[DAG] select (sext m), (add X, C), X --> (add X, (and C, (sext m)))) (#83640)

- [DAG][X86] Add tests for Folding select m, add(X, C), X --> add (X, and(C, m))(NFC)
- [DAG][X86] Fold select (sext m), (add X, C), X --> (add X, (and C, (sext m))))
- Fixes: #66101

Author: elhewaty

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -12074,6 +12074,17 @@ SDValue DAGCombiner::visitVSELECT(SDNode *N) {
   if (SDValue F = extractBooleanFlip(N0, DAG, TLI, false))
     return DAG.getSelect(DL, VT, F, N2, N1);
 
+  // select (sext m), (add X, C), X --> (add X, (and C, (sext m))))
+  if (N1.getOpcode() == ISD::ADD && N1.getOperand(0) == N2 && N1->hasOneUse() &&
+      DAG.isConstantIntBuildVectorOrConstantInt(N1.getOperand(1)) &&
+      N0.getScalarValueSizeInBits() == N1.getScalarValueSizeInBits() &&
+      TLI.getBooleanContents(N0.getValueType()) ==
+          TargetLowering::ZeroOrNegativeOneBooleanContent) {
+    return DAG.getNode(
+        ISD::ADD, DL, N1.getValueType(), N2,
+        DAG.getNode(ISD::AND, DL, N0.getValueType(), N1.getOperand(1), N0));
+  }
+
   // Canonicalize integer abs.
   // vselect (setg[te] X,  0),  X, -X ->
   // vselect (setgt    X, -1),  X, -X ->

llvm/test/CodeGen/X86/vselect.ll

@@ -4,6 +4,35 @@
 ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx | FileCheck %s --check-prefixes=AVX,AVX1
 ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx2 | FileCheck %s --check-prefixes=AVX,AVX2
 
+; PR66101 - Fold select (sext m), (add X, C), X --> (add X, (and C, (sext m))))
+define <4 x i32> @masked_select_const(<4 x i32> %a, <4 x i32> %x, <4 x i32> %y) {
+; SSE-LABEL: masked_select_const:
+; SSE:       # %bb.0:
+; SSE-NEXT:    pcmpgtd %xmm2, %xmm1
+; SSE-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1
+; SSE-NEXT:    paddd %xmm1, %xmm0
+; SSE-NEXT:    retq
+;
+; AVX1-LABEL: masked_select_const:
+; AVX1:       # %bb.0:
+; AVX1-NEXT:    vpcmpgtd %xmm2, %xmm1, %xmm1
+; AVX1-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1, %xmm1
+; AVX1-NEXT:    vpaddd %xmm1, %xmm0, %xmm0
+; AVX1-NEXT:    retq
+;
+; AVX2-LABEL: masked_select_const:
+; AVX2:       # %bb.0:
+; AVX2-NEXT:    vpbroadcastd {{.*#+}} xmm3 = [4294967272,4294967272,4294967272,4294967272]
+; AVX2-NEXT:    vpcmpgtd %xmm2, %xmm1, %xmm1
+; AVX2-NEXT:    vpand %xmm3, %xmm1, %xmm1
+; AVX2-NEXT:    vpaddd %xmm1, %xmm0, %xmm0
+; AVX2-NEXT:    retq
+  %sub.i = add <4 x i32> %a, <i32 -24, i32 -24, i32 -24, i32 -24>
+  %cmp.i = icmp sgt <4 x i32> %x, %y
+  %sel = select <4 x i1> %cmp.i, <4 x i32> %sub.i, <4 x i32> %a
+  ret <4 x i32> %sel
+}
+
 ; Verify that we don't emit packed vector shifts instructions if the
 ; condition used by the vector select is a vector of constants.