From 9cec62a27fe56f1775e23fdae57300edfdfe2699 Mon Sep 17 00:00:00 2001
From: Louis Gerbarg <lgg@apple.com>
Date: Mon, 12 May 2014 19:53:52 +0000
Subject: Add support bswap16 to/from memory compiling to rev16 on ARM/Thumb

The current patterns for REV16 misses mostn __builtin_bswap16() due to
legalization promoting the operands to from load/stores toi32s and then
truncing/extending them. This patch adds new patterns that catch the resultant
DAGs and codegens them to rev16 instructions. Tests included.

rdar://15353652

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208620 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMInstrInfo.td  |  5 +++++
 lib/Target/ARM/ARMInstrThumb.td | 12 ++++++++++++
 test/CodeGen/ARM/bswap16.ll     | 42 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+)
 create mode 100644 test/CodeGen/ARM/bswap16.ll

diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index 82f203e101..1d2a7e1be4 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -4122,6 +4122,11 @@ def REV16 : AMiscA1I<0b01101011, 0b1011, (outs GPR:$Rd), (ins GPR:$Rm),
                Requires<[IsARM, HasV6]>,
            Sched<[WriteALU]>;
 
+def : ARMV6Pat<(srl (bswap (extloadi16 addrmode3:$addr)), (i32 16)),
+              (REV16 (LDRH addrmode3:$addr))>;
+def : ARMV6Pat<(truncstorei16 (srl (bswap GPR:$Rn), (i32 16)), addrmode3:$addr),
+               (STRH (REV16 GPR:$Rn), addrmode3:$addr)>;
+
 let AddedComplexity = 5 in
 def REVSH : AMiscA1I<0b01101111, 0b1011, (outs GPR:$Rd), (ins GPR:$Rm),
                IIC_iUNAr, "revsh", "\t$Rd, $Rm",
diff --git a/lib/Target/ARM/ARMInstrThumb.td b/lib/Target/ARM/ARMInstrThumb.td
index 8c58d40e68..170c2ffab5 100644
--- a/lib/Target/ARM/ARMInstrThumb.td
+++ b/lib/Target/ARM/ARMInstrThumb.td
@@ -1308,6 +1308,18 @@ def : T1Pat<(addc   tGPR:$lhs, imm8_255_neg:$rhs),
 def : T1Pat<(subc   tGPR:$lhs, tGPR:$rhs),
             (tSUBrr tGPR:$lhs, tGPR:$rhs)>;
 
+// Bswap 16 with load/store
+def : T1Pat<(srl (bswap (extloadi16 t_addrmode_rrs2:$addr)), (i32 16)),
+            (tREV16 (tLDRHr t_addrmode_rrs2:$addr))>;
+def : T1Pat<(srl (bswap (extloadi16 t_addrmode_is2:$addr)), (i32 16)),
+            (tREV16 (tLDRHi t_addrmode_is2:$addr))>;
+def : T1Pat<(truncstorei16 (srl (bswap tGPR:$Rn), (i32 16)),
+                           t_addrmode_rrs2:$addr),
+            (tSTRHr (tREV16 tGPR:$Rn), t_addrmode_rrs2:$addr)>;
+def : T1Pat<(truncstorei16 (srl (bswap tGPR:$Rn), (i32 16)),
+                           t_addrmode_is2:$addr),
+            (tSTRHi(tREV16 tGPR:$Rn), t_addrmode_is2:$addr)>;
+
 // ConstantPool
 def : T1Pat<(ARMWrapper  tconstpool  :$dst), (tLEApcrel tconstpool  :$dst)>;
 
diff --git a/test/CodeGen/ARM/bswap16.ll b/test/CodeGen/ARM/bswap16.ll
new file mode 100644
index 0000000000..29cec4f112
--- /dev/null
+++ b/test/CodeGen/ARM/bswap16.ll
@@ -0,0 +1,42 @@
+; RUN: llc -march=arm  -mattr=v6 < %s | FileCheck %s
+; RUN: llc -march=thumb  -mattr=v6 < %s | FileCheck %s
+
+
+define void @test1(i16* nocapture %data) {
+entry:
+  %0 = load i16* %data, align 2
+  %1 = tail call i16 @llvm.bswap.i16(i16 %0)
+  store i16 %1, i16* %data, align 2
+  ret void
+
+  ; CHECK-LABEL: test1:
+  ; CHECK: ldrh r[[R1:[0-9]+]], [r0]
+  ; CHECK: rev16 r[[R1]], r[[R1]]
+  ; CHECK: strh r[[R1]], [r0]
+}
+
+
+define void @test2(i16* nocapture %data, i16 zeroext %in) {
+entry:
+  %0 = tail call i16 @llvm.bswap.i16(i16 %in)
+  store i16 %0, i16* %data, align 2
+  ret void
+
+  ; CHECK-LABEL: test2:
+  ; CHECK: rev16 r[[R1:[0-9]+]], r1
+  ; CHECK: strh r[[R1]], [r0]
+}
+
+
+define i16 @test3(i16* nocapture %data) {
+entry:
+  %0 = load i16* %data, align 2
+  %1 = tail call i16 @llvm.bswap.i16(i16 %0)
+  ret i16 %1
+
+  ; CHECK-LABEL: test3:
+  ; CHECK: ldrh r[[R0:[0-9]+]], [r0]
+  ; CHECK: rev16 r[[R0]], r0
+}
+
+declare i16 @llvm.bswap.i16(i16)
-- 
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