[PATCH] [PATCH][AArch64]Pattern match failures for truncate store and extend load

[Hao Liu]

Hi t.p.northover,

Hi Tim and reviewers,

In DAG selection, a load and a sext/zext may be combined into a ExtLoad node, and a trunc and a store may be combined into a TruncStore node. But there is no such instructions can directly match ExtLoad and TruncStore. As a result, pattern match will fail.

This patch fixes such problem by setting ExtLoad and TruncStore to be expanded in ISelLowering. So that pattern match will not fail.
Review. Please.

Thanks,
-Hao 

http://llvm-reviews.chandlerc.com/D2350

Files:
  lib/Target/AArch64/AArch64ISelLowering.cpp
  test/CodeGen/AArch64/neon-truncStore-extLoad.ll

Index: lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- lib/Target/AArch64/AArch64ISelLowering.cpp
+++ lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -368,6 +368,25 @@
     setOperationAction(ISD::FROUND, MVT::v4f32, Legal);
     setOperationAction(ISD::FROUND, MVT::v1f64, Legal);
     setOperationAction(ISD::FROUND, MVT::v2f64, Legal);
+
+    // Vector ExtLoad and TruncStore are expanded.
+    for (unsigned I = MVT::FIRST_VECTOR_VALUETYPE;
+         I <= MVT::LAST_VECTOR_VALUETYPE; ++I) {
+      MVT VT = (MVT::SimpleValueType) I;
+      setLoadExtAction(ISD::SEXTLOAD, VT, Expand);
+      setLoadExtAction(ISD::ZEXTLOAD, VT, Expand);
+      setLoadExtAction(ISD::EXTLOAD, VT, Expand);
+      for (unsigned II = MVT::FIRST_VECTOR_VALUETYPE;
+           II <= MVT::LAST_VECTOR_VALUETYPE; ++II) {
+        MVT VT1 = (MVT::SimpleValueType) II;
+        // A TruncStore has two vector types of the same number of elements
+        // and different element sizes.
+        if (VT.getVectorNumElements() == VT1.getVectorNumElements() &&
+            VT.getVectorElementType().getSizeInBits()
+                > VT1.getVectorElementType().getSizeInBits())
+          setTruncStoreAction(VT, VT1, Expand);
+      }
+    }
   }
 }
 
Index: test/CodeGen/AArch64/neon-truncStore-extLoad.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/neon-truncStore-extLoad.ll
@@ -0,0 +1,57 @@
+; RUN: llc < %s -verify-machineinstrs -mtriple=aarch64-none-linux-gnu -mattr=+neon | FileCheck %s
+
+; A vector TruncStore can not be selected.
+; Test a trunc IR and a vector store IR can be selected correctly.
+define void @truncStore.v2i64(<2 x i64> %a, <2 x i32>* %result) {
+; CHECK-LABEL: truncStore.v2i64:
+; CHECK: xtn v{{[0-9]+}}.2s, v{{[0-9]+}}.2d
+; CHECK: st1 {v{{[0-9]+}}.2s}, [x{{[0-9]+|sp}}]
+  %b = trunc <2 x i64> %a to <2 x i32>
+  store <2 x i32> %b, <2 x i32>* %result
+  ret void
+}
+
+define void @truncStore.v4i32(<4 x i32> %a, <4 x i16>* %result) {
+; CHECK-LABEL: truncStore.v4i32:
+; CHECK: xtn v{{[0-9]+}}.4h, v{{[0-9]+}}.4s
+; CHECK: st1 {v{{[0-9]+}}.4h}, [x{{[0-9]+|sp}}]
+  %b = trunc <4 x i32> %a to <4 x i16>
+  store <4 x i16> %b, <4 x i16>* %result
+  ret void
+}
+
+define void @truncStore.v8i16(<8 x i16> %a, <8 x i8>* %result) {
+; CHECK-LABEL: truncStore.v8i16:
+; CHECK: xtn v{{[0-9]+}}.8b, v{{[0-9]+}}.8h
+; CHECK: st1 {v{{[0-9]+}}.8b}, [x{{[0-9]+|sp}}]
+  %b = trunc <8 x i16> %a to <8 x i8>
+  store <8 x i8> %b, <8 x i8>* %result
+  ret void
+}
+
+; A vector LoadExt can not be selected.
+; Test a vector load IR and a sext/zext IR can be selected correctly.
+define <4 x i32> @loadSExt.v4i8(<4 x i8>* %ref) {
+; CHECK-LABEL: loadSExt.v4i8:
+; CHECK: ldrsb
+  %a = load <4 x i8>* %ref
+  %conv = sext <4 x i8> %a to <4 x i32>
+  ret <4 x i32> %conv
+}
+
+define <4 x i32> @loadZExt.v4i8(<4 x i8>* %ref) {
+; CHECK-LABEL: loadZExt.v4i8:
+; CHECK: ldrb
+  %a = load <4 x i8>* %ref
+  %conv = zext <4 x i8> %a to <4 x i32>
+  ret <4 x i32> %conv
+}
+
+define i32 @loadExt.i32(<4 x i8>* %ref) {
+; CHECK-LABEL: loadExt.i32:
+; CHECK: ldrb
+  %a = load <4 x i8>* %ref
+  %vecext = extractelement <4 x i8> %a, i32 0
+  %conv = zext i8 %vecext to i32
+  ret i32 %conv
+}
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