GlobalISel: add G_IMPLICIT_DEF instruction.
It looks like there are two target-independent but not GISel instructions that
need legalization, IMPLICIT_DEF and PHI. These are already anomalies since
their operands have important LLTs attached, so to make things more uniform it
seems like a good idea to add generic variants. Starting with G_IMPLICIT_DEF.
llvm-svn: 306875
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 1218232..84b0a0a 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -166,6 +166,20 @@
switch (MI.getOpcode()) {
default:
return UnableToLegalize;
+ case TargetOpcode::G_IMPLICIT_DEF: {
+ int NumParts = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits() /
+ NarrowTy.getSizeInBits();
+
+ SmallVector<unsigned, 2> DstRegs;
+ for (int i = 0; i < NumParts; ++i) {
+ unsigned Dst = MRI.createGenericVirtualRegister(NarrowTy);
+ MIRBuilder.buildUndef(Dst);
+ DstRegs.push_back(Dst);
+ }
+ MIRBuilder.buildMerge(MI.getOperand(0).getReg(), DstRegs);
+ MI.eraseFromParent();
+ return Legalized;
+ }
case TargetOpcode::G_ADD: {
// Expand in terms of carry-setting/consuming G_ADDE instructions.
int NumParts = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits() /
