[llvm] r213915 - [PATCH][PPC64LE] Correct little-endian usage of vmrgh* and vmrgl*.

Bill Schmidt wschmidt at linux.vnet.ibm.com
Thu Jul 24 18:55:55 PDT 2014


Author: wschmidt
Date: Thu Jul 24 20:55:55 2014
New Revision: 213915

URL: http://llvm.org/viewvc/llvm-project?rev=213915&view=rev
Log:
[PATCH][PPC64LE] Correct little-endian usage of vmrgh* and vmrgl*.

Because the PowerPC vmrgh* and vmrgl* instructions have a built-in
big-endian bias, it is necessary to swap their inputs in little-endian
mode when using them to implement a vector shuffle.  This was
previously missed in the vector LE implementation.

There was already logic to distinguish between unary and "normal"
vmrg* vector shuffles, so this patch extends that logic to use a third
option:  "swapped" vmrg* vector shuffles that are used for little
endian in place of the "normal" ones.

I've updated the vec-shuffle-le.ll test to check for the expected
register ordering on the generated instructions.

This bug was discovered when testing the LE and ELFv2 patches for
safety if they were backported to 3.4.  A different vectorization
decision was made in 3.4 than on mainline trunk, and that exposed the
problem.  I've verified this fix takes care of that issue.


Modified:
    llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp
    llvm/trunk/lib/Target/PowerPC/PPCISelLowering.h
    llvm/trunk/lib/Target/PowerPC/PPCInstrAltivec.td
    llvm/trunk/test/CodeGen/PowerPC/vec_shuffle_le.ll

Modified: llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp?rev=213915&r1=213914&r2=213915&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp Thu Jul 24 20:55:55 2014
@@ -926,31 +926,51 @@ static bool isVMerge(ShuffleVectorSDNode
 
 /// isVMRGLShuffleMask - Return true if this is a shuffle mask suitable for
 /// a VMRGL* instruction with the specified unit size (1,2 or 4 bytes).
+/// The ShuffleKind distinguishes between big-endian merges with two 
+/// different inputs (0), either-endian merges with two identical inputs (1),
+/// and little-endian merges with two different inputs (2).  For the latter,
+/// the input operands are swapped (see PPCInstrAltivec.td).
 bool PPC::isVMRGLShuffleMask(ShuffleVectorSDNode *N, unsigned UnitSize,
-                             bool isUnary, SelectionDAG &DAG) {
+                             unsigned ShuffleKind, SelectionDAG &DAG) {
   if (DAG.getTarget().getDataLayout()->isLittleEndian()) {
-    if (!isUnary)
+    if (ShuffleKind == 1) // unary
+      return isVMerge(N, UnitSize, 0, 0);
+    else if (ShuffleKind == 2) // swapped
       return isVMerge(N, UnitSize, 0, 16);
-    return isVMerge(N, UnitSize, 0, 0);
+    else
+      return false;
   } else {
-    if (!isUnary)
+    if (ShuffleKind == 1) // unary
+      return isVMerge(N, UnitSize, 8, 8);
+    else if (ShuffleKind == 0) // normal
       return isVMerge(N, UnitSize, 8, 24);
-    return isVMerge(N, UnitSize, 8, 8);
+    else
+      return false;
   }
 }
 
 /// isVMRGHShuffleMask - Return true if this is a shuffle mask suitable for
 /// a VMRGH* instruction with the specified unit size (1,2 or 4 bytes).
+/// The ShuffleKind distinguishes between big-endian merges with two 
+/// different inputs (0), either-endian merges with two identical inputs (1),
+/// and little-endian merges with two different inputs (2).  For the latter,
+/// the input operands are swapped (see PPCInstrAltivec.td).
 bool PPC::isVMRGHShuffleMask(ShuffleVectorSDNode *N, unsigned UnitSize,
-                             bool isUnary, SelectionDAG &DAG) {
+                             unsigned ShuffleKind, SelectionDAG &DAG) {
   if (DAG.getTarget().getDataLayout()->isLittleEndian()) {
-    if (!isUnary)
+    if (ShuffleKind == 1) // unary
+      return isVMerge(N, UnitSize, 8, 8);
+    else if (ShuffleKind == 2) // swapped
       return isVMerge(N, UnitSize, 8, 24);
-    return isVMerge(N, UnitSize, 8, 8);
+    else
+      return false;
   } else {
-    if (!isUnary)
+    if (ShuffleKind == 1) // unary
+      return isVMerge(N, UnitSize, 0, 0);
+    else if (ShuffleKind == 0) // normal
       return isVMerge(N, UnitSize, 0, 16);
-    return isVMerge(N, UnitSize, 0, 0);
+    else
+      return false;
   }
 }
 
