SDag: fix how initial loads are formed when splitting vector ops.

Later code expects the vector loads produced to be directly
concatenable, which means we shouldn't pad anything except the last load
produced with UNDEF.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293088 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index df7846cb57430578a2e41f1424c229fe1382d064..74740d1641adeb96e477c2d3e6aa4fd6b8f3c3cc 100644 (file)
--- a/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -3442,7 +3442,10 @@ SDValue DAGTypeLegalizer::GenWidenVectorLoads(SmallVectorImpl<SDValue> &LdChain,
                       LD->getPointerInfo().getWithOffset(Offset),
                       MinAlign(Align, Increment), MMOFlags, AAInfo);
       LdChain.push_back(L.getValue(1));
-      if (L->getValueType(0).isVector()) {
+      if (L->getValueType(0).isVector() && NewVTWidth >= LdWidth) {
+        // Later code assumes the vector loads produced will be mergeable, so we
+        // must pad the final entry up to the previous width. Scalars are
+        // combined separately.
         SmallVector<SDValue, 16> Loads;
         Loads.push_back(L);
         unsigned size = L->getValueSizeInBits(0);

diff --git a/test/CodeGen/ARM/vector-load.ll b/test/CodeGen/ARM/vector-load.ll
index a638c2bdb9beddec6ebe3741b7347c591bca6135..ed734723a86d34012e04308fed5e35e26c700548 100644 (file)
--- a/test/CodeGen/ARM/vector-load.ll
+++ b/test/CodeGen/ARM/vector-load.ll
@@ -251,3 +251,13 @@ define <4 x i32> @zextload_v8i8tov8i32_fake_update(<4 x i8>** %ptr) {
         %zlA = zext <4 x i8> %lA to <4 x i32>
        ret <4 x i32> %zlA
 }
+
+; CHECK-LABEL: test_silly_load:
+; CHECK: ldr {{r[0-9]+}}, [r0, #24]
+; CHECK: vld1.8 {d{{[0-9]+}}, d{{[0-9]+}}}, [r0:128]!
+; CHECK: vldr d{{[0-9]+}}, [r0]
+
+define void @test_silly_load(<28 x i8>* %addr) {
+  load volatile <28 x i8>, <28 x i8>* %addr
+  ret void
+}