GlobalISel: add generic casts to IRTranslator

This adds LLVM's 3 main cast instructions (inttoptr, ptrtoint, bitcast) to the
IRTranslator. The first two are direct translations (with 2 MachineInstr types
each). Since LLT discards information, a bitcast might become trivial and we
emit a COPY in those cases instead.

llvm-svn: 276690

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 82cec258fa6..f7db60f59b5 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -100,6 +100,23 @@ bool IRTranslator::translateBr(const Instruction &Inst) {
   return true;
 }
 
+bool IRTranslator::translateBitCast(const CastInst &CI) {
+  if (LLT{*CI.getDestTy()} == LLT{*CI.getSrcTy()}) {
+    MIRBuilder.buildInstr(TargetOpcode::COPY, getOrCreateVReg(CI),
+                          getOrCreateVReg(*CI.getOperand(0)));
+    return true;
+  }
+  return translateCast(TargetOpcode::G_BITCAST, CI);
+}
+
+bool IRTranslator::translateCast(unsigned Opcode, const CastInst &CI) {
+  unsigned Op = getOrCreateVReg(*CI.getOperand(0));
+  unsigned Res = getOrCreateVReg(CI);
+  MIRBuilder.buildInstr(Opcode, {LLT{*CI.getDestTy()}, LLT{*CI.getSrcTy()}},
+                        Res, Op);
+  return true;
+}
+
 bool IRTranslator::translateStaticAlloca(const AllocaInst &AI) {
   assert(AI.isStaticAlloca() && "only handle static allocas now");
   MachineFunction &MF = MIRBuilder.getMF();
@@ -138,6 +155,14 @@ bool IRTranslator::translate(const Instruction &Inst) {
   case Instruction::Ret:
     return translateReturn(Inst);
 
+  // Casts
+  case Instruction::BitCast:
+    return translateBitCast(cast<CastInst>(Inst));
+  case Instruction::IntToPtr:
+    return translateCast(TargetOpcode::G_INTTOPTR, cast<CastInst>(Inst));
+  case Instruction::PtrToInt:
+    return translateCast(TargetOpcode::G_PTRTOINT, cast<CastInst>(Inst));
+
   case Instruction::Alloca:
     return translateStaticAlloca(cast<AllocaInst>(Inst));