@@ -6021,12 +6041,12 @@ SDValue PPCTargetLowering::LowerVECTOR_S
         PPC::isVPKUWUMShuffleMask(SVOp, true, DAG) ||
         PPC::isVPKUHUMShuffleMask(SVOp, true, DAG) ||
         PPC::isVSLDOIShuffleMask(SVOp, true, DAG) != -1 ||
-        PPC::isVMRGLShuffleMask(SVOp, 1, true, DAG) ||
-        PPC::isVMRGLShuffleMask(SVOp, 2, true, DAG) ||
-        PPC::isVMRGLShuffleMask(SVOp, 4, true, DAG) ||
-        PPC::isVMRGHShuffleMask(SVOp, 1, true, DAG) ||
-        PPC::isVMRGHShuffleMask(SVOp, 2, true, DAG) ||
-        PPC::isVMRGHShuffleMask(SVOp, 4, true, DAG)) {
+        PPC::isVMRGLShuffleMask(SVOp, 1, 1, DAG) ||
+        PPC::isVMRGLShuffleMask(SVOp, 2, 1, DAG) ||
+        PPC::isVMRGLShuffleMask(SVOp, 4, 1, DAG) ||
+        PPC::isVMRGHShuffleMask(SVOp, 1, 1, DAG) ||
+        PPC::isVMRGHShuffleMask(SVOp, 2, 1, DAG) ||
+        PPC::isVMRGHShuffleMask(SVOp, 4, 1, DAG)) {
       return Op;
     }
   }
@@ -6034,15 +6054,16 @@ SDValue PPCTargetLowering::LowerVECTOR_S
   // Altivec has a variety of "shuffle immediates" that take two vector inputs
   // and produce a fixed permutation.  If any of these match, do not lower to
   // VPERM.
+  unsigned int ShuffleKind = isLittleEndian ? 2 : 0;
   if (PPC::isVPKUWUMShuffleMask(SVOp, false, DAG) ||
       PPC::isVPKUHUMShuffleMask(SVOp, false, DAG) ||
       PPC::isVSLDOIShuffleMask(SVOp, false, DAG) != -1 ||
-      PPC::isVMRGLShuffleMask(SVOp, 1, false, DAG) ||
-      PPC::isVMRGLShuffleMask(SVOp, 2, false, DAG) ||
-      PPC::isVMRGLShuffleMask(SVOp, 4, false, DAG) ||
-      PPC::isVMRGHShuffleMask(SVOp, 1, false, DAG) ||
-      PPC::isVMRGHShuffleMask(SVOp, 2, false, DAG) ||
-      PPC::isVMRGHShuffleMask(SVOp, 4, false, DAG))
+      PPC::isVMRGLShuffleMask(SVOp, 1, ShuffleKind, DAG) ||
+      PPC::isVMRGLShuffleMask(SVOp, 2, ShuffleKind, DAG) ||
+      PPC::isVMRGLShuffleMask(SVOp, 4, ShuffleKind, DAG) ||
+      PPC::isVMRGHShuffleMask(SVOp, 1, ShuffleKind, DAG) ||
+      PPC::isVMRGHShuffleMask(SVOp, 2, ShuffleKind, DAG) ||
+      PPC::isVMRGHShuffleMask(SVOp, 4, ShuffleKind, DAG))
     return Op;
 
