Revert "[DAG] Fold shuffle(bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d)))"

This reverts commit 5dfba562dd247f731528448ee83785b099f93629.

That commit causes an assertion failure with the following repro:

typedef long b __attribute__((__vector_size__(16)));
b *d;
b e;
b __attribute__((__always_inline__)) c(b h, b i) {
  return (__attribute__((__vector_size__(8 * sizeof(short)))) short)h + i;
}
j() {
  b k, l, m, n, o[6], p, q;
  m = d[5];
  b r = m;
  b s = f(r, 8);
  q = s;
  l = d[1];
  p = l;
  t(q);
  n = c(m, l);
  o[1] = c(s, f(p, 8));
  k = __builtin_shufflevector(n, o[1], 0, 2);
  e = __builtin_ia32_psrlwi128(k, j);
}

./bin/clang -cc1 -triple x86_64-grtev4-linux-gnu -emit-obj -O1 -std=c99 test.c

lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -20919,13 +20919,11 @@ SDValue DAGCombiner::visitVECTOR_SHUFFLE(SDNode *N) {
 
   // Compute the combined shuffle mask for a shuffle with SV0 as the first
   // operand, and SV1 as the second operand.
-  // i.e. Merge SVN(OtherSVN, N1) -> shuffle(SV0, SV1, Mask) iff Commute = false
+  // i.e. Merge SVN(OtherSVN, N1) -> shuffle(SV0, SV1, Mask).
-  //      Merge SVN(N1, OtherSVN) -> shuffle(SV0, SV1, Mask') iff Commute = true
   auto MergeInnerShuffle =
-      [NumElts, &VT](bool Commute, ShuffleVectorSDNode *SVN,
+      [NumElts, &VT](ShuffleVectorSDNode *SVN, ShuffleVectorSDNode *OtherSVN,
-                     ShuffleVectorSDNode *OtherSVN, SDValue N1,
+                     SDValue N1, const TargetLowering &TLI, SDValue &SV0,
-                     const TargetLowering &TLI, SDValue &SV0, SDValue &SV1,
+                     SDValue &SV1, SmallVectorImpl<int> &Mask) -> bool {
-                     SmallVectorImpl<int> &Mask) -> bool {
     // Don't try to fold splats; they're likely to simplify somehow, or they
     // might be free.
     if (OtherSVN->isSplat())
@@ -20942,9 +20940,6 @@ SDValue DAGCombiner::visitVECTOR_SHUFFLE(SDNode *N) {
         continue;
       }
 
-      if (Commute)
-        Idx = (Idx < (int)NumElts) ? (Idx + NumElts) : (Idx - NumElts);
-
       SDValue CurrentVec;
       if (Idx < (int)NumElts) {
         // This shuffle index refers to the inner shuffle N0. Lookup the inner
@@ -21050,7 +21045,7 @@ SDValue DAGCombiner::visitVECTOR_SHUFFLE(SDNode *N) {
 
     SDValue SV0, SV1;
     SmallVector<int, 4> Mask;
-    if (MergeInnerShuffle(false, SVN, OtherSV, N1, TLI, SV0, SV1, Mask)) {
+    if (MergeInnerShuffle(SVN, OtherSV, N1, TLI, SV0, SV1, Mask)) {
       // Check if all indices in Mask are Undef. In case, propagate Undef.
       if (llvm::all_of(Mask, [](int M) { return M < 0; }))
         return DAG.getUNDEF(VT);
@@ -21060,77 +21055,6 @@ SDValue DAGCombiner::visitVECTOR_SHUFFLE(SDNode *N) {
     }
   }
 
