From f470cbbad204caa85275873004151b92fba24375 Mon Sep 17 00:00:00 2001
From: Chad Rosier <mcrosier@apple.com>
Date: Fri, 4 Nov 2011 00:50:21 +0000
Subject: [PATCH] Add fast-isel support for returning i1, i8, and i16.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143669 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMFastISel.cpp    | 25 ++++++++++++----
 test/CodeGen/ARM/fast-isel-ret.ll | 48 +++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 6 deletions(-)
 create mode 100644 test/CodeGen/ARM/fast-isel-ret.ll

diff --git a/lib/Target/ARM/ARMFastISel.cpp b/lib/Target/ARM/ARMFastISel.cpp
index d1f2c7fcdd2..ab5caa3d5eb 100644
--- a/lib/Target/ARM/ARMFastISel.cpp
+++ b/lib/Target/ARM/ARMFastISel.cpp
@@ -1751,19 +1751,32 @@ bool ARMFastISel::SelectRet(const Instruction *I) {
     CCValAssign &VA = ValLocs[0];
 
     // Don't bother handling odd stuff for now.
-    // FIXME: Should be able to handle i1, i8, and/or i16 return types.
     if (VA.getLocInfo() != CCValAssign::Full)
       return false;
     // Only handle register returns for now.
     if (!VA.isRegLoc())
       return false;
-    // TODO: For now, don't try to handle cases where getLocInfo()
-    // says Full but the types don't match.
-    if (TLI.getValueType(RV->getType()) != VA.getValVT())
-      return false;
+
+    unsigned SrcReg = Reg + VA.getValNo();
+    EVT RVVT = TLI.getValueType(RV->getType());
+    EVT DestVT = VA.getValVT();
+    // Special handling for extended integers.
+    if (RVVT != DestVT) {
+      if (RVVT != MVT::i1 && RVVT != MVT::i8 && RVVT != MVT::i16)
+        return false;
+
+      if (!Outs[0].Flags.isZExt() && !Outs[0].Flags.isSExt())
+        return false;
+
+      assert(DestVT == MVT::i32 && "ARM should always ext to i32");
+
+      bool isZExt = Outs[0].Flags.isZExt();
+      unsigned ResultReg = ARMEmitIntExt(RVVT, SrcReg, DestVT, isZExt);
+      if (ResultReg == 0) return false;
+      SrcReg = ResultReg;
+    }
 
     // Make the copy.
-    unsigned SrcReg = Reg + VA.getValNo();
     unsigned DstReg = VA.getLocReg();
     const TargetRegisterClass* SrcRC = MRI.getRegClass(SrcReg);
     // Avoid a cross-class copy. This is very unlikely.
diff --git a/test/CodeGen/ARM/fast-isel-ret.ll b/test/CodeGen/ARM/fast-isel-ret.ll
new file mode 100644
index 00000000000..f7f4521c8dd
--- /dev/null
+++ b/test/CodeGen/ARM/fast-isel-ret.ll
@@ -0,0 +1,48 @@
+; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=armv7-apple-darwin | FileCheck %s
+; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=thumbv7-apple-darwin | FileCheck %s
+
+; Sign-extend of i1 currently not supported by fast-isel
+;define signext i1 @ret0(i1 signext %a) nounwind uwtable ssp {
+;entry:
+;  ret i1 %a
+;}
+
+define zeroext i1 @ret1(i1 signext %a) nounwind uwtable ssp {
+entry:
+; CHECK: ret1
+; CHECK: and r0, r0, #1
+; CHECK: bx lr
+  ret i1 %a
+}
+
+define signext i8 @ret2(i8 signext %a) nounwind uwtable ssp {
+entry:
+; CHECK: ret2
+; CHECK: sxtb r0, r0
+; CHECK: bx lr
+  ret i8 %a
+}
+
+define zeroext i8 @ret3(i8 signext %a) nounwind uwtable ssp {
+entry:
+; CHECK: ret3
+; CHECK: uxtb r0, r0
+; CHECK: bx lr
+  ret i8 %a
+}
+
+define signext i16 @ret4(i16 signext %a) nounwind uwtable ssp {
+entry:
+; CHECK: ret4
+; CHECK: sxth r0, r0
+; CHECK: bx lr
+  ret i16 %a
+}
+
+define zeroext i16 @ret5(i16 signext %a) nounwind uwtable ssp {
+entry:
+; CHECK: ret5
+; CHECK: uxth r0, r0
+; CHECK: bx lr
+  ret i16 %a
+}