[SelectionDAG][X86] Add SelectionDAG::getSignedConstant and use it in a few places. (#104555)

PR #80309 proposes to have users of APInt's uint64_t
constructor opt-in to implicit truncation. Currently, that patch
requires SelectionDAG::getConstant to opt-in.

This patch adds getSignedConstant so we can start fixing some of the
cases that require implicit truncation.

4 files changed, 13 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index e7f7653..debecc4 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -2601,7 +2601,7 @@ SDValue SelectionDAGLegalize::expandFrexp(SDNode *Node) const {
   SDValue IsDenormal =
       DAG.getSetCC(dl, SetCCVT, Abs, SmallestNormalizedInt, ISD::SETULT);
 
-  SDValue MinExp = DAG.getConstant(MinExpVal, dl, ExpVT);
+  SDValue MinExp = DAG.getSignedConstant(MinExpVal, dl, ExpVT);
   SDValue Zero = DAG.getConstant(0, dl, ExpVT);
 
   SDValue ScaledAsInt = DAG.getNode(ISD::BITCAST, dl, AsIntVT, ScaleUp);
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 7bf90ce..2401bb5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1747,6 +1747,15 @@ SDValue SelectionDAG::getConstant(const ConstantInt &Val, const SDLoc &DL,
   return Result;
 }
 
+SDValue SelectionDAG::getSignedConstant(int64_t Val, const SDLoc &DL, EVT VT,
+                                        bool isT, bool isO) {
+  unsigned Size = VT.getScalarSizeInBits();
+  assert(
+      isIntN(Size, Val) &&
+      "getSignedConstant with a int64_t value that doesn't fit in the type!");
+  return getConstant(APInt(Size, Val, true), DL, VT, isT, isO);
+}
+
 SDValue SelectionDAG::getAllOnesConstant(const SDLoc &DL, EVT VT, bool IsTarget,
                                          bool IsOpaque) {
   return getConstant(APInt::getAllOnes(VT.getScalarSizeInBits()), DL, VT,
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 7cdd3d4..8e24f5bd 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4474,7 +4474,7 @@ void SelectionDAGBuilder::visitAlloca(const AllocaInst &I) {
 
   // Mask out the low bits for alignment purposes.
   AllocSize = DAG.getNode(ISD::AND, dl, AllocSize.getValueType(), AllocSize,
-                          DAG.getConstant(~StackAlignMask, dl, IntPtr));
+                          DAG.getSignedConstant(~StackAlignMask, dl, IntPtr));
 
   SDValue Ops[] = {
       getRoot(), AllocSize,
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index c1a87de..3c499ca 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -6349,9 +6349,9 @@ SDValue TargetLowering::BuildSDIV(SDNode *N, SelectionDAG &DAG,
     }
 
     MagicFactors.push_back(DAG.getConstant(magics.Magic, dl, SVT));
-    Factors.push_back(DAG.getConstant(NumeratorFactor, dl, SVT));
+    Factors.push_back(DAG.getSignedConstant(NumeratorFactor, dl, SVT));
     Shifts.push_back(DAG.getConstant(magics.ShiftAmount, dl, ShSVT));
-    ShiftMasks.push_back(DAG.getConstant(ShiftMask, dl, SVT));
+    ShiftMasks.push_back(DAG.getSignedConstant(ShiftMask, dl, SVT));
     return true;
   };