-  // Merge shuffles through binops if we are able to merge it with at least one
-  // other shuffles.
-  // shuffle(bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d)))
-  if (Level < AfterLegalizeDAG && TLI.isTypeLegal(VT)) {
-    unsigned SrcOpcode = N0.getOpcode();
-    if (SrcOpcode == N1.getOpcode() && TLI.isBinOp(SrcOpcode) &&
-        N->isOnlyUserOf(N0.getNode()) && N->isOnlyUserOf(N1.getNode())) {
-      SDValue Op00 = N0.getOperand(0);
-      SDValue Op10 = N1.getOperand(0);
-      SDValue Op01 = N0.getOperand(1);
-      SDValue Op11 = N1.getOperand(1);
-      // TODO: We might be able to relax the VT check but we don't currently
-      // have any isBinOp() that has different result/ops VTs so play safe until
-      // we have test coverage.
-      if (Op00.getValueType() == VT && Op10.getValueType() == VT &&
-          Op01.getValueType() == VT && Op11.getValueType() == VT &&
-          (Op00.getOpcode() == ISD::VECTOR_SHUFFLE ||
-           Op10.getOpcode() == ISD::VECTOR_SHUFFLE ||
-           Op01.getOpcode() == ISD::VECTOR_SHUFFLE ||
-           Op11.getOpcode() == ISD::VECTOR_SHUFFLE)) {
-        auto CanMergeInnerShuffle = [&](SDValue &SV0, SDValue &SV1,
-                                        SmallVectorImpl<int> &Mask, bool LeftOp,
-                                        bool Commute) {
-          SDValue InnerN = Commute ? N1 : N0;
-          SDValue Op0 = LeftOp ? Op00 : Op01;
-          SDValue Op1 = LeftOp ? Op10 : Op11;
-          if (Commute)
-            std::swap(Op0, Op1);
-          return Op0.getOpcode() == ISD::VECTOR_SHUFFLE &&
-                 InnerN->isOnlyUserOf(Op0.getNode()) &&
-                 MergeInnerShuffle(Commute, SVN, cast<ShuffleVectorSDNode>(Op0),
-                                   Op1, TLI, SV0, SV1, Mask) &&
-                 llvm::none_of(Mask, [](int M) { return M < 0; });
-        };
-
-        // Ensure we don't increase the number of shuffles - we must merge a
-        // shuffle from at least one of the LHS and RHS ops.
-        bool MergedLeft = false;
-        SDValue LeftSV0, LeftSV1;
-        SmallVector<int, 4> LeftMask;
-        if (CanMergeInnerShuffle(LeftSV0, LeftSV1, LeftMask, true, false) ||
-            CanMergeInnerShuffle(LeftSV0, LeftSV1, LeftMask, true, true)) {
-          MergedLeft = true;
-        } else {
-          LeftMask.assign(SVN->getMask().begin(), SVN->getMask().end());
-          LeftSV0 = Op00, LeftSV1 = Op10;
-        }
-
-        bool MergedRight = false;
-        SDValue RightSV0, RightSV1;
-        SmallVector<int, 4> RightMask;
-        if (CanMergeInnerShuffle(RightSV0, RightSV1, RightMask, false, false) ||
-            CanMergeInnerShuffle(RightSV0, RightSV1, RightMask, false, true)) {
-          MergedRight = true;
-        } else {
-          RightMask.assign(SVN->getMask().begin(), SVN->getMask().end());
-          RightSV0 = Op01, RightSV1 = Op11;
-        }
-
-        if (MergedLeft || MergedRight) {
-          SDLoc DL(N);
-          SDValue LHS =
-              DAG.getVectorShuffle(VT, DL, LeftSV0, LeftSV1, LeftMask);
-          SDValue RHS =
-              DAG.getVectorShuffle(VT, DL, RightSV0, RightSV1, RightMask);
-          return DAG.getNode(SrcOpcode, DL, VT, LHS, RHS);
-        }
-      }
-    }
-  }
-
   if (SDValue V = foldShuffleOfConcatUndefs(SVN, DAG))
     return V;
 

lib/Target/X86/X86ISelLowering.cpp

@@ -38029,6 +38029,34 @@ static SDValue combineShuffle(SDNode *N, SelectionDAG &DAG,
 
     if (SDValue HAddSub = foldShuffleOfHorizOp(N, DAG))
       return HAddSub;
+
+    // Merge shuffles through binops if its likely we'll be able to merge it
+    // with other shuffles (as long as they aren't splats).
+    // shuffle(bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d)))
+    // TODO: We might be able to move this to DAGCombiner::visitVECTOR_SHUFFLE.
+    if (auto *SVN = dyn_cast<ShuffleVectorSDNode>(N)) {
+      unsigned SrcOpcode = N->getOperand(0).getOpcode();
+      if (SrcOpcode == N->getOperand(1).getOpcode() && TLI.isBinOp(SrcOpcode) &&
+          N->isOnlyUserOf(N->getOperand(0).getNode()) &&
+          N->isOnlyUserOf(N->getOperand(1).getNode())) {
+        SDValue Op00 = N->getOperand(0).getOperand(0);
+        SDValue Op10 = N->getOperand(1).getOperand(0);
+        SDValue Op01 = N->getOperand(0).getOperand(1);
+        SDValue Op11 = N->getOperand(1).getOperand(1);
+        auto *SVN00 = dyn_cast<ShuffleVectorSDNode>(Op00);
+        auto *SVN10 = dyn_cast<ShuffleVectorSDNode>(Op10);
+        auto *SVN01 = dyn_cast<ShuffleVectorSDNode>(Op01);
+        auto *SVN11 = dyn_cast<ShuffleVectorSDNode>(Op11);
+        if (((SVN00 && !SVN00->isSplat()) || (SVN10 && !SVN10->isSplat())) &&
+            ((SVN01 && !SVN01->isSplat()) || (SVN11 && !SVN11->isSplat()))) {
+          SDLoc DL(N);
+          ArrayRef<int> Mask = SVN->getMask();
+          SDValue LHS = DAG.getVectorShuffle(VT, DL, Op00, Op10, Mask);
+          SDValue RHS = DAG.getVectorShuffle(VT, DL, Op01, Op11, Mask);
+          return DAG.getNode(SrcOpcode, DL, VT, LHS, RHS);
+        }
+      }
+    }
   }
 
