[SLP]Fix PHI comparator to make it follow weak strict ordering restriction

Fixes llvm#137164

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -23979,6 +23979,8 @@ bool SLPVectorizerPass::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
     assert(isValidElementType(V1->getType()) &&
            isValidElementType(V2->getType()) &&
            "Expected vectorizable types only.");
+    if (V1 == V2)
+      return false;
     // It is fine to compare type IDs here, since we expect only vectorizable
     // types, like ints, floats and pointers, we don't care about other type.
     if (V1->getType()->getTypeID() < V2->getType()->getTypeID())
@@ -24015,7 +24017,7 @@ bool SLPVectorizerPass::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
           if (NodeI1 != NodeI2)
             return NodeI1->getDFSNumIn() < NodeI2->getDFSNumIn();
           InstructionsState S = getSameOpcode({I1, I2}, *TLI);
-          if (S && !S.isAltShuffle()) {
+          if (S && !S.isAltShuffle() && I1->getOpcode() == I2->getOpcode()) {
             const auto *E1 = dyn_cast<ExtractElementInst>(I1);
             const auto *E2 = dyn_cast<ExtractElementInst>(I2);
             if (!E1 || !E2)
@@ -24047,6 +24049,8 @@ bool SLPVectorizerPass::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
 
             continue;
           }
+          if (I1->getOpcode() == I2->getOpcode())
+            continue;
           return I1->getOpcode() < I2->getOpcode();
         }
         if (I1)

llvm/test/Transforms/SLPVectorizer/X86/phi-comparator.ll

@@ -0,0 +1,38 @@
+; 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 < %s | FileCheck %s
+
+define void @test(i32 %julianDay, i1 %cmp, i8 %0, i16 %1) {
+; CHECK-LABEL: define void @test(
+; CHECK-SAME: i32 [[JULIANDAY:%.*]], i1 [[CMP:%.*]], i8 [[TMP0:%.*]], i16 [[TMP1:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br i1 [[CMP]], label %[[IF_THEN2:.*]], label %[[IF_END33:.*]]
+; CHECK:       [[IF_THEN2]]:
+; CHECK-NEXT:    [[CONV_I:%.*]] = sext i8 [[TMP0]] to i32
+; CHECK-NEXT:    [[CONV_I2:%.*]] = sext i16 [[TMP1]] to i32
+; CHECK-NEXT:    br label %[[IF_END33]]
+; CHECK:       [[IF_END33]]:
+; CHECK-NEXT:    [[MONTH_0:%.*]] = phi i32 [ [[CONV_I]], %[[IF_THEN2]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    [[DAYOFMONTH_0:%.*]] = phi i32 [ [[CONV_I]], %[[IF_THEN2]] ], [ [[JULIANDAY]], %[[ENTRY]] ]
+; CHECK-NEXT:    [[DAYOFYEAR_0:%.*]] = phi i32 [ [[CONV_I2]], %[[IF_THEN2]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    store volatile i32 [[MONTH_0]], ptr null, align 4294967296
+; CHECK-NEXT:    store volatile i32 [[DAYOFMONTH_0]], ptr null, align 4294967296
+; CHECK-NEXT:    store volatile i32 [[DAYOFYEAR_0]], ptr null, align 4294967296
+; CHECK-NEXT:    ret void
+;
+entry:
+  br i1 %cmp, label %if.then2, label %if.end33
+
+if.then2:
+  %conv.i = sext i8 %0 to i32
+  %conv.i2 = sext i16 %1 to i32
+  br label %if.end33
+
+if.end33:
+  %month.0 = phi i32 [ %conv.i, %if.then2 ], [ 0, %entry ]
+  %dayOfMonth.0 = phi i32 [ %conv.i, %if.then2 ], [ %julianDay, %entry ]
+  %dayOfYear.0 = phi i32 [ %conv.i2, %if.then2 ], [ 0, %entry ]
+  store volatile i32 %month.0, ptr null, align 4294967296
+  store volatile i32 %dayOfMonth.0, ptr null, align 4294967296
+  store volatile i32 %dayOfYear.0, ptr null, align 4294967296
+  ret void
+}