On x86, if the only use of a i64 load is a i64 store, generate a pair of double load and store instead.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66776 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 2de7377..f15acd7 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -8285,14 +8285,21 @@
/// PerformSTORECombine - Do target-specific dag combines on STORE nodes.
static SDValue PerformSTORECombine(SDNode *N, SelectionDAG &DAG,
- const X86Subtarget *Subtarget) {
+ const X86Subtarget *Subtarget) {
// Turn load->store of MMX types into GPR load/stores. This avoids clobbering
// the FP state in cases where an emms may be missing.
// A preferable solution to the general problem is to figure out the right
// places to insert EMMS. This qualifies as a quick hack.
+
+ // Similarly, turn load->store of i64 into double load/stores in 32-bit mode.
StoreSDNode *St = cast<StoreSDNode>(N);
- if (St->getValue().getValueType().isVector() &&
- St->getValue().getValueType().getSizeInBits() == 64 &&
+ MVT VT = St->getValue().getValueType();
+ if (VT.getSizeInBits() != 64)
+ return SDValue();
+
+ bool F64IsLegal = !UseSoftFloat && !NoImplicitFloat && Subtarget->hasSSE2();
+ if ((VT.isVector() ||
+ (VT == MVT::i64 && F64IsLegal && !Subtarget->is64Bit())) &&
isa<LoadSDNode>(St->getValue()) &&
!cast<LoadSDNode>(St->getValue())->isVolatile() &&
St->getChain().hasOneUse() && !St->isVolatile()) {
@@ -8316,60 +8323,72 @@
Ops.push_back(ChainVal->getOperand(i));
}
}
- if (Ld) {
- DebugLoc DL = N->getDebugLoc();
- // If we are a 64-bit capable x86, lower to a single movq load/store pair.
- if (Subtarget->is64Bit()) {
- SDValue NewLd = DAG.getLoad(MVT::i64, DL, Ld->getChain(),
- Ld->getBasePtr(), Ld->getSrcValue(),
- Ld->getSrcValueOffset(), Ld->isVolatile(),
- Ld->getAlignment());
- SDValue NewChain = NewLd.getValue(1);
- if (TokenFactorIndex != -1) {
- Ops.push_back(NewChain);
- NewChain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, &Ops[0],
- Ops.size());
- }
- return DAG.getStore(NewChain, DL, NewLd, St->getBasePtr(),
- St->getSrcValue(), St->getSrcValueOffset(),
- St->isVolatile(), St->getAlignment());
- }
- // Otherwise, lower to two 32-bit copies.
- SDValue LoAddr = Ld->getBasePtr();
- SDValue HiAddr = DAG.getNode(ISD::ADD, DL, MVT::i32, LoAddr,
- DAG.getConstant(4, MVT::i32));
+ if (!Ld || !ISD::isNormalLoad(Ld))
+ return SDValue();
- SDValue LoLd = DAG.getLoad(MVT::i32, DL, Ld->getChain(), LoAddr,
- Ld->getSrcValue(), Ld->getSrcValueOffset(),
- Ld->isVolatile(), Ld->getAlignment());
- SDValue HiLd = DAG.getLoad(MVT::i32, DL, Ld->getChain(), HiAddr,
- Ld->getSrcValue(), Ld->getSrcValueOffset()+4,
- Ld->isVolatile(),
- MinAlign(Ld->getAlignment(), 4));
+ // If this is not the MMX case, i.e. we are just turning i64 load/store
+ // into f64 load/store, avoid the transformation if there are multiple
+ // uses of the loaded value.
+ if (!VT.isVector() && !Ld->hasNUsesOfValue(1, 0))
+ return SDValue();
- SDValue NewChain = LoLd.getValue(1);
+ DebugLoc LdDL = Ld->getDebugLoc();
+ DebugLoc StDL = N->getDebugLoc();
+ // If we are a 64-bit capable x86, lower to a single movq load/store pair.
