Fix PR20056: Implement pseudo LDR <reg>, =<literal/label> for AArch64

This patch is based on the changes from ARM target [1,2]

Based on ARM doc [3], if the literal value can be loaded with a valid MOV,
it can emit that instruction. This is implemented in this patch.

[1] Fix PR18345: ldr= pseudo instruction produces incorrect code when using in inline assembly
Author: David Peixotto <dpeixott@codeaurora.org>
commit b92cca222898d87bbc764fa22e805adb04ef7f13 (r200777)
[2] Implement the ldr-pseudo opcode for ARM assembly
Author: David Peixotto <dpeixott@codeaurora.org>
commit 0fa193b08627927ccaa0804a34d80480894614b8 (r197708)
[3] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0802a/CJAHAIBC.html

Differential Revision: http://reviews.llvm.org/D4163


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211533 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 21 insertions, 0 deletions

diff --git a/include/llvm/MC/MCStreamer.h b/include/llvm/MC/MCStreamer.h
index bf224979de..cd1fa9b6a8 100644
--- a/include/llvm/MC/MCStreamer.h
+++ b/include/llvm/MC/MCStreamer.h
@@ -86,6 +86,27 @@ public:
   virtual void finish();
 };
 
+class AArch64TargetStreamer : public MCTargetStreamer {
+public:
+  AArch64TargetStreamer(MCStreamer &S);
+  ~AArch64TargetStreamer();
+
+
+  void finish() override;
+
+  /// Callback used to implement the ldr= pseudo.
+  /// Add a new entry to the constant pool for the current section and return an
+  /// MCExpr that can be used to refer to the constant pool location.
+  const MCExpr *addConstantPoolEntry(const MCExpr *);
+
+  /// Callback used to implemnt the .ltorg directive.
+  /// Emit contents of constant pool for the current section.
+  void emitCurrentConstantPool();
+
+private:
+  std::unique_ptr<AssemblerConstantPools> ConstantPools;
+};
+
 // FIXME: declared here because it is used from
 // lib/CodeGen/AsmPrinter/ARMException.cpp.
 class ARMTargetStreamer : public MCTargetStreamer {