[SLP]Prefer instructions, ued outside the block, as the initial main copyable instructions

Instructions, used outside the block, must be considered the first
choice for the main instructionsin the copyable nodes, to avoid
use-before-def.

Fixes #171055

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -10930,13 +10930,21 @@ class InstructionsCompatibilityAnalysis {
     }
     unsigned BestOpcodeNum = 0;
     MainOp = nullptr;
+    bool UsedOutside = false;
     for (const auto &P : Candidates) {
+      bool PUsedOutside = all_of(P.second, isUsedOutsideBlock);
+      if (UsedOutside && !PUsedOutside)
+        continue;
+      if (!UsedOutside && PUsedOutside)
+        BestOpcodeNum = 0;
       if (P.second.size() < BestOpcodeNum)
         continue;
       // If have inner dependencies - skip.
-      if (any_of(P.second,
-                 [&](Instruction *I) { return Operands.contains(I); }))
+      if (!PUsedOutside && any_of(P.second, [&](Instruction *I) {
+            return Operands.contains(I);
+          }))
         continue;
+      UsedOutside = PUsedOutside;
       for (Instruction *I : P.second) {
         if (IsSupportedInstruction(I, AnyUndef)) {
           MainOp = I;

llvm/test/Transforms/SLPVectorizer/X86/copyable-child-node-used-outside.ll

@@ -8,10 +8,9 @@ define <4 x i32> @test() {
 ; CHECK-NEXT:    br label %[[BB1:.*]]
 ; CHECK:       [[BB1]]:
 ; CHECK-NEXT:    [[OR:%.*]] = or i32 [[TRUNC]], 0
-; CHECK-NEXT:    [[TMP0:%.*]] = insertelement <4 x i32> poison, i32 [[TRUNC]], i32 0
-; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <4 x i32> [[TMP0]], i32 0, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <4 x i32> <i32 poison, i32 0, i32 poison, i32 poison>, i32 [[TRUNC]], i32 0
 ; CHECK-NEXT:    [[TMP2:%.*]] = shufflevector <4 x i32> [[TMP1]], <4 x i32> poison, <4 x i32> <i32 0, i32 1, i32 0, i32 0>
-; CHECK-NEXT:    [[TMP3:%.*]] = or <4 x i32> [[TMP2]], zeroinitializer
+; CHECK-NEXT:    [[TMP3:%.*]] = and <4 x i32> <i32 -1, i32 0, i32 0, i32 0>, [[TMP2]]
 ; CHECK-NEXT:    [[ZEXT:%.*]] = zext i32 [[OR]] to i64
 ; CHECK-NEXT:    br label %[[BB3:.*]]
 ; CHECK:       [[BB3]]:

llvm/test/Transforms/SLPVectorizer/X86/copyable-with-used-outside-bb.ll

@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: opt -S --passes=slp-vectorizer -mtriple=x86_64-unknown-linux-gnu -slp-threshold=-99999 < %s | FileCheck %s
+
+define void @test(i32 %arg) {
+; CHECK-LABEL: define void @test(
+; CHECK-SAME: i32 [[ARG:%.*]]) {
+; CHECK-NEXT:  [[BB:.*:]]
+; CHECK-NEXT:    br label %[[BB1:.*]]
+; CHECK:       [[BB1]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = insertelement <4 x i32> <i32 0, i32 0, i32 poison, i32 0>, i32 [[ARG]], i32 2
+; CHECK-NEXT:    [[TMP1:%.*]] = sub <4 x i32> <i32 7, i32 7, i32 0, i32 7>, [[TMP0]]
+; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <4 x i32> [[TMP1]], i32 0
+; CHECK-NEXT:    [[ICMP:%.*]] = icmp ult i32 [[TMP2]], 0
+; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <4 x i32> [[TMP1]], <4 x i32> <i32 poison, i32 0, i32 poison, i32 0>, <4 x i32> <i32 0, i32 5, i32 2, i32 7>
+; CHECK-NEXT:    br i1 false, label %[[BB2:.*]], label %[[BB3:.*]]
+; CHECK:       [[BB2]]:
+; CHECK-NEXT:    br label %[[BB3]]
+; CHECK:       [[BB3]]:
+; CHECK-NEXT:    [[TMP4:%.*]] = phi <4 x i32> [ [[TMP1]], %[[BB2]] ], [ [[TMP3]], %[[BB1]] ]
+; CHECK-NEXT:    ret void
+;
+bb:
+  br label %bb1
+
+bb1:
+  %sub = sub i32 0, %arg
+  %add = add i32 7, 0
+  %icmp = icmp ult i32 %add, 0
+  br i1 false, label %bb2, label %bb3
+
+bb2:
+  br label %bb3
+
+bb3:
+  %phi = phi i32 [ 7, %bb2 ], [ 0, %bb1 ]
+  %phi4 = phi i32 [ %sub, %bb2 ], [ %sub, %bb1 ]
+  %phi5 = phi i32 [ %add, %bb2 ], [ %add, %bb1 ]
+  %phi6 = phi i32 [ %add, %bb2 ], [ 0, %bb1 ]
+  ret void
+}