+ // Otherwise, if it's legal to use f64 SSE instructions, use f64 load/store
+ // pair instead.
+ if (Subtarget->is64Bit() || F64IsLegal) {
+ MVT LdVT = Subtarget->is64Bit() ? MVT::i64 : MVT::f64;
+ SDValue NewLd = DAG.getLoad(LdVT, LdDL, Ld->getChain(),
+ Ld->getBasePtr(), Ld->getSrcValue(),
+ Ld->getSrcValueOffset(), Ld->isVolatile(),
+ Ld->getAlignment());
+ SDValue NewChain = NewLd.getValue(1);
if (TokenFactorIndex != -1) {
- Ops.push_back(LoLd);
- Ops.push_back(HiLd);
- NewChain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, &Ops[0],
+ Ops.push_back(NewChain);
+ NewChain = DAG.getNode(ISD::TokenFactor, LdDL, MVT::Other, &Ops[0],
Ops.size());
}
-
- LoAddr = St->getBasePtr();
- HiAddr = DAG.getNode(ISD::ADD, DL, MVT::i32, LoAddr,
- DAG.getConstant(4, MVT::i32));
-
- SDValue LoSt = DAG.getStore(NewChain, DL, LoLd, LoAddr,
+ return DAG.getStore(NewChain, StDL, NewLd, St->getBasePtr(),
St->getSrcValue(), St->getSrcValueOffset(),
St->isVolatile(), St->getAlignment());
- SDValue HiSt = DAG.getStore(NewChain, DL, HiLd, HiAddr,
- St->getSrcValue(),
- St->getSrcValueOffset() + 4,
- St->isVolatile(),
- MinAlign(St->getAlignment(), 4));
- return DAG.getNode(ISD::TokenFactor, DL, MVT::Other, LoSt, HiSt);
}
+
+ // Otherwise, lower to two pairs of 32-bit loads / stores.
+ SDValue LoAddr = Ld->getBasePtr();
+ SDValue HiAddr = DAG.getNode(ISD::ADD, LdDL, MVT::i32, LoAddr,
+ DAG.getConstant(4, MVT::i32));
+
+ SDValue LoLd = DAG.getLoad(MVT::i32, LdDL, Ld->getChain(), LoAddr,
+ Ld->getSrcValue(), Ld->getSrcValueOffset(),
+ Ld->isVolatile(), Ld->getAlignment());
+ SDValue HiLd = DAG.getLoad(MVT::i32, LdDL, Ld->getChain(), HiAddr,
+ Ld->getSrcValue(), Ld->getSrcValueOffset()+4,
+ Ld->isVolatile(),
+ MinAlign(Ld->getAlignment(), 4));
+
+ SDValue NewChain = LoLd.getValue(1);
+ if (TokenFactorIndex != -1) {
+ Ops.push_back(LoLd);
+ Ops.push_back(HiLd);
+ NewChain = DAG.getNode(ISD::TokenFactor, LdDL, MVT::Other, &Ops[0],
+ Ops.size());
+ }
+
+ LoAddr = St->getBasePtr();
+ HiAddr = DAG.getNode(ISD::ADD, StDL, MVT::i32, LoAddr,
+ DAG.getConstant(4, MVT::i32));
+
+ SDValue LoSt = DAG.getStore(NewChain, StDL, LoLd, LoAddr,
+ St->getSrcValue(), St->getSrcValueOffset(),
+ St->isVolatile(), St->getAlignment());
+ SDValue HiSt = DAG.getStore(NewChain, StDL, HiLd, HiAddr,
+ St->getSrcValue(),
+ St->getSrcValueOffset() + 4,
+ St->isVolatile(),
+ MinAlign(St->getAlignment(), 4));
+ return DAG.getNode(ISD::TokenFactor, StDL, MVT::Other, LoSt, HiSt);
}
return SDValue();
}