SelectionDAG: create correct BooleanContent constants
Occasionally DAGCombiner can spot that a SETCC operation is completely
redundant and reduce it to "all true" or "all false". If this happens to a
vector, the value produced has to take account of what a normal comparison
would have produced, which may be an all-1s bitmask.
The fix in SelectionDAG.cpp is tested, however, as far as I can see the code in
TargetLowering.cpp is possibly unreachable and almost certainly irrelevant when
triggered so there are no tests. However, I believe it's still clearly the
right change and may save someone else some hassle if it suddenly becomes
reachable. So I'm doing it anyway.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190147 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 95dc5ab..1472490 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1554,7 +1554,12 @@
case ISD::SETFALSE:
case ISD::SETFALSE2: return getConstant(0, VT);
case ISD::SETTRUE:
- case ISD::SETTRUE2: return getConstant(1, VT);
+ case ISD::SETTRUE2: {
+ const TargetLowering *TLI = TM.getTargetLowering();
+ TargetLowering::BooleanContent Cnt = TLI->getBooleanContents(VT.isVector());
+ return getConstant(
+ Cnt == TargetLowering::ZeroOrNegativeOneBooleanContent ? -1ULL : 1, VT);
+ }
case ISD::SETOEQ:
case ISD::SETOGT:
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index df67221..f2199d7 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1080,7 +1080,11 @@
case ISD::SETFALSE:
case ISD::SETFALSE2: return DAG.getConstant(0, VT);
case ISD::SETTRUE:
- case ISD::SETTRUE2: return DAG.getConstant(1, VT);
+ case ISD::SETTRUE2: {
+ TargetLowering::BooleanContent Cnt = getBooleanContents(VT.isVector());
+ return DAG.getConstant(
+ Cnt == TargetLowering::ZeroOrNegativeOneBooleanContent ? -1ULL : 1, VT);
+ }
}
// Ensure that the constant occurs on the RHS, and fold constant