GlobalISel (AArch64): fix ABI at border between GPRs and SP.

If a struct would end up half in GPRs and half on SP the ABI says it should
actually go entirely on the stack. We were getting this wrong in GlobalISel
before, causing compatibility issues.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311137 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/AArch64/AArch64CallLowering.cpp

@@ -188,12 +188,16 @@ void AArch64CallLowering::splitToValueTypes(
   }
 
   unsigned FirstRegIdx = SplitArgs.size();
+  bool AlreadySplit = false;
   for (auto SplitVT : SplitVTs) {
-    // FIXME: set split flags if they're actually used (e.g. i128 on AAPCS).
     Type *SplitTy = SplitVT.getTypeForEVT(Ctx);
     SplitArgs.push_back(
         ArgInfo{MRI.createGenericVirtualRegister(getLLTForType(*SplitTy, DL)),
                 SplitTy, OrigArg.Flags, OrigArg.IsFixed});
+    if (!AlreadySplit) {
+      SplitArgs.back().Flags.setSplit();
+      AlreadySplit = true;
+    }
   }
 
   for (unsigned i = 0; i < Offsets.size(); ++i)

test/CodeGen/AArch64/GlobalISel/call-translator.ll

@@ -215,3 +215,42 @@ define void @test_call_stack() {
 define void @test_mem_i1([8 x i64], i1 %in) {
   ret void
 }
+
+; CHECK-LABEL: name: test_split_struct
+; CHECK: [[STRUCT:%[0-9]+]](s128) = G_LOAD {{.*}}(p0)
+; CHECK: [[LO:%[0-9]+]](s64) = G_EXTRACT [[STRUCT]](s128), 0
+; CHECK: [[HI:%[0-9]+]](s64) = G_EXTRACT [[STRUCT]](s128), 64
+
+; CHECK: [[SP:%[0-9]+]](p0) = COPY %sp
+; CHECK: [[OFF:%[0-9]+]](s64) = G_CONSTANT i64 0
+; CHECK: [[ADDR:%[0-9]+]](p0) = G_GEP [[SP]], [[OFF]]
+; CHECK: G_STORE [[LO]](s64), [[ADDR]](p0) :: (store 8 into stack, align 0)
+
+; CHECK: [[SP:%[0-9]+]](p0) = COPY %sp
+; CHECK: [[OFF:%[0-9]+]](s64) = G_CONSTANT i64 8
+; CHECK: [[ADDR:%[0-9]+]](p0) = G_GEP [[SP]], [[OFF]]
+; CHECK: G_STORE [[HI]](s64), [[ADDR]](p0) :: (store 8 into stack + 8, align 0)
+define void @test_split_struct([2 x i64]* %ptr) {
+  %struct = load [2 x i64], [2 x i64]* %ptr
+  call void @take_split_struct([2 x i64]* null, i64 1, i64 2, i64 3,
+                               i64 4, i64 5, i64 6,
+                               [2 x i64] %struct)
+  ret void
+}
+
+; CHECK-LABEL: name: take_split_struct
+; CHECK: fixedStack:
+; CHECK-DAG:   - { id: [[LO_FRAME:[0-9]+]], type: default, offset: 0, size: 8
+; CHECK-DAG:   - { id: [[HI_FRAME:[0-9]+]], type: default, offset: 8, size: 8
+
+; CHECK: [[LOPTR:%[0-9]+]](p0) = G_FRAME_INDEX %fixed-stack.[[LO_FRAME]]
+; CHECK: [[LO:%[0-9]+]](s64) = G_LOAD [[LOPTR]](p0) :: (invariant load 8 from %fixed-stack.[[LO_FRAME]], align 0)
+
+; CHECK: [[HIPTR:%[0-9]+]](p0) = G_FRAME_INDEX %fixed-stack.[[HI_FRAME]]
+; CHECK: [[HI:%[0-9]+]](s64) = G_LOAD [[HIPTR]](p0) :: (invariant load 8 from %fixed-stack.[[HI_FRAME]], align 0)
+define void @take_split_struct([2 x i64]* %ptr, i64, i64, i64,
+                               i64, i64, i64,
+                               [2 x i64] %in) {
+  store [2 x i64] %in, [2 x i64]* %ptr
+  ret void
+}