[globalisel][legalizer] G_LOAD/G_STORE NarrowScalar should not emit G_GEP x, 0.
Summary:
When legalizing G_LOAD/G_STORE using NarrowScalar, we should avoid emitting
%0 = G_CONSTANT ty 0
%1 = G_GEP %x, %0
since it's cheaper to not emit the redundant instructions than it is to fold them
away later.
Reviewers: qcolombet, t.p.northover, ab, rovka, aditya_nandakumar, kristof.beyls
Reviewed By: qcolombet
Subscribers: javed.absar, llvm-commits, igorb
Differential Revision: https://reviews.llvm.org/D32746
llvm-svn: 305340
diff --git a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
index 54ef7e5..79d312f 100644
--- a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
@@ -191,6 +191,24 @@
.addUse(Op1);
}
+Optional<MachineInstrBuilder>
+MachineIRBuilder::materializeGEP(unsigned &Res, unsigned Op0,
+ const LLT &ValueTy, uint64_t Value) {
+ assert(Res == 0 && "Res is a result argument");
+ assert(ValueTy.isScalar() && "invalid offset type");
+
+ if (Value == 0) {
+ Res = Op0;
+ return None;
+ }
+
+ Res = MRI->createGenericVirtualRegister(MRI->getType(Op0));
+ unsigned TmpReg = MRI->createGenericVirtualRegister(ValueTy);
+
+ buildConstant(TmpReg, Value);
+ return buildGEP(Res, Op0, TmpReg);
+}
+
MachineInstrBuilder MachineIRBuilder::buildPtrMask(unsigned Res, unsigned Op0,
uint32_t NumBits) {
assert(MRI->getType(Res).isPointer() &&