+       ret void
+    }
+)");
+  Function *F = &*M->begin();
+
+  auto BB0It = F->begin();
+  BasicBlock *BB0 = &*BB0It;
+
+  auto It = BB0->begin();
+  Instruction *Instr1 = &*It++;
+  Instruction *Instr2 = &*It++;
+  Instruction *Ret = &*It++;
+
+  EXPECT_EQ(BB0->size(), 3u);
+
+  // Erase %instr1
+  BB0->erase(Instr1);
+  EXPECT_EQ(BB0->size(), 2u);
+  EXPECT_EQ(&*BB0->begin(), Instr2);
+
+  // Erase ret
+  BB0->erase(Ret);
+  EXPECT_EQ(BB0->size(), 1u);
+  EXPECT_EQ(&*BB0->begin(), Instr2);
+
+  // Erase %instr2
+  BB0->erase(Instr2);
+  EXPECT_TRUE(BB0->empty());
+}
+
 } // End anonymous namespace.
 } // End llvm namespace.
Index: llvm/lib/IR/Instruction.cpp
===================================================================
--- llvm/lib/IR/Instruction.cpp
+++ llvm/lib/IR/Instruction.cpp
@@ -79,7 +79,7 @@
 }
 
 iplist<Instruction>::iterator Instruction::eraseFromParent() {
-  return getParent()->getInstList().erase(getIterator());
+  return getParent()->erase(this);
 }
 
 /// Insert an unlinked instruction into a basic block immediately before the
Index: llvm/include/llvm/IR/BasicBlock.h
===================================================================
--- llvm/include/llvm/IR/BasicBlock.h
+++ llvm/include/llvm/IR/BasicBlock.h
@@ -490,6 +490,12 @@
   /// \Returns \p ToIt.
   BasicBlock::iterator erase(BasicBlock::iterator FromIt, BasicBlock::iterator ToIt);
 
+  /// Erases \p I from the instruction list. \Returns the iterator of the
+  /// instruction following \p I.
+  BasicBlock::iterator erase(Instruction *I) {
+    return InstList.erase(I->getIterator());
+  }
+
   /// Returns true if there are any uses of this basic block other than
   /// direct branches, switches, etc. to it.
   bool hasAddressTaken() const {


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