[DAG] Move integer setcc %x, %x folding into FoldSetCC

First step towards PR40800 - I intend to move the float case in a separate future patch.

I had to tweak the (overly reduced) thumb2 test and the x86 widening test change is annoying (no longer rematerializable) but we should address this separately.

Differential Revision: https://reviews.llvm.org/D59244

llvm-svn: 356040

2 files changed, 6 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index a87883bbe40..fe3f2b99ba7 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1974,6 +1974,10 @@ SDValue SelectionDAG::FoldSetCC(EVT VT, SDValue N1, SDValue N2,
     break;
   }
 
+  // We can always fold X == X for integer setcc's.
+  if (N1 == N2 && OpVT.isInteger())
+    return getBoolConstant(ISD::isTrueWhenEqual(Cond), dl, VT, OpVT);
+
   if (ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2)) {
     const APInt &C2 = N2C->getAPIntValue();
     if (ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1)) {
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 06596dbaf70..2a1b9745490 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -3004,13 +3004,10 @@ SDValue TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
   if (N0 == N1) {
     // The sext(setcc()) => setcc() optimization relies on the appropriate
     // constant being emitted.
+    assert(!N0.getValueType().isInteger() &&
+           "Integer types should be handled by FoldSetCC");
 
     bool EqTrue = ISD::isTrueWhenEqual(Cond);
-
-    // We can always fold X == X for integer setcc's.
-    if (N0.getValueType().isInteger())
-      return DAG.getBoolConstant(EqTrue, dl, VT, OpVT);
-
     unsigned UOF = ISD::getUnorderedFlavor(Cond);
     if (UOF == 2) // FP operators that are undefined on NaNs.
       return DAG.getBoolConstant(EqTrue, dl, VT, OpVT);