   // Attempt to combine into a vector load/broadcast.

test/CodeGen/X86/bitcast-and-setcc-256.ll

@@ -9,41 +9,47 @@
 define i4 @v4i64(<4 x i64> %a, <4 x i64> %b, <4 x i64> %c, <4 x i64> %d) {
 ; SSE2-SSSE3-LABEL: v4i64:
 ; SSE2-SSSE3:       # %bb.0:
-; SSE2-SSSE3-NEXT:    movdqa {{.*#+}} xmm9 = [2147483648,2147483648]
+; SSE2-SSSE3-NEXT:    movdqa {{.*#+}} xmm8 = [2147483648,2147483648]
-; SSE2-SSSE3-NEXT:    pxor %xmm9, %xmm3
+; SSE2-SSSE3-NEXT:    pxor %xmm8, %xmm3
-; SSE2-SSSE3-NEXT:    pxor %xmm9, %xmm1
+; SSE2-SSSE3-NEXT:    pxor %xmm8, %xmm1
-; SSE2-SSSE3-NEXT:    movdqa %xmm1, %xmm10
+; SSE2-SSSE3-NEXT:    movdqa %xmm1, %xmm9
-; SSE2-SSSE3-NEXT:    pcmpgtd %xmm3, %xmm10
+; SSE2-SSSE3-NEXT:    pcmpgtd %xmm3, %xmm9
-; SSE2-SSSE3-NEXT:    pxor %xmm9, %xmm2
-; SSE2-SSSE3-NEXT:    pxor %xmm9, %xmm0
-; SSE2-SSSE3-NEXT:    movdqa %xmm0, %xmm8
-; SSE2-SSSE3-NEXT:    pcmpgtd %xmm2, %xmm8
-; SSE2-SSSE3-NEXT:    movdqa %xmm8, %xmm11
-; SSE2-SSSE3-NEXT:    shufps {{.*#+}} xmm11 = xmm11[0,2],xmm10[0,2]
 ; SSE2-SSSE3-NEXT:    pcmpeqd %xmm3, %xmm1
+; SSE2-SSSE3-NEXT:    pshufd {{.*#+}} xmm1 = xmm1[1,1,3,3]
+; SSE2-SSSE3-NEXT:    pand %xmm9, %xmm1
+; SSE2-SSSE3-NEXT:    pshufd {{.*#+}} xmm3 = xmm9[1,1,3,3]
+; SSE2-SSSE3-NEXT:    por %xmm1, %xmm3
+; SSE2-SSSE3-NEXT:    pxor %xmm8, %xmm2
+; SSE2-SSSE3-NEXT:    pxor %xmm8, %xmm0
+; SSE2-SSSE3-NEXT:    movdqa %xmm0, %xmm1
+; SSE2-SSSE3-NEXT:    pcmpgtd %xmm2, %xmm1
 ; SSE2-SSSE3-NEXT:    pcmpeqd %xmm2, %xmm0
-; SSE2-SSSE3-NEXT:    shufps {{.*#+}} xmm0 = xmm0[1,3],xmm1[1,3]
+; SSE2-SSSE3-NEXT:    pshufd {{.*#+}} xmm2 = xmm0[1,1,3,3]
-; SSE2-SSSE3-NEXT:    andps %xmm11, %xmm0
+; SSE2-SSSE3-NEXT:    pand %xmm1, %xmm2
-; SSE2-SSSE3-NEXT:    shufps {{.*#+}} xmm8 = xmm8[1,3],xmm10[1,3]
+; SSE2-SSSE3-NEXT:    pshufd {{.*#+}} xmm0 = xmm1[1,1,3,3]
-; SSE2-SSSE3-NEXT:    orps %xmm0, %xmm8
+; SSE2-SSSE3-NEXT:    por %xmm2, %xmm0
