[TI removal] Update the C API for the move away from `TerminatorInst`.

[chandlerc]

Summary

This updates the C API for the removal of TerminatorInst. It converts
the type query to a predicate query and moves the generic methods to
work on Instruction instances that satisfy this predicate rather than
requiring a specific type. It also clarifies that the C API wrapping
BasicBlock::getTerminator just returns an Instruction. Because this
was always wrapped opaquely as a value and the functions consuming these
values will work on Instruction objects, this shouldn't break any
clients.

This is a completely compatible change to the C API.

[chandlerc]

Sending this for pre-commit review as I want to be sure I'm doing the right thing w/ the C-API here.

[chandlerc]

Ping? Would be really nice to get a review here.

[chandlerc]

Ping again! Also rebase...

[chandlerc]

Ping, rebase, and update to remove all but the type system bits to match the
progress outside of the C API.

[jyknight]

llvm/include/llvm-c/Core.h

2958

I would actually make this function "LLVMIsATerminatorInst", *replacing* the LLVMIsATermiantorInst function defined using "macro" at the top. (A similar thing was done with e.g. LLVMIsAMDNode). With that, I think this change will be 100% compatible in the C API.

3102–3103

(LLVMIsATerminator)

[chandlerc]

Update based on Jame's suggestion.

[chandlerc]

Fix one more place.

[chandlerc]

Done.

[jyknight]

LGTM.

llvm/include/llvm-c/Core.h

3103

Typo: "eturns"

llvm/include/llvm-c/Core.h

macro(Instruction)                      \
       macro(GetElementPtrInst)              \
       macro(InsertElementInst)              \
       macro(InsertValueInst)                \
       macro(LandingPadInst)                 \
       macro(PHINode)                        \
       macro(SelectInst)                     \
       macro(ShuffleVectorInst)              \
       macro(StoreInst)                      \
-      macro(TerminatorInst)                 \
-        macro(BranchInst)                   \
-        macro(IndirectBrInst)               \
-        macro(InvokeInst)                   \
-        macro(ReturnInst)                   \
-        macro(SwitchInst)                   \
-        macro(UnreachableInst)              \
-        macro(ResumeInst)                   \
-        macro(CleanupReturnInst)            \
-        macro(CatchReturnInst)              \
+      macro(BranchInst)                     \
+      macro(IndirectBrInst)                 \
+      macro(InvokeInst)                     \
+      macro(ReturnInst)                     \
+      macro(SwitchInst)                     \
+      macro(UnreachableInst)                \
+      macro(ResumeInst)                     \
+      macro(CleanupReturnInst)              \
+      macro(CatchReturnInst)                \
       macro(FuncletPadInst)                 \
         macro(CatchPadInst)                 \
         macro(CleanupPadInst)               \
       macro(UnaryInstruction)               \
         macro(AllocaInst)                   \
         macro(CastInst)                     \
           macro(AddrSpaceCastInst)          \
           macro(BitCastInst)                \

 LLVMValueRef LLVMGetBasicBlockParent(LLVMBasicBlockRef BB);
 
 /**
  * Obtain the terminator instruction for a basic block.
  *
  * If the basic block does not have a terminator (it is not well-formed
  * if it doesn't), then NULL is returned.
  *
- * The returned LLVMValueRef corresponds to a llvm::TerminatorInst.
+ * The returned LLVMValueRef corresponds to an llvm::Instruction.
  *
  * @see llvm::BasicBlock::getTerminator()
  */
 LLVMValueRef LLVMGetBasicBlockTerminator(LLVMBasicBlockRef BB);
 
 /**
  * Obtain the number of basic blocks in a function.
  *

  *   * The instruction has no parent
  *   * The instruction has no name
  *
  * @see llvm::Instruction::clone()
  */
 LLVMValueRef LLVMInstructionClone(LLVMValueRef Inst);
 