   // Check to see if this is a shuffle of 4-byte values.  If so, we can use our

Modified: llvm/trunk/lib/Target/PowerPC/PPCISelLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCISelLowering.h?rev=213915&r1=213914&r2=213915&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCISelLowering.h (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCISelLowering.h Thu Jul 24 20:55:55 2014
@@ -308,12 +308,12 @@ namespace llvm {
     /// isVMRGLShuffleMask - Return true if this is a shuffle mask suitable for
     /// a VRGL* instruction with the specified unit size (1,2 or 4 bytes).
     bool isVMRGLShuffleMask(ShuffleVectorSDNode *N, unsigned UnitSize,
-                            bool isUnary, SelectionDAG &DAG);
+                            unsigned ShuffleKind, SelectionDAG &DAG);
 
     /// isVMRGHShuffleMask - Return true if this is a shuffle mask suitable for
     /// a VRGH* instruction with the specified unit size (1,2 or 4 bytes).
     bool isVMRGHShuffleMask(ShuffleVectorSDNode *N, unsigned UnitSize,
-                            bool isUnary, SelectionDAG &DAG);
+                            unsigned ShuffleKind, SelectionDAG &DAG);
 
     /// isVSLDOIShuffleMask - If this is a vsldoi shuffle mask, return the shift
     /// amount, otherwise return -1.

Modified: llvm/trunk/lib/Target/PowerPC/PPCInstrAltivec.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCInstrAltivec.td?rev=213915&r1=213914&r2=213915&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCInstrAltivec.td (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCInstrAltivec.td Thu Jul 24 20:55:55 2014
@@ -44,65 +44,81 @@ def vpkuwum_unary_shuffle : PatFrag<(ops
 
 def vmrglb_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                              (vector_shuffle (v16i8 node:$lhs), node:$rhs), [{
-  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 1, false,
-                                 *CurDAG);
+  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 1, 0, *CurDAG);
 }]>;
 def vmrglh_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                              (vector_shuffle (v16i8 node:$lhs), node:$rhs), [{
-  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 2, false,
-                                 *CurDAG);
+  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 2, 0, *CurDAG);
 }]>;
 def vmrglw_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                              (vector_shuffle (v16i8 node:$lhs), node:$rhs), [{
-  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 4, false,
-                                 *CurDAG);
+  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 4, 0, *CurDAG);
 }]>;
 def vmrghb_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                              (vector_shuffle (v16i8 node:$lhs), node:$rhs), [{
-  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 1, false,
-                                 *CurDAG);
+  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 1, 0, *CurDAG);
 }]>;
 def vmrghh_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                              (vector_shuffle (v16i8 node:$lhs), node:$rhs), [{
-  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 2, false,
-                                 *CurDAG);
+  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 2, 0, *CurDAG);
 }]>;
 def vmrghw_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                              (vector_shuffle (v16i8 node:$lhs), node:$rhs), [{
-  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 4, false,
-                                 *CurDAG);
+  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 4, 0, *CurDAG);
 }]>;
 
