Add basic support for NEON modified immediates besides VMOV.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106030 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 25 insertions, 13 deletions

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 5fb3856..725d42c 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -2766,10 +2766,18 @@ static SDValue LowerVSETCC(SDValue Op, SelectionDAG &DAG) {
 /// bits7-0=Immediate.
 static SDValue isNEONModifiedImm(uint64_t SplatBits, uint64_t SplatUndef,
                                  unsigned SplatBitSize, SelectionDAG &DAG,
-                                 bool DoEncode) {
+                                 bool isVMOV, bool DoEncode) {
   unsigned Op, Cmode, Imm;
   EVT VT;
 
+  // SplatBitSize is set to the smallest size that splats the vector, so a
+  // zero vector will always have SplatBitSize == 8.  However, NEON modified
+  // immediate instructions others than VMOV do not support the 8-bit encoding
+  // of a zero vector, and the default encoding of zero is supposed to be the
+  // 32-bit version.
+  if (SplatBits == 0)
+    SplatBitSize = 32;
+
   Op = 0;
   switch (SplatBitSize) {
   case 8:
@@ -2855,6 +2863,8 @@ static SDValue isNEONModifiedImm(uint64_t SplatBits, uint64_t SplatUndef,
 
   case 64: {
     // NEON has a 64-bit VMOV splat where each byte is either 0 or 0xff.
+    if (!isVMOV)
+      return SDValue();
     uint64_t BitMask = 0xff;
     uint64_t Val = 0;
     unsigned ImmMask = 1;
@@ -2892,7 +2902,8 @@ static SDValue isNEONModifiedImm(uint64_t SplatBits, uint64_t SplatUndef,
 /// with a "modified immediate" operand (e.g., VMOV) of the specified element
 /// size, return the encoded value for that immediate.  The ByteSize field
 /// indicates the number of bytes of each element [1248].
-SDValue ARM::getNEONModImm(SDNode *N, unsigned ByteSize, SelectionDAG &DAG) {
+SDValue ARM::getNEONModImm(SDNode *N, unsigned ByteSize, bool isVMOV,
+                           SelectionDAG &DAG) {
   BuildVectorSDNode *BVN = dyn_cast<BuildVectorSDNode>(N);
   APInt SplatBits, SplatUndef;
   unsigned SplatBitSize;
@@ -2905,7 +2916,7 @@ SDValue ARM::getNEONModImm(SDNode *N, unsigned ByteSize, SelectionDAG &DAG) {
     return SDValue();
 
   return isNEONModifiedImm(SplatBits.getZExtValue(), SplatUndef.getZExtValue(),
-                           SplatBitSize, DAG, true);
+                           SplatBitSize, DAG, isVMOV, true);
 }
 
 static bool isVEXTMask(const SmallVectorImpl<int> &M, EVT VT,
@@ -3148,7 +3159,7 @@ static SDValue LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) {
       // Check if an immediate VMOV works.
       SDValue Val = isNEONModifiedImm(SplatBits.getZExtValue(),
                                       SplatUndef.getZExtValue(),
-                                      SplatBitSize, DAG, false);
+                                      SplatBitSize, DAG, true, false);
       if (Val.getNode())
         return BuildSplat(Val, VT, DAG, dl);
     }
diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index d9f47d9..787272c 100644
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -154,7 +154,8 @@ namespace llvm {
     /// instruction with a "modified immediate" operand (e.g., VMOV) of the
     /// specified element size, return the encoded value for that immediate.
     /// The ByteSize field indicates the number of bytes of each element [1248].
-    SDValue getNEONModImm(SDNode *N, unsigned ByteSize, SelectionDAG &DAG);
+    SDValue getNEONModImm(SDNode *N, unsigned ByteSize, bool isVMOV,
+                          SelectionDAG &DAG);
 
     /// getVFPf32Imm / getVFPf64Imm - If the given fp immediate can be
     /// materialized with a VMOV.f32 / VMOV.f64 (i.e. fconsts / fconstd)
diff --git a/lib/Target/ARM/ARMInstrNEON.td b/lib/Target/ARM/ARMInstrNEON.td
index 6ae755e..cc2fddd 100644
--- a/lib/Target/ARM/ARMInstrNEON.td
+++ b/lib/Target/ARM/ARMInstrNEON.td
@@ -2820,34 +2820,34 @@ def  VMOVQQQQ : PseudoInst<(outs QQQQPR:$dst), (ins QQQQPR:$src),
 
 // VMOV_get_imm8 xform function: convert build_vector to VMOV.i8 imm.
 def VMOV_get_imm8 : SDNodeXForm<build_vector, [{
-  return ARM::getNEONModImm(N, 1, *CurDAG);
+  return ARM::getNEONModImm(N, 1, true, *CurDAG);
 }]>;
 def vmovImm8 : PatLeaf<(build_vector), [{
-  return ARM::getNEONModImm(N, 1, *CurDAG).getNode() != 0;
+  return ARM::getNEONModImm(N, 1, true, *CurDAG).getNode() != 0;
 }], VMOV_get_imm8>;
 
 // VMOV_get_imm16 xform function: convert build_vector to VMOV.i16 imm.
 def VMOV_get_imm16 : SDNodeXForm<build_vector, [{
-  return ARM::getNEONModImm(N, 2, *CurDAG);
+  return ARM::getNEONModImm(N, 2, true, *CurDAG);
 }]>;
 def vmovImm16 : PatLeaf<(build_vector), [{
-  return ARM::getNEONModImm(N, 2, *CurDAG).getNode() != 0;
+  return ARM::getNEONModImm(N, 2, true, *CurDAG).getNode() != 0;
 }], VMOV_get_imm16>;
 
 // VMOV_get_imm32 xform function: convert build_vector to VMOV.i32 imm.
 def VMOV_get_imm32 : SDNodeXForm<build_vector, [{
-  return ARM::getNEONModImm(N, 4, *CurDAG);
+  return ARM::getNEONModImm(N, 4, true, *CurDAG);
 }]>;
 def vmovImm32 : PatLeaf<(build_vector), [{
-  return ARM::getNEONModImm(N, 4, *CurDAG).getNode() != 0;
+  return ARM::getNEONModImm(N, 4, true, *CurDAG).getNode() != 0;
 }], VMOV_get_imm32>;
 
 // VMOV_get_imm64 xform function: convert build_vector to VMOV.i64 imm.
 def VMOV_get_imm64 : SDNodeXForm<build_vector, [{
-  return ARM::getNEONModImm(N, 8, *CurDAG);
+  return ARM::getNEONModImm(N, 8, true, *CurDAG);
 }]>;
 def vmovImm64 : PatLeaf<(build_vector), [{
-  return ARM::getNEONModImm(N, 8, *CurDAG).getNode() != 0;
+  return ARM::getNEONModImm(N, 8, true, *CurDAG).getNode() != 0;
 }], VMOV_get_imm64>;
 
 // Note: Some of the cmode bits in the following VMOV instructions need to