From 435e38a5df057385d2e2d6471c330af1bf43306b Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@intel.com>
Date: Fri, 12 Oct 2018 21:59:55 +0000
Subject: [PATCH] [LegalizeVectorTypes] When widening the result of a bitcast
 from a scalar type, use a scalar_to_vector to turn the scalar into a vector
 intead of a build vector full of mostly undefs.

This is more consistent with what we usually do and matches some code X86 custom emits in some cases that I think I can cleanup.

The MIPS test change just looks to be an instruction ordering change.

llvm-svn: 344422
---
 .../CodeGen/SelectionDAG/LegalizeVectorTypes.cpp   | 26 ++++++++++------------
 llvm/test/CodeGen/Mips/cconv/vector.ll             | 24 ++++++++++----------
 2 files changed, 24 insertions(+), 26 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index 310f5ef..f4cad79 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -3022,22 +3022,20 @@ SDValue DAGTypeLegalizer::WidenVecRes_BITCAST(SDNode *N) {
     }
 
     if (TLI.isTypeLegal(NewInVT)) {
-      // Because the result and the input are different vector types, widening
-      // the result could create a legal type but widening the input might make
-      // it an illegal type that might lead to repeatedly splitting the input
-      // and then widening it. To avoid this, we widen the input only if
-      // it results in a legal type.
-      SmallVector<SDValue, 16> Ops(NewNumElts);
-      SDValue UndefVal = DAG.getUNDEF(InVT);
-      Ops[0] = InOp;
-      for (unsigned i = 1; i < NewNumElts; ++i)
-        Ops[i] = UndefVal;
-
       SDValue NewVec;
-      if (InVT.isVector())
+      if (InVT.isVector()) {
+        // Because the result and the input are different vector types, widening
+        // the result could create a legal type but widening the input might make
+        // it an illegal type that might lead to repeatedly splitting the input
+        // and then widening it. To avoid this, we widen the input only if
+        // it results in a legal type.
+        SmallVector<SDValue, 16> Ops(NewNumElts, DAG.getUNDEF(InVT));
+        Ops[0] = InOp;
+
         NewVec = DAG.getNode(ISD::CONCAT_VECTORS, dl, NewInVT, Ops);
-      else
-        NewVec = DAG.getBuildVector(NewInVT, dl, Ops);
+      } else {
+        NewVec = DAG.getNode(ISD::SCALAR_TO_VECTOR, dl, NewInVT, InOp);
+      }
       return DAG.getNode(ISD::BITCAST, dl, WidenVT, NewVec);
     }
   }
diff --git a/llvm/test/CodeGen/Mips/cconv/vector.ll b/llvm/test/CodeGen/Mips/cconv/vector.ll
index 29ffe23..d6e2607 100644
--- a/llvm/test/CodeGen/Mips/cconv/vector.ll
+++ b/llvm/test/CodeGen/Mips/cconv/vector.ll
@@ -2420,10 +2420,10 @@ define void @float_2(<2 x float> %a, <2 x float> %b) {
 ; MIPS64R5EB-NEXT:    lui $1, %hi(%neg(%gp_rel(float_2)))
 ; MIPS64R5EB-NEXT:    daddu $1, $1, $25
 ; MIPS64R5EB-NEXT:    daddiu $1, $1, %lo(%neg(%gp_rel(float_2)))
-; MIPS64R5EB-NEXT:    sd $5, 0($sp)
-; MIPS64R5EB-NEXT:    sd $4, 16($sp)
-; MIPS64R5EB-NEXT:    ld.w $w0, 0($sp)
-; MIPS64R5EB-NEXT:    ld.w $w1, 16($sp)
+; MIPS64R5EB-NEXT:    sd $5, 16($sp)
+; MIPS64R5EB-NEXT:    sd $4, 0($sp)
+; MIPS64R5EB-NEXT:    ld.w $w0, 16($sp)
+; MIPS64R5EB-NEXT:    ld.w $w1, 0($sp)
 ; MIPS64R5EB-NEXT:    fadd.w $w0, $w1, $w0
 ; MIPS64R5EB-NEXT:    shf.w $w0, $w0, 177
 ; MIPS64R5EB-NEXT:    copy_s.d $2, $w0[0]
@@ -2463,10 +2463,10 @@ define void @float_2(<2 x float> %a, <2 x float> %b) {
 ; MIPS64R5EL-NEXT:    lui $1, %hi(%neg(%gp_rel(float_2)))
 ; MIPS64R5EL-NEXT:    daddu $1, $1, $25
 ; MIPS64R5EL-NEXT:    daddiu $1, $1, %lo(%neg(%gp_rel(float_2)))
-; MIPS64R5EL-NEXT:    sd $5, 0($sp)
-; MIPS64R5EL-NEXT:    sd $4, 16($sp)
-; MIPS64R5EL-NEXT:    ld.w $w0, 0($sp)
-; MIPS64R5EL-NEXT:    ld.w $w1, 16($sp)
+; MIPS64R5EL-NEXT:    sd $5, 16($sp)
+; MIPS64R5EL-NEXT:    sd $4, 0($sp)
+; MIPS64R5EL-NEXT:    ld.w $w0, 16($sp)
+; MIPS64R5EL-NEXT:    ld.w $w1, 0($sp)
 ; MIPS64R5EL-NEXT:    fadd.w $w0, $w1, $w0
 ; MIPS64R5EL-NEXT:    copy_s.d $2, $w0[0]
 ; MIPS64R5EL-NEXT:    ld $1, %got_disp(float_res_v2f32)($1)
@@ -6211,14 +6211,14 @@ define float @mixed_i8(<2 x float> %a, i8 %b, <2 x float> %c) {
 ; MIPS64R5-NEXT:    andi $1, $1, 255
 ; MIPS64R5-NEXT:    sw $1, 36($sp)
 ; MIPS64R5-NEXT:    sw $1, 32($sp)
-; MIPS64R5-NEXT:    sd $4, 16($sp)
+; MIPS64R5-NEXT:    sd $4, 0($sp)
 ; MIPS64R5-NEXT:    ld.w $w0, 32($sp)
 ; MIPS64R5-NEXT:    ffint_s.w $w0, $w0
-; MIPS64R5-NEXT:    ld.w $w1, 16($sp)
-; MIPS64R5-NEXT:    fadd.w $w0, $w0, $w1
-; MIPS64R5-NEXT:    sd $6, 0($sp)
 ; MIPS64R5-NEXT:    ld.w $w1, 0($sp)
 ; MIPS64R5-NEXT:    fadd.w $w0, $w0, $w1
+; MIPS64R5-NEXT:    sd $6, 16($sp)
+; MIPS64R5-NEXT:    ld.w $w1, 16($sp)
+; MIPS64R5-NEXT:    fadd.w $w0, $w0, $w1
 ; MIPS64R5-NEXT:    splati.w $w1, $w0[1]
 ; MIPS64R5-NEXT:    add.s $f0, $f0, $f1
 ; MIPS64R5-NEXT:    daddiu $sp, $sp, 48
-- 
2.7.4