[VPlan] Be more careful with CSE in replicate regions.

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -1979,6 +1979,12 @@ struct VPCSEDenseMapInfo : public DenseMapInfo<VPSingleDefRecipe *> {
         .Case<VPInstruction, VPWidenRecipe, VPWidenCastRecipe,
               VPWidenSelectRecipe, VPWidenGEPRecipe, VPReplicateRecipe>(
             [](auto *I) { return std::make_pair(false, I->getOpcode()); })
+        .Case<VPPredInstPHIRecipe>([](auto *I) {
+          // Treat VPPredInstPHIRecipe as Instruction::PHI for CSE. This is only
+          // safe, if they are in the same block and hence share the same
+          // predicate.
+          return std::make_pair(false, Instruction::PHI);
+        })
         .Case<VPWidenIntrinsicRecipe>([](auto *I) {
           return std::make_pair(true, I->getVectorIntrinsicID());
         })
@@ -2053,6 +2059,15 @@ struct VPCSEDenseMapInfo : public DenseMapInfo<VPSingleDefRecipe *> {
           LFlags->getPredicate() !=
               cast<VPRecipeWithIRFlags>(R)->getPredicate())
         return false;
+    // Recipes in replicate regions implicitly depend on predicate. If either
+    // recipe is in a replicate region, only consider them equal if both have
+    // the same parent.
+    const VPRegionBlock *RegionL = L->getParent()->getParent();
+    const VPRegionBlock *RegionR = R->getParent()->getParent();
+    if (((RegionL && RegionL->isReplicator()) ||
+         (RegionR && RegionR->isReplicator())) &&
+        L->getParent() != R->getParent())
+      return false;
     const VPlan *Plan = L->getParent()->getPlan();
     VPTypeAnalysis TypeInfo(*Plan);
     return TypeInfo.inferScalarType(L) == TypeInfo.inferScalarType(R);

llvm/test/Transforms/LoopVectorize/cse-replicate-regions.ll

@@ -0,0 +1,163 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals none --version 6
+; RUN: opt -p loop-vectorize -force-vector-width=2 -force-widen-divrem-via-safe-divisor=false -S %s | FileCheck %s
+
+define void @multiple_vppredinstphi_with_same_predicate(ptr %A, i32 %d) {
+; CHECK-LABEL: define void @multiple_vppredinstphi_with_same_predicate(
+; CHECK-SAME: ptr [[A:%.*]], i32 [[D:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    br label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_SDIV_CONTINUE2:.*]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr inbounds i32, ptr [[A]], i32 [[INDEX]]
+; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP0]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt <2 x i32> [[WIDE_LOAD]], zeroinitializer
+; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <2 x i1> [[TMP1]], i32 0
+; CHECK-NEXT:    br i1 [[TMP2]], label %[[PRED_SDIV_IF:.*]], label %[[PRED_SDIV_CONTINUE:.*]]
+; CHECK:       [[PRED_SDIV_IF]]:
+; CHECK-NEXT:    [[TMP3:%.*]] = sdiv i32 -10, [[D]]
+; CHECK-NEXT:    [[TMP4:%.*]] = insertelement <2 x i32> poison, i32 [[TMP3]], i32 0
+; CHECK-NEXT:    br label %[[PRED_SDIV_CONTINUE]]
+; CHECK:       [[PRED_SDIV_CONTINUE]]:
+; CHECK-NEXT:    [[TMP5:%.*]] = phi <2 x i32> [ poison, %[[VECTOR_BODY]] ], [ [[TMP4]], %[[PRED_SDIV_IF]] ]
+; CHECK-NEXT:    [[TMP6:%.*]] = extractelement <2 x i1> [[TMP1]], i32 1
