[llvm] r219617 - Fix a broadcast related regression on the vector shuffle lowering.

[Filipe Cabecinhas]

Author: filcab
Date: Mon Oct 13 11:16:16 2014
New Revision: 219617

URL: http://llvm.org/viewvc/llvm-project?rev=219617&view=rev
Log:
Fix a broadcast related regression on the vector shuffle lowering.

Summary: Test by Robert Lougher!

Reviewers: chandlerc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5745

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
    llvm/trunk/test/CodeGen/X86/vector-shuffle-256-v4.ll
    llvm/trunk/test/CodeGen/X86/vector-shuffle-256-v8.ll

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=219617&r1=219616&r2=219617&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Mon Oct 13 11:16:16 2014
@@ -7895,10 +7895,42 @@ static SDValue lowerVectorShuffleAsBroad
                                             "a sorted mask where the broadcast "
                                             "comes from V1.");
 
-  // Check if this is a broadcast of a scalar. We special case lowering for
-  // scalars so that we can more effectively fold with loads.
+  // Go up the chain of (vector) values to try and find a scalar load that
+  // we can combine with the broadcast.
+  for (;;) {
+    switch (V.getOpcode()) {
+    case ISD::CONCAT_VECTORS: {
+      int OperandSize = Mask.size() / V.getNumOperands();
+      V = V.getOperand(BroadcastIdx / OperandSize);
+      BroadcastIdx %= OperandSize;
+      continue;
+    }
+
+    case ISD::INSERT_SUBVECTOR: {
+      SDValue VOuter = V.getOperand(0), VInner = V.getOperand(1);
+      auto ConstantIdx = dyn_cast<ConstantSDNode>(V.getOperand(2));
+      if (!ConstantIdx)
+        break;
+
+      int BeginIdx = (int)ConstantIdx->getZExtValue();
+      int EndIdx =
+          BeginIdx + (int)VInner.getValueType().getVectorNumElements();
+      if (BroadcastIdx >= BeginIdx && BroadcastIdx < EndIdx) {
+        BroadcastIdx -= BeginIdx;
+        V = VInner;
+      } else {
+        V = VOuter;
+      }
+      continue;
+    }
+    }
+    break;
+  }
+
+  // Check if this is a broadcast of a scalar. We special case lowering
+  // for scalars so that we can more effectively fold with loads.
   if (V.getOpcode() == ISD::BUILD_VECTOR ||
-        (V.getOpcode() == ISD::SCALAR_TO_VECTOR && BroadcastIdx == 0)) {
+      (V.getOpcode() == ISD::SCALAR_TO_VECTOR && BroadcastIdx == 0)) {
     V = V.getOperand(BroadcastIdx);
 
     // If the scalar isn't a load we can't broadcast from it in AVX1, only with

Modified: llvm/trunk/test/CodeGen/X86/vector-shuffle-256-v4.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/vector-shuffle-256-v4.ll?rev=219617&r1=219616&r2=219617&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/vector-shuffle-256-v4.ll (original)
+++ llvm/trunk/test/CodeGen/X86/vector-shuffle-256-v4.ll Mon Oct 13 11:16:16 2014
@@ -734,3 +734,29 @@ define <4 x i64> @splat_mem_v4i64(i64* %
   %shuffle = shufflevector <4 x i64> %v, <4 x i64> undef, <4 x i32> <i32 0, i32 0, i32 0, i32 0>
   ret <4 x i64> %shuffle
 }
+
+define <4 x double> @splat_mem_v4f64_2(double* %p) {
+; ALL-LABEL: splat_mem_v4f64_2:
+; ALL:       # BB#0:
+; ALL-NEXT:    vbroadcastsd (%rdi), %ymm0
+; ALL-NEXT:    retq
+  %1 = load double* %p
+  %2 = insertelement <2 x double> undef, double %1, i32 0
+  %3 = shufflevector <2 x double> %2, <2 x double> undef, <4 x i32> zeroinitializer
+  ret <4 x double> %3
+}
+
+define <4 x double> @splat_v4f64(<2 x double> %r) {
+; AVX1-LABEL: splat_v4f64:
+; AVX1:       # BB#0:
+; AVX1-NEXT:    vunpcklpd {{.*#+}} xmm0 = xmm0[0,0]
+; AVX1-NEXT:    vinsertf128 $1, %xmm0, %ymm0, %ymm0
+; AVX1-NEXT:    retq
+;
+; AVX2-LABEL: splat_v4f64:
+; AVX2:       # BB#0:
+; AVX2-NEXT:    vbroadcastsd %xmm0, %ymm0
+; AVX2-NEXT:    retq
+  %1 = shufflevector <2 x double> %r, <2 x double> undef, <4 x i32> zeroinitializer
+  ret <4 x double> %1
+}

Modified: llvm/trunk/test/CodeGen/X86/vector-shuffle-256-v8.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/vector-shuffle-256-v8.ll?rev=219617&r1=219616&r2=219617&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/vector-shuffle-256-v8.ll (original)
+++ llvm/trunk/test/CodeGen/X86/vector-shuffle-256-v8.ll Mon Oct 13 11:16:16 2014
@@ -1579,3 +1579,29 @@ define <8 x i32> @shuffle_v8i32_6caa87e5
   %shuffle = shufflevector <8 x i32> %a, <8 x i32> %b, <8 x i32> <i32 6, i32 12, i32 10, i32 10, i32 8, i32 7, i32 14, i32 5>
   ret <8 x i32> %shuffle
 }
+
+define <8 x float> @splat_mem_v8f32_2(float* %p) {
+; ALL-LABEL: splat_mem_v8f32_2:
+; ALL:       # BB#0:
+; ALL-NEXT:    vbroadcastss (%rdi), %ymm0
+; ALL-NEXT:    retq
+  %1 = load float* %p
+  %2 = insertelement <4 x float> undef, float %1, i32 0
+  %3 = shufflevector <4 x float> %2, <4 x float> undef, <8 x i32> zeroinitializer
+  ret <8 x float> %3
+}
+
+define <8 x float> @splat_v8f32(<4 x float> %r) {
+; AVX1-LABEL: splat_v8f32:
+; AVX1:       # BB#0:
+; AVX1-NEXT:    vpermilps {{.*#+}} xmm0 = xmm0[0,0,0,0]
+; AVX1-NEXT:    vinsertf128 $1, %xmm0, %ymm0, %ymm0
+; AVX1-NEXT:    retq
+;
+; AVX2-LABEL: splat_v8f32:
+; AVX2:       # BB#0:
+; AVX2-NEXT:    vbroadcastss %xmm0, %ymm0
+; AVX2-NEXT:    retq
+  %1 = shufflevector <4 x float> %r, <4 x float> undef, <8 x i32> zeroinitializer
+  ret <8 x float> %1
+}