[Hexagon] Specify vector alignment in DataLayout string

The DataLayout can calculate alignment of vectors based on the alignment
of the element type and the number of elements. In fact, it is the product
of these two values. The problem is that for vectors of N x i1, this will
return the alignment of N bytes, since the alignment of i1 is 8 bits. The
vector types of vNi1 should be aligned to N bits instead. Provide explicit
alignment for HVX vectors to avoid such complications.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@260678 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Krzysztof Parzyszek

lib/Target/Hexagon/HexagonTargetMachine.cpp

@@ -121,19 +121,19 @@ namespace llvm {
   FunctionPass *createHexagonStoreWidening();
 } // end namespace llvm;
 
-/// HexagonTargetMachine ctor - Create an ILP32 architecture model.
-///
 
-/// Hexagon_TODO: Do I need an aggregate alignment?
-///
 HexagonTargetMachine::HexagonTargetMachine(const Target &T, const Triple &TT,
                                            StringRef CPU, StringRef FS,
                                            const TargetOptions &Options,
                                            Reloc::Model RM, CodeModel::Model CM,
                                            CodeGenOpt::Level OL)
-    : LLVMTargetMachine(T, "e-m:e-p:32:32:32-i64:64:64-i32:32:32-i16:16:16-"
-                        "i1:8:8-f64:64:64-f32:32:32-v64:64:64-v32:32:32-a:0-"
-                        "n16:32", TT, CPU, FS, Options, RM, CM, OL),
+    // Specify the vector alignment explicitly. For v512x1, the calculated
+    // alignment would be 512*alignment(i1), which is 512 bytes, instead of
+    // the required minimum of 64 bytes.
+    : LLVMTargetMachine(T, "e-m:e-p:32:32:32-a:0-n16:32-"
+         "i64:64:64-i32:32:32-i16:16:16-i1:8:8-f32:32:32-f64:64:64-"
+         "v32:32:32-v64:64:64-v512:512:512-v1024:1024:1024-v2048:2048:2048",
+         TT, CPU, FS, Options, RM, CM, OL),
       TLOF(make_unique<HexagonTargetObjectFile>()) {
   initAsmInfo();
 }

test/CodeGen/Hexagon/vector-align.ll

@@ -0,0 +1,38 @@
+; RUN: llc -march=hexagon -mcpu=hexagonv60 -enable-hexagon-hvx < %s \
+; RUN:    | FileCheck %s
+
+; Check that the store to Q6VecPredResult does not get expanded into multiple
+; stores. There should be no memd's. This relies on the alignment specified
+; in the data layout string, so don't provide one here to make sure that the
+; default one from HexagonTargetMachine is correct.
+
+; CHECK-NOT: memd
+
+
+@Q6VecPredResult = common global <16 x i32> zeroinitializer, align 64
+
+; Function Attrs: nounwind
+define i32 @foo() #0 {
+entry:
+  %0 = tail call <16 x i32> @llvm.hexagon.V6.lvsplatw(i32 1)
+  %1 = tail call <512 x i1> @llvm.hexagon.V6.vandvrt(<16 x i32> %0, i32 -2147483648)
+  store <512 x i1> %1, <512 x i1>* bitcast (<16 x i32>* @Q6VecPredResult to <512 x i1>*), align 64, !tbaa !1
+  tail call void @print_vecpred(i32 64, i8* bitcast (<16 x i32>* @Q6VecPredResult to i8*)) #3
+  ret i32 0
+}
+
+; Function Attrs: nounwind readnone
+declare <512 x i1> @llvm.hexagon.V6.vandvrt(<16 x i32>, i32) #1
+
+; Function Attrs: nounwind readnone
+declare <16 x i32> @llvm.hexagon.V6.lvsplatw(i32) #1
+
+declare void @print_vecpred(i32, i8*) #2
+
+attributes #0 = { nounwind "target-cpu"="hexagonv60" "target-features"="+hvx" }
+attributes #1 = { nounwind readnone }
+attributes #2 = { nounwind }
+
+!1 = !{!2, !2, i64 0}
+!2 = !{!"omnipotent char", !3, i64 0}
+!3 = !{!"Simple C/C++ TBAA"}