[llvm-commits] CVS: llvm/lib/Transforms/Scalar/SCCP.cpp
Chris Lattner
lattner at cs.uiuc.edu
Tue Feb 7 18:38:22 PST 2006
Changes in directory llvm/lib/Transforms/Scalar:
SCCP.cpp updated: 1.128 -> 1.129
---
Log message:
Implement some more interesting select sccp cases. This implements:
test/Regression/Transforms/SCCP/select.ll
---
Diffs of the changes: (+35 -15)
SCCP.cpp | 50 +++++++++++++++++++++++++++++++++++---------------
1 files changed, 35 insertions(+), 15 deletions(-)
Index: llvm/lib/Transforms/Scalar/SCCP.cpp
diff -u llvm/lib/Transforms/Scalar/SCCP.cpp:1.128 llvm/lib/Transforms/Scalar/SCCP.cpp:1.129
--- llvm/lib/Transforms/Scalar/SCCP.cpp:1.128 Sun Jan 22 17:32:06 2006
+++ llvm/lib/Transforms/Scalar/SCCP.cpp Tue Feb 7 20:38:11 2006
@@ -241,6 +241,11 @@
else if (IV.getConstant() != MergeWithV.getConstant())
markOverdefined(IV, V);
}
+
+ inline void mergeInValue(Value *V, LatticeVal &MergeWithV) {
+ return mergeInValue(ValueState[V], V, MergeWithV);
+ }
+
// getValueState - Return the LatticeVal object that corresponds to the value.
// This function is necessary because not all values should start out in the
@@ -589,23 +594,38 @@
void SCCPSolver::visitSelectInst(SelectInst &I) {
LatticeVal &CondValue = getValueState(I.getCondition());
- if (CondValue.isOverdefined())
- markOverdefined(&I);
- else if (CondValue.isConstant()) {
+ if (CondValue.isUndefined())
+ return;
+ if (CondValue.isConstant()) {
+ Value *InVal = 0;
if (CondValue.getConstant() == ConstantBool::True) {
- LatticeVal &Val = getValueState(I.getTrueValue());
- if (Val.isOverdefined())
- markOverdefined(&I);
- else if (Val.isConstant())
- markConstant(&I, Val.getConstant());
+ mergeInValue(&I, getValueState(I.getTrueValue()));
+ return;
} else if (CondValue.getConstant() == ConstantBool::False) {
- LatticeVal &Val = getValueState(I.getFalseValue());
- if (Val.isOverdefined())
- markOverdefined(&I);
- else if (Val.isConstant())
- markConstant(&I, Val.getConstant());
- } else
- markOverdefined(&I);
+ mergeInValue(&I, getValueState(I.getFalseValue()));
+ return;
+ }
+ }
+
+ // Otherwise, the condition is overdefined or a constant we can't evaluate.
+ // See if we can produce something better than overdefined based on the T/F
+ // value.
+ LatticeVal &TVal = getValueState(I.getTrueValue());
+ LatticeVal &FVal = getValueState(I.getFalseValue());
+
+ // select ?, C, C -> C.
+ if (TVal.isConstant() && FVal.isConstant() &&
+ TVal.getConstant() == FVal.getConstant()) {
+ markConstant(&I, FVal.getConstant());
+ return;
+ }
+
+ if (TVal.isUndefined()) { // select ?, undef, X -> X.
+ mergeInValue(&I, FVal);
+ } else if (FVal.isUndefined()) { // select ?, X, undef -> X.
+ mergeInValue(&I, TVal);
+ } else {
+ markOverdefined(&I);
}
}
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