 /**
+ * Determine whether an instruction is a terminator. This routine is named to
+ * be compatible with historical functions that did this by querying the
+ * underlying C++ type.
+ *
+ * @see llvm::Instruction::isTerminator()
+ */
+LLVMValueRef LLVMIsATerminatorInst(LLVMValueRef Inst);
+
+/**
  * @defgroup LLVMCCoreValueInstructionCall Call Sites and Invocations
  *
  * Functions in this group apply to instructions that refer to call
  * sites and invocations. These correspond to C++ types in the
  * llvm::CallInst class tree.
  *
  * @{
  */

 
 /**
  * @}
  */
 
 /**
  * @defgroup LLVMCCoreValueInstructionTerminator Terminators
  *
- * Functions in this group only apply to instructions that map to
- * llvm::TerminatorInst instances.
+ * Functions in this group only apply to instructions for which
+ * LLVMIsATerminatorInst eturns true.
  *
  * @{
  */
 
 /**
  * Return the number of successors that this terminator has.
  *
- * @see llvm::TerminatorInst::getNumSuccessors
+ * @see llvm::Instruction::getNumSuccessors
  */
 unsigned LLVMGetNumSuccessors(LLVMValueRef Term);
 
 /**
  * Return the specified successor.
  *
- * @see llvm::TerminatorInst::getSuccessor
+ * @see llvm::Instruction::getSuccessor
  */
 LLVMBasicBlockRef LLVMGetSuccessor(LLVMValueRef Term, unsigned i);
 
 /**
  * Update the specified successor to point at the provided block.
  *
- * @see llvm::TerminatorInst::setSuccessor
+ * @see llvm::Instruction::setSuccessor
  */
 void LLVMSetSuccessor(LLVMValueRef Term, unsigned i, LLVMBasicBlockRef block);
 
 /**
  * Return if a branch is conditional.
  *
  * This only works on llvm::BranchInst instructions.
  *

llvm/lib/IR/Core.cpp

 }
 
 LLVMValueRef LLVMInstructionClone(LLVMValueRef Inst) {
   if (Instruction *C = dyn_cast<Instruction>(unwrap(Inst)))
     return wrap(C->clone());
   return nullptr;
 }
 
+LLVMValueRef LLVMIsATerminatorInst(LLVMValueRef Inst) {
+  Instruction *I = dyn_cast<Instruction>(unwrap(Inst));
+  return (I && I->isTerminator()) ? wrap(I) : nullptr;
+}
+
 unsigned LLVMGetNumArgOperands(LLVMValueRef Instr) {
   if (FuncletPadInst *FPI = dyn_cast<FuncletPadInst>(unwrap(Instr))) {
     return FPI->getNumArgOperands();
   }
   return CallSite(unwrap<Instruction>(Instr)).getNumArgOperands();
 }
 
 /*--.. Call and invoke instructions ........................................--*/
if (CleanupReturnInst *CRI = dyn_cast<CleanupReturnInst>(unwrap(Invoke))) {
     return CSI->setUnwindDest(unwrap(B));
   }
   unwrap<InvokeInst>(Invoke)->setUnwindDest(unwrap(B));
 }
 
 /*--.. Operations on terminators ...........................................--*/
 
 unsigned LLVMGetNumSuccessors(LLVMValueRef Term) {
-  return unwrap<TerminatorInst>(Term)->getNumSuccessors();
+  return unwrap<Instruction>(Term)->getNumSuccessors();
 }
 
 LLVMBasicBlockRef LLVMGetSuccessor(LLVMValueRef Term, unsigned i) {
-  return wrap(unwrap<TerminatorInst>(Term)->getSuccessor(i));
+  return wrap(unwrap<Instruction>(Term)->getSuccessor(i));
 }
 
 void LLVMSetSuccessor(LLVMValueRef Term, unsigned i, LLVMBasicBlockRef block) {
-  return unwrap<TerminatorInst>(Term)->setSuccessor(i,unwrap(block));
+  return unwrap<Instruction>(Term)->setSuccessor(i, unwrap(block));
 }
 
 /*--.. Operations on branch instructions (only) ............................--*/
 
 LLVMBool LLVMIsConditional(LLVMValueRef Branch) {
   return unwrap<BranchInst>(Branch)->isConditional();
 }