GlobalISel: translate GEP instructions.
Unlike SDag, we use a separate G_GEP instruction (much simplified, only taking
a single byte offset) to preserve the pointer type information through
selection.
llvm-svn: 281205
diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 6650a1e..c891502 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -20,6 +20,7 @@
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Function.h"
+#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
@@ -287,6 +288,77 @@
return true;
}
+bool IRTranslator::translateGetElementPtr(const User &U) {
+ // FIXME: support vector GEPs.
+ if (U.getType()->isVectorTy())
+ return false;
+
+ Value &Op0 = *U.getOperand(0);
+ unsigned BaseReg = getOrCreateVReg(Op0);
+ LLT PtrTy(*Op0.getType());
+ unsigned PtrSize = DL->getPointerSizeInBits(PtrTy.getAddressSpace());
+ LLT OffsetTy = LLT::scalar(PtrSize);
+
+ int64_t Offset = 0;
+ for (gep_type_iterator GTI = gep_type_begin(&U), E = gep_type_end(&U);
+ GTI != E; ++GTI) {
+ const Value *Idx = GTI.getOperand();
+ if (StructType *StTy = dyn_cast<StructType>(*GTI)) {
+ unsigned Field = cast<Constant>(Idx)->getUniqueInteger().getZExtValue();
+ Offset += DL->getStructLayout(StTy)->getElementOffset(Field);
+ continue;
+ } else {
+ uint64_t ElementSize = DL->getTypeAllocSize(GTI.getIndexedType());
+
+ // If this is a scalar constant or a splat vector of constants,
+ // handle it quickly.
+ if (const auto *CI = dyn_cast<ConstantInt>(Idx)) {
+ Offset += ElementSize * CI->getSExtValue();
+ continue;
+ }
+
+ if (Offset != 0) {
+ unsigned NewBaseReg = MRI->createGenericVirtualRegister(PtrTy);
+ unsigned OffsetReg = MRI->createGenericVirtualRegister(OffsetTy);
+ MIRBuilder.buildConstant(OffsetReg, Offset);
+ MIRBuilder.buildGEP(NewBaseReg, BaseReg, OffsetReg);
+
+ BaseReg = NewBaseReg;
+ Offset = 0;
+ }
+
+ // N = N + Idx * ElementSize;
+ unsigned ElementSizeReg = MRI->createGenericVirtualRegister(OffsetTy);
+ MIRBuilder.buildConstant(ElementSizeReg, ElementSize);
+
+ unsigned IdxReg = getOrCreateVReg(*Idx);
+ if (MRI->getType(IdxReg) != OffsetTy) {
+ unsigned NewIdxReg = MRI->createGenericVirtualRegister(OffsetTy);
+ MIRBuilder.buildSExtOrTrunc(NewIdxReg, IdxReg);
+ IdxReg = NewIdxReg;
+ }
+
+ unsigned OffsetReg = MRI->createGenericVirtualRegister(OffsetTy);
+ MIRBuilder.buildMul(OffsetReg, ElementSizeReg, IdxReg);
+
+ unsigned NewBaseReg = MRI->createGenericVirtualRegister(PtrTy);
+ MIRBuilder.buildGEP(NewBaseReg, BaseReg, OffsetReg);
+ BaseReg = NewBaseReg;
+ }
+ }
+
+ if (Offset != 0) {
+ unsigned OffsetReg = MRI->createGenericVirtualRegister(OffsetTy);
+ MIRBuilder.buildConstant(OffsetReg, Offset);
+ MIRBuilder.buildGEP(getOrCreateVReg(U), BaseReg, OffsetReg);
+ return true;
+ }
+
+ MIRBuilder.buildCopy(getOrCreateVReg(U), BaseReg);
+ return true;
+}
+
+
bool IRTranslator::translateKnownIntrinsic(const CallInst &CI,
Intrinsic::ID ID) {
unsigned Op = 0;