[SLP]Transform nodes before building externally used values

transformNodes function may create new vector nodes, so the reduced
values might be vectorized later. Need to build the list of the
externally used values after the transformNodes() function call to avoid
compiler crash.

Fixe #110787

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -18848,6 +18848,7 @@ class HorizontalReduction {
             ++SameValuesCounter.try_emplace(OrigV).first->second;
           }
         }
+        V.transformNodes();
         SmallPtrSet<Value *, 4> VLScalars(VL.begin(), VL.end());
         // Gather externally used values.
         SmallPtrSet<Value *, 4> Visited;
@@ -18877,7 +18878,6 @@ class HorizontalReduction {
         for (Value *RdxVal : VL)
           if (RequiredExtract.contains(RdxVal))
             LocalExternallyUsedValues[RdxVal];
-        V.transformNodes();
         V.buildExternalUses(LocalExternallyUsedValues);
 
         V.computeMinimumValueSizes();

llvm/test/Transforms/SLPVectorizer/X86/reduced-val-vectorized-in-transform.ll

@@ -0,0 +1,47 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S --passes=slp-vectorizer -mtriple=x86_64-unknown-linux-gnu -slp-threshold=-10 < %s | FileCheck %s
+
+define i32 @test(i1 %cond) {
+; CHECK-LABEL: define i32 @test(
+; CHECK-SAME: i1 [[COND:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br label %[[BB:.*]]
+; CHECK:       [[BB]]:
+; CHECK-NEXT:    [[P1:%.*]] = phi i32 [ [[OR92:%.*]], %[[BB]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = phi <2 x i32> [ [[TMP8:%.*]], %[[BB]] ], [ zeroinitializer, %[[ENTRY]] ]
+; CHECK-NEXT:    [[TMP1:%.*]] = or i32 1, 0
+; CHECK-NEXT:    [[TMP2:%.*]] = shufflevector <2 x i32> [[TMP0]], <2 x i32> poison, <4 x i32> <i32 0, i32 1, i32 poison, i32 poison>
+; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <4 x i32> [[TMP2]], <4 x i32> <i32 poison, i32 poison, i32 0, i32 0>, <4 x i32> <i32 poison, i32 1, i32 6, i32 7>
+; CHECK-NEXT:    [[TMP4:%.*]] = insertelement <4 x i32> [[TMP3]], i32 [[P1]], i32 0
+; CHECK-NEXT:    [[TMP5:%.*]] = or <4 x i32> zeroinitializer, [[TMP4]]
+; CHECK-NEXT:    [[OR92]] = or i32 1, 0
+; CHECK-NEXT:    [[TMP6:%.*]] = call i32 @llvm.vector.reduce.xor.v4i32(<4 x i32> [[TMP5]])
+; CHECK-NEXT:    [[OP_RDX:%.*]] = xor i32 [[TMP6]], [[OR92]]
+; CHECK-NEXT:    [[TMP7:%.*]] = insertelement <2 x i32> poison, i32 [[OP_RDX]], i32 0
+; CHECK-NEXT:    [[TMP8]] = insertelement <2 x i32> [[TMP7]], i32 [[TMP1]], i32 1
+; CHECK-NEXT:    br i1 [[COND]], label %[[EXIT:.*]], label %[[BB]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret i32 [[OP_RDX]]
+;
+entry:
+  br label %bb
+
+bb:
+  %p1 = phi i32 [ %or92, %bb ], [ 0, %entry ]
+  %p2 = phi i32 [ %0, %bb ], [ 0, %entry ]
+  %p3 = phi i32 [ %4, %bb ], [ 0, %entry ]
+  %0 = or i32 1, 0
+  %or8.i = or i32 0, 0
+  %or9.i = or i32 0, 0
+  %or91 = or i32 %p1, 0
+  %or12.i = or i32 %p2, 0
+  %or92 = or i32 1, 0
+  %1 = xor i32 %or91, %or12.i
+  %2 = xor i32 %1, %or9.i
+  %3 = xor i32 %2, %or8.i
+  %4 = xor i32 %3, %or92
+  br i1 %cond, label %exit, label %bb
+
+exit:
+  ret i32 %4
+}