[GISel]: Don't create G_MUL with 1 during translation of GEP
When element size is 1, it's just wasteful to create MUL with 1.
https://reviews.llvm.org/D41738
llvm-svn: 321857
diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 705d4de..7f1e182 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -516,10 +516,6 @@
Offset = 0;
}
- // N = N + Idx * ElementSize;
- unsigned ElementSizeReg =
- getOrCreateVReg(*ConstantInt::get(OffsetIRTy, ElementSize));
-
unsigned IdxReg = getOrCreateVReg(*Idx);
if (MRI->getType(IdxReg) != OffsetTy) {
unsigned NewIdxReg = MRI->createGenericVirtualRegister(OffsetTy);
@@ -527,11 +523,20 @@
IdxReg = NewIdxReg;
}
- unsigned OffsetReg = MRI->createGenericVirtualRegister(OffsetTy);
- MIRBuilder.buildMul(OffsetReg, ElementSizeReg, IdxReg);
+ // N = N + Idx * ElementSize;
+ // Avoid doing it for ElementSize of 1.
+ unsigned GepOffsetReg;
+ if (ElementSize != 1) {
+ unsigned ElementSizeReg =
+ getOrCreateVReg(*ConstantInt::get(OffsetIRTy, ElementSize));
+
+ GepOffsetReg = MRI->createGenericVirtualRegister(OffsetTy);
+ MIRBuilder.buildMul(GepOffsetReg, ElementSizeReg, IdxReg);
+ } else
+ GepOffsetReg = IdxReg;
unsigned NewBaseReg = MRI->createGenericVirtualRegister(PtrTy);
- MIRBuilder.buildGEP(NewBaseReg, BaseReg, OffsetReg);
+ MIRBuilder.buildGEP(NewBaseReg, BaseReg, GepOffsetReg);
BaseReg = NewBaseReg;
}
}