-; SSE2-SSSE3-NEXT:    pxor %xmm9, %xmm7
+; SSE2-SSSE3-NEXT:    shufps {{.*#+}} xmm0 = xmm0[0,2],xmm3[0,2]
-; SSE2-SSSE3-NEXT:    pxor %xmm9, %xmm5
+; SSE2-SSSE3-NEXT:    pxor %xmm8, %xmm7
-; SSE2-SSSE3-NEXT:    movdqa %xmm5, %xmm0
+; SSE2-SSSE3-NEXT:    pxor %xmm8, %xmm5
-; SSE2-SSSE3-NEXT:    pcmpgtd %xmm7, %xmm0
+; SSE2-SSSE3-NEXT:    movdqa %xmm5, %xmm1
-; SSE2-SSSE3-NEXT:    pxor %xmm9, %xmm6
+; SSE2-SSSE3-NEXT:    pcmpgtd %xmm7, %xmm1
-; SSE2-SSSE3-NEXT:    pxor %xmm9, %xmm4
-; SSE2-SSSE3-NEXT:    movdqa %xmm4, %xmm1
-; SSE2-SSSE3-NEXT:    pcmpgtd %xmm6, %xmm1
-; SSE2-SSSE3-NEXT:    movdqa %xmm1, %xmm2
-; SSE2-SSSE3-NEXT:    shufps {{.*#+}} xmm2 = xmm2[0,2],xmm0[0,2]
 ; SSE2-SSSE3-NEXT:    pcmpeqd %xmm7, %xmm5
+; SSE2-SSSE3-NEXT:    pshufd {{.*#+}} xmm2 = xmm5[1,1,3,3]
+; SSE2-SSSE3-NEXT:    pand %xmm1, %xmm2
+; SSE2-SSSE3-NEXT:    pshufd {{.*#+}} xmm1 = xmm1[1,1,3,3]
+; SSE2-SSSE3-NEXT:    por %xmm2, %xmm1
+; SSE2-SSSE3-NEXT:    pxor %xmm8, %xmm6
+; SSE2-SSSE3-NEXT:    pxor %xmm8, %xmm4
+; SSE2-SSSE3-NEXT:    movdqa %xmm4, %xmm2
+; SSE2-SSSE3-NEXT:    pcmpgtd %xmm6, %xmm2
 ; SSE2-SSSE3-NEXT:    pcmpeqd %xmm6, %xmm4
-; SSE2-SSSE3-NEXT:    shufps {{.*#+}} xmm4 = xmm4[1,3],xmm5[1,3]
+; SSE2-SSSE3-NEXT:    pshufd {{.*#+}} xmm3 = xmm4[1,1,3,3]
-; SSE2-SSSE3-NEXT:    andps %xmm2, %xmm4
+; SSE2-SSSE3-NEXT:    pand %xmm2, %xmm3
-; SSE2-SSSE3-NEXT:    shufps {{.*#+}} xmm1 = xmm1[1,3],xmm0[1,3]
+; SSE2-SSSE3-NEXT:    pshufd {{.*#+}} xmm2 = xmm2[1,1,3,3]
-; SSE2-SSSE3-NEXT:    orps %xmm4, %xmm1
+; SSE2-SSSE3-NEXT:    por %xmm3, %xmm2
-; SSE2-SSSE3-NEXT:    andps %xmm8, %xmm1
+; SSE2-SSSE3-NEXT:    shufps {{.*#+}} xmm2 = xmm2[0,2],xmm1[0,2]
-; SSE2-SSSE3-NEXT:    movmskps %xmm1, %eax
+; SSE2-SSSE3-NEXT:    andps %xmm0, %xmm2
+; SSE2-SSSE3-NEXT:    movmskps %xmm2, %eax
 ; SSE2-SSSE3-NEXT:    # kill: def $al killed $al killed $eax
 ; SSE2-SSSE3-NEXT:    retq
 ;