+; CHECK-NEXT:    br i1 [[TMP6]], label %[[PRED_SDIV_IF1:.*]], label %[[PRED_SDIV_CONTINUE2]]
+; CHECK:       [[PRED_SDIV_IF1]]:
+; CHECK-NEXT:    [[TMP7:%.*]] = sdiv i32 -10, [[D]]
+; CHECK-NEXT:    [[TMP8:%.*]] = insertelement <2 x i32> [[TMP5]], i32 [[TMP7]], i32 1
+; CHECK-NEXT:    br label %[[PRED_SDIV_CONTINUE2]]
+; CHECK:       [[PRED_SDIV_CONTINUE2]]:
+; CHECK-NEXT:    [[TMP9:%.*]] = phi <2 x i32> [ [[TMP5]], %[[PRED_SDIV_CONTINUE]] ], [ [[TMP8]], %[[PRED_SDIV_IF1]] ]
+; CHECK-NEXT:    [[TMP10:%.*]] = add <2 x i32> [[TMP9]], [[TMP9]]
+; CHECK-NEXT:    [[PREDPHI:%.*]] = select <2 x i1> [[TMP1]], <2 x i32> [[TMP10]], <2 x i32> zeroinitializer
+; CHECK-NEXT:    store <2 x i32> [[PREDPHI]], ptr [[TMP0]], align 4
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 2
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i32 [[INDEX_NEXT]], 100
+; CHECK-NEXT:    br i1 [[TMP11]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    br label %[[EXIT:.*]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop.header
+
+loop.header:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop.latch ]
+  %gep.A = getelementptr inbounds i32, ptr %A, i32 %iv
+  %l = load i32, ptr %gep.A
+  %c = icmp sgt i32 %l, 0
+  br i1 %c, label %then, label %loop.latch
+
+then:
+  %div.0 = sdiv i32 -10, %d
+  %div.1 = sdiv i32 -10, %d
+  %add  = add i32 %div.1, %div.0
+  br label %loop.latch
+
+loop.latch:
+  %merge = phi i32 [ %add, %then ], [ 0, %loop.header ]
+  store i32 %merge, ptr %gep.A
+  %iv.next = add i32 %iv, 1
+  %ec = icmp eq i32 %iv.next, 100
+  br i1 %ec, label %exit, label %loop.header
+
+exit:
+  ret void
+}
+
+define void @multiple_vppredinstphi_with_different_predicate(ptr %A, i32 %d) {
+; CHECK-LABEL: define void @multiple_vppredinstphi_with_different_predicate(
+; CHECK-SAME: ptr [[A:%.*]], i32 [[D:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    br label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_SDIV_CONTINUE6:.*]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr inbounds i32, ptr [[A]], i32 [[INDEX]]
+; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP0]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt <2 x i32> [[WIDE_LOAD]], zeroinitializer
+; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <2 x i1> [[TMP1]], i32 0
+; CHECK-NEXT:    br i1 [[TMP2]], label %[[PRED_SDIV_IF:.*]], label %[[PRED_SDIV_CONTINUE:.*]]
+; CHECK:       [[PRED_SDIV_IF]]:
+; CHECK-NEXT:    [[TMP3:%.*]] = sdiv i32 -10, [[D]]
+; CHECK-NEXT:    [[TMP4:%.*]] = insertelement <2 x i32> poison, i32 [[TMP3]], i32 0
+; CHECK-NEXT:    br label %[[PRED_SDIV_CONTINUE]]
+; CHECK:       [[PRED_SDIV_CONTINUE]]:
+; CHECK-NEXT:    [[TMP5:%.*]] = phi <2 x i32> [ poison, %[[VECTOR_BODY]] ], [ [[TMP4]], %[[PRED_SDIV_IF]] ]
+; CHECK-NEXT:    [[TMP6:%.*]] = extractelement <2 x i1> [[TMP1]], i32 1
+; CHECK-NEXT:    br i1 [[TMP6]], label %[[PRED_SDIV_IF1:.*]], label %[[PRED_SDIV_CONTINUE2:.*]]
+; CHECK:       [[PRED_SDIV_IF1]]:
+; CHECK-NEXT:    [[TMP7:%.*]] = sdiv i32 -10, [[D]]
+; CHECK-NEXT:    [[TMP8:%.*]] = insertelement <2 x i32> [[TMP5]], i32 [[TMP7]], i32 1
+; CHECK-NEXT:    br label %[[PRED_SDIV_CONTINUE2]]
