Enable support for vector sext and trunc:
Limit the folding of any_ext and sext into the load operation to scalars.
Limit the active-bits trunc optimization to scalars.
Document vector trunc and vector sext in LangRef.
Similar to commit 126080 (for enabling zext).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126424 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index c5f0324..911dbfd 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3685,7 +3685,9 @@
}
// fold (sext (load x)) -> (sext (truncate (sextload x)))
- if (ISD::isNON_EXTLoad(N0.getNode()) &&
+ // None of the supported targets knows how to perform load and sign extend
+ // in one instruction. We only perform this transformation on scalars.
+ if (ISD::isNON_EXTLoad(N0.getNode()) && !VT.isVector() &&
((!LegalOperations && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadExtLegal(ISD::SEXTLOAD, N0.getValueType()))) {
bool DoXform = true;
@@ -4096,7 +4098,9 @@
}
// fold (aext (load x)) -> (aext (truncate (extload x)))
- if (ISD::isNON_EXTLoad(N0.getNode()) &&
+ // None of the supported targets knows how to perform load and any_ext
+ // in one instruction. We only perform this transformation on scalars.
+ if (ISD::isNON_EXTLoad(N0.getNode()) && !VT.isVector() &&
((!LegalOperations && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadExtLegal(ISD::EXTLOAD, N0.getValueType()))) {
bool DoXform = true;
@@ -4506,14 +4510,17 @@
}
// See if we can simplify the input to this truncate through knowledge that
- // only the low bits are being used. For example "trunc (or (shl x, 8), y)"
- // -> trunc y
- SDValue Shorter =
- GetDemandedBits(N0, APInt::getLowBitsSet(N0.getValueSizeInBits(),
- VT.getSizeInBits()));
- if (Shorter.getNode())
- return DAG.getNode(ISD::TRUNCATE, N->getDebugLoc(), VT, Shorter);
-
+ // only the low bits are being used.
+ // For example "trunc (or (shl x, 8), y)" // -> trunc y
+ // Currenly we only perform this optimization on scalars because vectors
+ // may have different active low bits.
+ if (!VT.isVector()) {
+ SDValue Shorter =
+ GetDemandedBits(N0, APInt::getLowBitsSet(N0.getValueSizeInBits(),
+ VT.getSizeInBits()));
+ if (Shorter.getNode())
+ return DAG.getNode(ISD::TRUNCATE, N->getDebugLoc(), VT, Shorter);
+ }
// fold (truncate (load x)) -> (smaller load x)
// fold (truncate (srl (load x), c)) -> (smaller load (x+c/evtbits))
if (!LegalTypes || TLI.isTypeDesirableForOp(N0.getOpcode(), VT)) {