test/CodeGen/X86/promote-cmp.ll

@@ -8,34 +8,36 @@ define <4 x i64> @PR45808(<4 x i64> %0, <4 x i64> %1) {
 ; SSE2-LABEL: PR45808:
 ; SSE2:       # %bb.0:
 ; SSE2-NEXT:    movdqa {{.*#+}} xmm4 = [2147483648,2147483648]
-; SSE2-NEXT:    movdqa %xmm3, %xmm9
+; SSE2-NEXT:    movdqa %xmm3, %xmm5
-; SSE2-NEXT:    pxor %xmm4, %xmm9
+; SSE2-NEXT:    pxor %xmm4, %xmm5
 ; SSE2-NEXT:    movdqa %xmm1, %xmm6
 ; SSE2-NEXT:    pxor %xmm4, %xmm6
-; SSE2-NEXT:    movdqa %xmm6, %xmm8
+; SSE2-NEXT:    movdqa %xmm6, %xmm7
-; SSE2-NEXT:    pcmpgtd %xmm9, %xmm8
+; SSE2-NEXT:    pcmpgtd %xmm5, %xmm7
-; SSE2-NEXT:    movdqa %xmm2, %xmm7
+; SSE2-NEXT:    pcmpeqd %xmm5, %xmm6
-; SSE2-NEXT:    pxor %xmm4, %xmm7
+; SSE2-NEXT:    pshufd {{.*#+}} xmm5 = xmm6[1,1,3,3]
+; SSE2-NEXT:    pand %xmm7, %xmm5
+; SSE2-NEXT:    pshufd {{.*#+}} xmm6 = xmm7[1,1,3,3]
+; SSE2-NEXT:    por %xmm5, %xmm6
+; SSE2-NEXT:    movdqa %xmm2, %xmm5
+; SSE2-NEXT:    pxor %xmm4, %xmm5
 ; SSE2-NEXT:    pxor %xmm0, %xmm4
-; SSE2-NEXT:    movdqa %xmm4, %xmm5
+; SSE2-NEXT:    movdqa %xmm4, %xmm7
-; SSE2-NEXT:    pcmpgtd %xmm7, %xmm5
+; SSE2-NEXT:    pcmpgtd %xmm5, %xmm7
-; SSE2-NEXT:    movdqa %xmm5, %xmm10
+; SSE2-NEXT:    pcmpeqd %xmm5, %xmm4
-; SSE2-NEXT:    shufps {{.*#+}} xmm10 = xmm10[0,2],xmm8[0,2]
-; SSE2-NEXT:    pcmpeqd %xmm9, %xmm6
-; SSE2-NEXT:    pcmpeqd %xmm7, %xmm4
-; SSE2-NEXT:    shufps {{.*#+}} xmm4 = xmm4[1,3],xmm6[1,3]
-; SSE2-NEXT:    andps %xmm10, %xmm4
-; SSE2-NEXT:    shufps {{.*#+}} xmm5 = xmm5[1,3],xmm8[1,3]
-; SSE2-NEXT:    orps %xmm4, %xmm5
-; SSE2-NEXT:    pshufd {{.*#+}} xmm4 = xmm5[2,1,3,3]
-; SSE2-NEXT:    pxor {{.*}}(%rip), %xmm5
-; SSE2-NEXT:    psllq $63, %xmm4
-; SSE2-NEXT:    psrad $31, %xmm4
 ; SSE2-NEXT:    pshufd {{.*#+}} xmm4 = xmm4[1,1,3,3]
-; SSE2-NEXT:    pand %xmm4, %xmm1
+; SSE2-NEXT:    pand %xmm7, %xmm4
-; SSE2-NEXT:    pandn %xmm3, %xmm4
+; SSE2-NEXT:    pshufd {{.*#+}} xmm5 = xmm7[1,1,3,3]
-; SSE2-NEXT:    por %xmm4, %xmm1
+; SSE2-NEXT:    por %xmm4, %xmm5
-; SSE2-NEXT:    pshufd {{.*#+}} xmm3 = xmm5[0,1,1,3]
+; SSE2-NEXT:    pshufd {{.*#+}} xmm4 = xmm5[0,2,2,3]
+; SSE2-NEXT:    pxor {{.*}}(%rip), %xmm4
+; SSE2-NEXT:    psllq $63, %xmm6
+; SSE2-NEXT:    psrad $31, %xmm6
+; SSE2-NEXT:    pshufd {{.*#+}} xmm5 = xmm6[1,1,3,3]
+; SSE2-NEXT:    pand %xmm5, %xmm1
+; SSE2-NEXT:    pandn %xmm3, %xmm5
+; SSE2-NEXT:    por %xmm5, %xmm1
+; SSE2-NEXT:    pshufd {{.*#+}} xmm3 = xmm4[0,1,1,3]
 ; SSE2-NEXT:    psllq $63, %xmm3
 ; SSE2-NEXT:    psrad $31, %xmm3
 ; SSE2-NEXT:    pshufd {{.*#+}} xmm3 = xmm3[1,1,3,3]