+; CHECK:       [[PRED_SDIV_CONTINUE2]]:
+; CHECK-NEXT:    [[TMP9:%.*]] = phi <2 x i32> [ [[TMP5]], %[[PRED_SDIV_CONTINUE]] ], [ [[TMP8]], %[[PRED_SDIV_IF1]] ]
+; CHECK-NEXT:    [[TMP10:%.*]] = xor <2 x i1> [[TMP1]], splat (i1 true)
+; CHECK-NEXT:    [[TMP11:%.*]] = or <2 x i1> [[TMP1]], [[TMP10]]
+; CHECK-NEXT:    [[PREDPHI:%.*]] = select <2 x i1> [[TMP1]], <2 x i32> [[TMP9]], <2 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp sgt <2 x i32> [[WIDE_LOAD]], splat (i32 20)
+; CHECK-NEXT:    [[TMP13:%.*]] = select <2 x i1> [[TMP11]], <2 x i1> [[TMP12]], <2 x i1> zeroinitializer
+; CHECK-NEXT:    [[TMP14:%.*]] = extractelement <2 x i1> [[TMP13]], i32 0
+; CHECK-NEXT:    br i1 [[TMP14]], label %[[PRED_SDIV_IF3:.*]], label %[[PRED_SDIV_CONTINUE4:.*]]
+; CHECK:       [[PRED_SDIV_IF3]]:
+; CHECK-NEXT:    [[TMP15:%.*]] = sdiv i32 -10, [[D]]
+; CHECK-NEXT:    [[TMP16:%.*]] = insertelement <2 x i32> poison, i32 [[TMP15]], i32 0
+; CHECK-NEXT:    br label %[[PRED_SDIV_CONTINUE4]]
+; CHECK:       [[PRED_SDIV_CONTINUE4]]:
+; CHECK-NEXT:    [[TMP17:%.*]] = phi <2 x i32> [ poison, %[[PRED_SDIV_CONTINUE2]] ], [ [[TMP16]], %[[PRED_SDIV_IF3]] ]
+; CHECK-NEXT:    [[TMP18:%.*]] = extractelement <2 x i1> [[TMP13]], i32 1
+; CHECK-NEXT:    br i1 [[TMP18]], label %[[PRED_SDIV_IF5:.*]], label %[[PRED_SDIV_CONTINUE6]]
+; CHECK:       [[PRED_SDIV_IF5]]:
+; CHECK-NEXT:    [[TMP19:%.*]] = sdiv i32 -10, [[D]]
+; CHECK-NEXT:    [[TMP20:%.*]] = insertelement <2 x i32> [[TMP17]], i32 [[TMP19]], i32 1
+; CHECK-NEXT:    br label %[[PRED_SDIV_CONTINUE6]]
+; CHECK:       [[PRED_SDIV_CONTINUE6]]:
+; CHECK-NEXT:    [[TMP21:%.*]] = phi <2 x i32> [ [[TMP17]], %[[PRED_SDIV_CONTINUE4]] ], [ [[TMP20]], %[[PRED_SDIV_IF5]] ]
+; CHECK-NEXT:    [[PREDPHI7:%.*]] = select <2 x i1> [[TMP12]], <2 x i32> [[TMP21]], <2 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP22:%.*]] = add <2 x i32> [[PREDPHI]], [[PREDPHI7]]
+; CHECK-NEXT:    store <2 x i32> [[TMP22]], ptr [[TMP0]], align 4
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 2
+; CHECK-NEXT:    [[TMP23:%.*]] = icmp eq i32 [[INDEX_NEXT]], 100
+; CHECK-NEXT:    br i1 [[TMP23]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP3:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    br label %[[EXIT:.*]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop.header
+
+loop.header:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop.latch ]
+  %gep.A = getelementptr inbounds i32, ptr %A, i32 %iv
+  %l = load i32, ptr %gep.A
+  %c.0 = icmp sgt i32 %l, 0
+  br i1 %c.0, label %then.0, label %continue
+
+then.0:
+  %div.0 = sdiv i32 -10, %d
+  br label %continue
+
+continue:
+  %merge.0 = phi i32 [ %div.0, %then.0 ], [ 0, %loop.header ]
+  %c.1 = icmp sgt i32 %l, 20
+  br i1 %c.1, label %then.1, label %loop.latch
+
+then.1:
+  %div.1 = sdiv i32 -10, %d
+  br label %loop.latch
+
+loop.latch:
+  %merge.1 = phi i32 [ %div.1, %then.1 ], [ 0, %continue ]
+  %add = add i32 %merge.0, %merge.1
+  store i32 %add, ptr %gep.A
+  %iv.next = add i32 %iv, 1
+  %ec = icmp eq i32 %iv.next, 100
+  br i1 %ec, label %exit, label %loop.header
+
+exit:
+  ret void
+}