From: Daniel Sanders <daniel.sanders@imgtec.com>
Date: Mon, 14 Sep 2015 10:12:30 +0000 (+0000)
Subject: Merging r246990:
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9b5d11e278ef32fd453c8050af899837f69e1d99;p=llvm

Merging r246990:
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r246990 | dsanders | 2015-09-08 10:07:03 +0100 (Tue, 08 Sep 2015) | 9 lines

[mips] Reserve address spaces 1-255 for software use.

Summary: And define them to have noop casts with address spaces 0-255.

Reviewers: pekka.jaaskelainen

Subscribers: pekka.jaaskelainen, llvm-commits

Differential Revision: http://reviews.llvm.org/D12678
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_37@247538 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/Mips/MipsISelLowering.h b/lib/Target/Mips/MipsISelLowering.h
index 6fe8f830d35..b3d861d34da 100644
--- a/lib/Target/Mips/MipsISelLowering.h
+++ b/lib/Target/Mips/MipsISelLowering.h
@@ -269,6 +269,14 @@ namespace llvm {
     unsigned getRegisterByName(const char* RegName, EVT VT,
                                SelectionDAG &DAG) const override;
 
+    /// Returns true if a cast between SrcAS and DestAS is a noop.
+    bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const override {
+      // Mips doesn't have any special address spaces so we just reserve
+      // the first 256 for software use (e.g. OpenCL) and treat casts
+      // between them as noops.
+      return SrcAS < 256 && DestAS < 256;
+    }
+
   protected:
     SDValue getGlobalReg(SelectionDAG &DAG, EVT Ty) const;
 
diff --git a/test/CodeGen/Mips/llvm-ir/addrspacecast.ll b/test/CodeGen/Mips/llvm-ir/addrspacecast.ll
new file mode 100644
index 00000000000..060fa4ce7bb
--- /dev/null
+++ b/test/CodeGen/Mips/llvm-ir/addrspacecast.ll
@@ -0,0 +1,12 @@
+; RUN: llc < %s -march=mips -mcpu=mips2 | FileCheck %s -check-prefix=ALL
+
+; Address spaces 1-255 are software defined.
+define i32* @cast(i32 *%arg) {
+  %1 = addrspacecast i32* %arg to i32 addrspace(1)*
+  %2 = addrspacecast i32 addrspace(1)* %1 to i32 addrspace(2)*
+  %3 = addrspacecast i32 addrspace(2)* %2 to i32 addrspace(0)*
+  ret i32* %3
+}
+
+; ALL-LABEL: cast:
+; ALL:           move   $2, $4