 
 def vmrglb_unary_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                                (vector_shuffle (v16i8 node:$lhs), node:$rhs), [{
-  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 1, true,
-                                 *CurDAG);
+  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 1, 1, *CurDAG);
 }]>;
 def vmrglh_unary_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                                    (vector_shuffle node:$lhs, node:$rhs), [{
-  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 2, true,
-                                 *CurDAG);
+  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 2, 1, *CurDAG);
 }]>;
 def vmrglw_unary_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                                    (vector_shuffle node:$lhs, node:$rhs), [{
-  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 4, true,
-                                 *CurDAG);
+  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 4, 1, *CurDAG);
 }]>;
 def vmrghb_unary_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                                    (vector_shuffle node:$lhs, node:$rhs), [{
-  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 1, true,
-                                 *CurDAG);
+  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 1, 1, *CurDAG);
 }]>;
 def vmrghh_unary_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                                    (vector_shuffle node:$lhs, node:$rhs), [{
-  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 2, true,
-                                 *CurDAG);
+  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 2, 1, *CurDAG);
 }]>;
 def vmrghw_unary_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
                                    (vector_shuffle node:$lhs, node:$rhs), [{
-  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 4, true,
-                                 *CurDAG);
+  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 4, 1, *CurDAG);
+}]>;
+
+
+// These fragments are provided for little-endian, where the inputs must be
+// swapped for correct semantics.
+def vmrglb_swapped_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
+                               (vector_shuffle (v16i8 node:$lhs), node:$rhs), [{
+  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 1, 2, *CurDAG);
+}]>;
+def vmrglh_swapped_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
+                                   (vector_shuffle node:$lhs, node:$rhs), [{
+  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 2, 2, *CurDAG);
+}]>;
+def vmrglw_swapped_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
+                                   (vector_shuffle node:$lhs, node:$rhs), [{
+  return PPC::isVMRGLShuffleMask(cast<ShuffleVectorSDNode>(N), 4, 2, *CurDAG);
+}]>;
+def vmrghb_swapped_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
+                                   (vector_shuffle node:$lhs, node:$rhs), [{
+  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 1, 2, *CurDAG);
+}]>;
+def vmrghh_swapped_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
+                                   (vector_shuffle node:$lhs, node:$rhs), [{
+  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 2, 2, *CurDAG);
+}]>;
+def vmrghw_swapped_shuffle : PatFrag<(ops node:$lhs, node:$rhs),
+                                   (vector_shuffle node:$lhs, node:$rhs), [{
+  return PPC::isVMRGHShuffleMask(cast<ShuffleVectorSDNode>(N), 4, 2, *CurDAG);
 }]>;
 
 
@@ -803,6 +819,22 @@ def:Pat<(vmrghh_unary_shuffle v16i8:$vA,
 def:Pat<(vmrghw_unary_shuffle v16i8:$vA, undef),
         (VMRGHW $vA, $vA)>;
 
+// Match vmrg*(y,x), i.e., swapped operands.  These fragments
+// are matched for little-endian, where the inputs must be
+// swapped for correct semantics.
+def:Pat<(vmrglb_swapped_shuffle v16i8:$vA, v16i8:$vB),
+        (VMRGLB $vB, $vA)>;
+def:Pat<(vmrglh_swapped_shuffle v16i8:$vA, v16i8:$vB),
+        (VMRGLH $vB, $vA)>;
+def:Pat<(vmrglw_swapped_shuffle v16i8:$vA, v16i8:$vB),
+        (VMRGLW $vB, $vA)>;
+def:Pat<(vmrghb_swapped_shuffle v16i8:$vA, v16i8:$vB),
+        (VMRGHB $vB, $vA)>;
+def:Pat<(vmrghh_swapped_shuffle v16i8:$vA, v16i8:$vB),
+        (VMRGHH $vB, $vA)>;
+def:Pat<(vmrghw_swapped_shuffle v16i8:$vA, v16i8:$vB),
+        (VMRGHW $vB, $vA)>;
+
 // Logical Operations
 def : Pat<(vnot_ppc v4i32:$vA), (VNOR $vA, $vA)>;
 

