[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
Chris Lattner
sabre at nondot.org
Wed Sep 20 23:00:35 PDT 2006
Changes in directory llvm/lib/CodeGen/SelectionDAG:
DAGCombiner.cpp updated: 1.190 -> 1.191
---
Log message:
Generalize (zext (truncate x)) and (sext (truncate x)) folding to work when
the src/dst are not the same size. This catches things like "truncate
32-bit X to 8 bits, then zext to 16", which happens a bit on X86.
---
Diffs of the changes: (+24 -9)
DAGCombiner.cpp | 33 ++++++++++++++++++++++++---------
1 files changed, 24 insertions(+), 9 deletions(-)
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.190 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.191
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.190 Wed Sep 20 01:41:35 2006
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Thu Sep 21 01:00:20 2006
@@ -1766,12 +1766,18 @@
if (N0.getOpcode() == ISD::SIGN_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND)
return DAG.getNode(ISD::SIGN_EXTEND, VT, N0.getOperand(0));
- // fold (sext (truncate x)) -> (sextinreg x) iff x size == sext size.
- if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT&&
- (!AfterLegalize ||
- TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, N0.getValueType())))
- return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0.getOperand(0),
+ // fold (sext (truncate x)) -> (sextinreg x).
+ if (N0.getOpcode() == ISD::TRUNCATE &&
+ (!AfterLegalize || TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, VT))) {
+ SDOperand Op = N0.getOperand(0);
+ if (Op.getValueType() < VT) {
+ Op = DAG.getNode(ISD::ANY_EXTEND, VT, Op);
+ } else if (Op.getValueType() > VT) {
+ Op = DAG.getNode(ISD::TRUNCATE, VT, Op);
+ }
+ return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, Op,
DAG.getValueType(N0.getValueType()));
+ }
// fold (sext (load x)) -> (sext (truncate (sextload x)))
if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse() &&
@@ -1812,10 +1818,19 @@
// fold (zext (aext x)) -> (zext x)
if (N0.getOpcode() == ISD::ZERO_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND)
return DAG.getNode(ISD::ZERO_EXTEND, VT, N0.getOperand(0));
- // fold (zext (truncate x)) -> (zextinreg x) iff x size == zext size.
- if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT&&
- (!AfterLegalize || TLI.isOperationLegal(ISD::AND, N0.getValueType())))
- return DAG.getZeroExtendInReg(N0.getOperand(0), N0.getValueType());
+
+ // fold (zext (truncate x)) -> (and x, mask)
+ if (N0.getOpcode() == ISD::TRUNCATE &&
+ (!AfterLegalize || TLI.isOperationLegal(ISD::AND, VT))) {
+ SDOperand Op = N0.getOperand(0);
+ if (Op.getValueType() < VT) {
+ Op = DAG.getNode(ISD::ANY_EXTEND, VT, Op);
+ } else if (Op.getValueType() > VT) {
+ Op = DAG.getNode(ISD::TRUNCATE, VT, Op);
+ }
+ return DAG.getZeroExtendInReg(Op, N0.getValueType());
+ }
+
// fold (zext (load x)) -> (zext (truncate (zextload x)))
if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse() &&
(!AfterLegalize||TLI.isOperationLegal(ISD::ZEXTLOAD, N0.getValueType()))){
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