[llvm] 7ec8fc2 - [X86] combineAnd() - per-element simplification - call SimplifyDemandedBits using mask demanded bits if SimplifyDemandedVectorElts fails

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2022-01-31T13:58:00Z
New Revision: 7ec8fc29321c698af665072424bc02a87369c8ad

URL: https://github.com/llvm/llvm-project/commit/7ec8fc29321c698af665072424bc02a87369c8ad
DIFF: https://github.com/llvm/llvm-project/commit/7ec8fc29321c698af665072424bc02a87369c8ad.diff

LOG: [X86] combineAnd() - per-element simplification - call SimplifyDemandedBits using mask demanded bits if SimplifyDemandedVectorElts fails

We already call SimplifyDemandedVectorElts using whether each vector mask element is zero/nonzero, this just extends this to also try SimplifyDemandedBits using the demanded bits mask generated from the nonzero elements.

This also requires an additional TargetLowering::SimplifyDemandedBits DemandedBits/DemandedElts wrapper.

Added: 
    

Modified: 
    llvm/include/llvm/CodeGen/TargetLowering.h
    llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    llvm/lib/Target/X86/X86ISelLowering.cpp
    llvm/test/CodeGen/X86/vector_splat-const-shift-of-constmasked.ll

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/CodeGen/TargetLowering.h b/llvm/include/llvm/CodeGen/TargetLowering.h
index bec1915705947..94d845b39c148 100644
--- a/llvm/include/llvm/CodeGen/TargetLowering.h
+++ b/llvm/include/llvm/CodeGen/TargetLowering.h
@@ -3485,6 +3485,12 @@ class TargetLowering : public TargetLoweringBase {
   bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
                             DAGCombinerInfo &DCI) const;
 
+  /// Helper wrapper around SimplifyDemandedBits.
+  /// Adds Op back to the worklist upon success.
+  bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
+                            const APInt &DemandedElts,
+                            DAGCombinerInfo &DCI) const;
+
   /// More limited version of SimplifyDemandedBits that can be used to "look
   /// through" ops that don't contribute to the DemandedBits/DemandedElts -
   /// bitwise ops etc.

diff  --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index ba6cae00bc50e..ff57725ba846b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -605,6 +605,23 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
   return Simplified;
 }
 
+bool TargetLowering::SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
+                                          const APInt &DemandedElts,
+                                          DAGCombinerInfo &DCI) const {
+  SelectionDAG &DAG = DCI.DAG;
+  TargetLoweringOpt TLO(DAG, !DCI.isBeforeLegalize(),
+                        !DCI.isBeforeLegalizeOps());
+  KnownBits Known;
+
+  bool Simplified =
+      SimplifyDemandedBits(Op, DemandedBits, DemandedElts, Known, TLO);
+  if (Simplified) {
+    DCI.AddToWorklist(Op.getNode());
+    DCI.CommitTargetLoweringOpt(TLO);
+  }
+  return Simplified;
+}
+
 bool TargetLowering::SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
                                           KnownBits &Known,
                                           TargetLoweringOpt &TLO,

diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index d4b0c13c0ffd9..90753b5b4d33c 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -46907,14 +46907,18 @@ static SDValue combineAnd(SDNode *N, SelectionDAG &DAG,
       if (!getTargetConstantBitsFromNode(Op, EltSizeInBits, UndefElts, EltBits))
         return false;
 
+      APInt DemandedBits = APInt::getZero(EltSizeInBits);
       APInt DemandedElts = APInt::getZero(NumElts);
       for (int I = 0; I != NumElts; ++I)
-        if (!EltBits[I].isZero())
+        if (!EltBits[I].isZero()) {
+          DemandedBits |= EltBits[I];
           DemandedElts.setBit(I);
+        }
 
       APInt KnownUndef, KnownZero;
       return TLI.SimplifyDemandedVectorElts(OtherOp, DemandedElts, KnownUndef,
-                                            KnownZero, DCI);
+                                            KnownZero, DCI) ||
+             TLI.SimplifyDemandedBits(OtherOp, DemandedBits, DemandedElts, DCI);
     };
     if (SimplifyUndemandedElts(N0, N1) || SimplifyUndemandedElts(N1, N0)) {
       if (N->getOpcode() != ISD::DELETED_NODE)

diff  --git a/llvm/test/CodeGen/X86/vector_splat-const-shift-of-constmasked.ll b/llvm/test/CodeGen/X86/vector_splat-const-shift-of-constmasked.ll
index d751fc7ec0029..608522e888148 100644
--- a/llvm/test/CodeGen/X86/vector_splat-const-shift-of-constmasked.ll
+++ b/llvm/test/CodeGen/X86/vector_splat-const-shift-of-constmasked.ll
@@ -3062,7 +3062,6 @@ define <2 x i64> @test_128_i64_x_2_140737488289792_mask_ashr_18(<2 x i64> %a0) {
 define <2 x i64> @test_128_i64_x_2_18446744065119617024_mask_ashr_1(<2 x i64> %a0) {
 ; X86-SSE2-LABEL: test_128_i64_x_2_18446744065119617024_mask_ashr_1:
 ; X86-SSE2:       # %bb.0:
-; X86-SSE2-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}, %xmm0
 ; X86-SSE2-NEXT:    psrad $1, %xmm0
 ; X86-SSE2-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}, %xmm0
 ; X86-SSE2-NEXT:    retl
@@ -3086,7 +3085,6 @@ define <2 x i64> @test_128_i64_x_2_18446744065119617024_mask_ashr_1(<2 x i64> %a
 ;
 ; X64-SSE2-LABEL: test_128_i64_x_2_18446744065119617024_mask_ashr_1:
 ; X64-SSE2:       # %bb.0:
-; X64-SSE2-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
 ; X64-SSE2-NEXT:    psrad $1, %xmm0
 ; X64-SSE2-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
 ; X64-SSE2-NEXT:    retq