Modified: llvm/trunk/test/CodeGen/PowerPC/vec_shuffle_le.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/vec_shuffle_le.ll?rev=213915&r1=213914&r2=213915&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/PowerPC/vec_shuffle_le.ll (original)
+++ llvm/trunk/test/CodeGen/PowerPC/vec_shuffle_le.ll Thu Jul 24 20:55:55 2014
@@ -48,7 +48,9 @@ entry:
         %tmp = load <16 x i8>* %A
         %tmp2 = load <16 x i8>* %B
         %tmp3 = shufflevector <16 x i8> %tmp, <16 x i8> %tmp2, <16 x i32> <i32 0, i32 16, i32 1, i32 17, i32 2, i32 18, i32 3, i32 19, i32 4, i32 20, i32 5, i32 21, i32 6, i32 22, i32 7, i32 23>
-; CHECK: vmrglb
+; CHECK: lvx [[REG1:[0-9]+]]
+; CHECK: lvx [[REG2:[0-9]+]]
+; CHECK: vmrglb [[REG3:[0-9]+]], [[REG2]], [[REG1]]
         store <16 x i8> %tmp3, <16 x i8>* %A
         ret void
 }
@@ -69,7 +71,9 @@ entry:
         %tmp = load <16 x i8>* %A
         %tmp2 = load <16 x i8>* %B
         %tmp3 = shufflevector <16 x i8> %tmp, <16 x i8> %tmp2, <16 x i32> <i32 8, i32 24, i32 9, i32 25, i32 10, i32 26, i32 11, i32 27, i32 12, i32 28, i32 13, i32 29, i32 14, i32 30, i32 15, i32 31>
-; CHECK: vmrghb
+; CHECK: lvx [[REG1:[0-9]+]]
+; CHECK: lvx [[REG2:[0-9]+]]
+; CHECK: vmrghb [[REG3:[0-9]+]], [[REG2]], [[REG1]]
         store <16 x i8> %tmp3, <16 x i8>* %A
         ret void
 }
@@ -90,7 +94,9 @@ entry:
         %tmp = load <16 x i8>* %A
         %tmp2 = load <16 x i8>* %B
         %tmp3 = shufflevector <16 x i8> %tmp, <16 x i8> %tmp2, <16 x i32> <i32 0, i32 1, i32 16, i32 17, i32 2, i32 3, i32 18, i32 19, i32 4, i32 5, i32 20, i32 21, i32 6, i32 7, i32 22, i32 23>
-; CHECK: vmrglh
+; CHECK: lvx [[REG1:[0-9]+]]
+; CHECK: lvx [[REG2:[0-9]+]]
+; CHECK: vmrglh [[REG3:[0-9]+]], [[REG2]], [[REG1]]
         store <16 x i8> %tmp3, <16 x i8>* %A
         ret void
 }
@@ -111,7 +117,9 @@ entry:
         %tmp = load <16 x i8>* %A
         %tmp2 = load <16 x i8>* %B
         %tmp3 = shufflevector <16 x i8> %tmp, <16 x i8> %tmp2, <16 x i32> <i32 8, i32 9, i32 24, i32 25, i32 10, i32 11, i32 26, i32 27, i32 12, i32 13, i32 28, i32 29, i32 14, i32 15, i32 30, i32 31>
-; CHECK: vmrghh
+; CHECK: lvx [[REG1:[0-9]+]]
+; CHECK: lvx [[REG2:[0-9]+]]
+; CHECK: vmrghh [[REG3:[0-9]+]], [[REG2]], [[REG1]]
         store <16 x i8> %tmp3, <16 x i8>* %A
         ret void
 }
@@ -132,7 +140,9 @@ entry:
         %tmp = load <16 x i8>* %A
         %tmp2 = load <16 x i8>* %B
         %tmp3 = shufflevector <16 x i8> %tmp, <16 x i8> %tmp2, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 16, i32 17, i32 18, i32 19, i32 4, i32 5, i32 6, i32 7, i32 20, i32 21, i32 22, i32 23>
-; CHECK: vmrglw
+; CHECK: lvx [[REG1:[0-9]+]]
+; CHECK: lvx [[REG2:[0-9]+]]
+; CHECK: vmrglw [[REG3:[0-9]+]], [[REG2]], [[REG1]]
         store <16 x i8> %tmp3, <16 x i8>* %A
         ret void
 }
@@ -153,7 +163,9 @@ entry:
         %tmp = load <16 x i8>* %A
         %tmp2 = load <16 x i8>* %B
         %tmp3 = shufflevector <16 x i8> %tmp, <16 x i8> %tmp2, <16 x i32> <i32 8, i32 9, i32 10, i32 11, i32 24, i32 25, i32 26, i32 27, i32 12, i32 13, i32 14, i32 15, i32 28, i32 29, i32 30, i32 31>
-; CHECK: vmrghw
+; CHECK: lvx [[REG1:[0-9]+]]
+; CHECK: lvx [[REG2:[0-9]+]]
+; CHECK: vmrghw [[REG3:[0-9]+]], [[REG2]], [[REG1]]
         store <16 x i8> %tmp3, <16 x i8>* %A
         ret void
 }





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