Revert "[SLP] Check for PHI nodes (potentially cycles!) when checking dependencies"

This reverts commit 2eb558c.

This commit did not pass pre-commit CI.

Author: tstellar

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -13181,16 +13181,8 @@ BoUpSLP::isGatherShuffledSingleRegisterEntry(
           continue;
         // If the user instruction is used for some reason in different
         // vectorized nodes - make it depend on index.
-        // If any vector node is PHI node, this dependency might not work
-        // because of cycle dependencies, so disable it.
         if (TEUseEI.UserTE != UseEI.UserTE &&
-            (TEUseEI.UserTE->Idx < UseEI.UserTE->Idx ||
-             any_of(
-                 VectorizableTree,
-                 [](const std::unique_ptr<TreeEntry> &TE) {
-                   return TE->State == TreeEntry::Vectorize &&
-                          TE->getOpcode() == Instruction::PHI;
-                 })))
+            TEUseEI.UserTE->Idx < UseEI.UserTE->Idx)
           continue;
       }
 

llvm/test/Transforms/SLPVectorizer/X86/delayed-gather-emission.ll

@@ -31,7 +31,7 @@ define void @test() {
 ; CHECK-NEXT:    [[TOBOOL:%.*]] = fcmp une float [[I2]], 0.000000e+00
 ; CHECK-NEXT:    [[TMP8:%.*]] = shufflevector <2 x float> [[TMP5]], <2 x float> poison, <2 x i32> <i32 poison, i32 0>
 ; CHECK-NEXT:    [[TMP9]] = insertelement <2 x float> [[TMP8]], float [[I2]], i32 0
-; CHECK-NEXT:    [[TMP10]] = insertelement <2 x float> [[TMP2]], float [[I2]], i32 0
+; CHECK-NEXT:    [[TMP10]] = shufflevector <2 x float> [[TMP9]], <2 x float> [[TMP2]], <2 x i32> <i32 0, i32 3>
 ; CHECK-NEXT:    br i1 [[TOBOOL]], label [[BB1]], label [[BB2]]
 ;
 entry:

llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll

@@ -8,7 +8,7 @@
 ; YAML: Function:        test
 ; YAML: Args:
 ; YAML:   - String:          'Stores SLP vectorized with cost '
-; YAML:   - Cost:            '-3'
+; YAML:   - Cost:            '-6'
 ; YAML:   - String:          ' and with tree size '
 ; YAML:   - TreeSize:        '14'
 ; YAML: ...