[llvm] r288296 - [WebAssembly] Emit .import_global assembler directives

[Derek Schuff via llvm-commits]

Author: dschuff
Date: Wed Nov 30 18:11:15 2016
New Revision: 288296

URL: http://llvm.org/viewvc/llvm-project?rev=288296&view=rev
Log:
[WebAssembly] Emit .import_global assembler directives

Support a new assembler directive, .import_global, to declare imported
global variables (i.e. those with external linkage and no
initializer). The linker turns these into wasm imports.

Patch by Jacob Gravelle

Differential Revision: https://reviews.llvm.org/D26875

Modified:
    llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
    llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
    llvm/trunk/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
    llvm/trunk/test/CodeGen/WebAssembly/globl.ll

Modified: llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp?rev=288296&r1=288295&r2=288296&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp Wed Nov 30 18:11:15 2016
@@ -80,6 +80,10 @@ void WebAssemblyTargetAsmStreamer::emitI
   OS << '\n';
 }
 
+void WebAssemblyTargetAsmStreamer::emitGlobalImport(StringRef name) {
+  OS << "\t.import_global\t" << name << '\n';
+}
+
 void WebAssemblyTargetAsmStreamer::emitIndIdx(const MCExpr *Value) {
   OS << "\t.indidx  \t" << *Value << '\n';
 }
@@ -111,3 +115,6 @@ void WebAssemblyTargetELFStreamer::emitI
   // Nothing to emit here. TODO: Re-design how linking works and re-evaluate
   // whether it's necessary for .o files to declare indirect function types.
 }
+
+void WebAssemblyTargetELFStreamer::emitGlobalImport(StringRef name) {
+}
\ No newline at end of file

Modified: llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h?rev=288296&r1=288295&r2=288296&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h (original)
+++ llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h Wed Nov 30 18:11:15 2016
@@ -45,6 +45,8 @@ public:
   }
   /// .indidx
   virtual void emitIndIdx(const MCExpr *Value) = 0;
+  /// .import_global
+  virtual void emitGlobalImport(StringRef name) = 0;
 };
 
 /// This part is for ascii assembly output
@@ -62,6 +64,7 @@ public:
                                 SmallVectorImpl<MVT> &Params,
                                 SmallVectorImpl<MVT> &Results) override;
   void emitIndIdx(const MCExpr *Value) override;
+  void emitGlobalImport(StringRef name) override;
 };
 
 /// This part is for ELF object output
@@ -77,6 +80,7 @@ public:
                                 SmallVectorImpl<MVT> &Params,
                                 SmallVectorImpl<MVT> &Results) override;
   void emitIndIdx(const MCExpr *Value) override;
+  void emitGlobalImport(StringRef name) override;
 };
 
 } // end namespace llvm

Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp?rev=288296&r1=288295&r2=288296&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp Wed Nov 30 18:11:15 2016
@@ -133,6 +133,11 @@ void WebAssemblyAsmPrinter::EmitEndOfAsm
                                                     Results);
     }
   }
+  for (const auto &G : M.globals()) {
+    if (!G.hasInitializer() && G.hasExternalLinkage()) {
+      getTargetStreamer()->emitGlobalImport(G.getGlobalIdentifier());
+    }
+  }
 }
 
 void WebAssemblyAsmPrinter::EmitConstantPool() {

Modified: llvm/trunk/test/CodeGen/WebAssembly/globl.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/globl.ll?rev=288296&r1=288295&r2=288296&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/globl.ll (original)
+++ llvm/trunk/test/CodeGen/WebAssembly/globl.ll Wed Nov 30 18:11:15 2016
@@ -8,3 +8,7 @@ target triple = "wasm32-unknown-unknown"
 define void @foo() {
   ret void
 }
+
+; Check import directives - must be at the end of the file
+; CHECK: .import_global bar{{$}}
+ at bar = external global i32