[PATCH] [AArch64] Teach AsmPrinter about GlobalAddress operands.

[Ahmed Bougacha]

Basic fix for http://llvm.org/bugs/show_bug.cgi?id=22761.

Looking at the ARM counterpart, it handles stuff like ":lower16:" and more interestingly "(PLT)".  Even more interestingly, removing those doesn't break any tests.
I tried to get some more interesting testcases, but I settled on an assert on the target flags, as I couldn't come up with a case where any of those would be set in inline asm (the other way to get to printOperand is the DEBUG_VALUE comment printer, but that's even more constrained).

Examples and pointers welcome!

I don't have a clear picture of the place of AsmPrinter in the grand scheme of things - yet -, so I'll have a second look and update if necessary  (to the ARM version as well, smells like dead code to me).

Thanks,
-Ahmed

http://reviews.llvm.org/D8042

Files:
  lib/Target/AArch64/AArch64AsmPrinter.cpp
  test/CodeGen/AArch64/inline-asm-globaladdress.ll

Index: lib/Target/AArch64/AArch64AsmPrinter.cpp
===================================================================
--- lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -34,6 +34,7 @@
 #include "llvm/MC/MCInstBuilder.h"
 #include "llvm/MC/MCLinkerOptimizationHint.h"
 #include "llvm/MC/MCStreamer.h"
+#include "llvm/MC/MCSymbol.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/TargetRegistry.h"
 using namespace llvm;
@@ -219,6 +220,17 @@
     O << '#' << Imm;
     break;
   }
+  case MachineOperand::MO_GlobalAddress: {
+    const GlobalValue *GV = MO.getGlobal();
+    MCSymbol *Sym = getSymbol(GV);
+
+    // FIXME: Can we get anything other than a plain symbol here?
+    assert(!MO.getTargetFlags() && "Unknown operand target flag!");
+
+    O << *Sym;
+    printOffset(MO.getOffset(), O);
+    break;
+  }
   }
 }
 
Index: test/CodeGen/AArch64/inline-asm-globaladdress.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/inline-asm-globaladdress.ll
@@ -0,0 +1,22 @@
+; RUN: llc < %s -mtriple aarch64-gnu-linux | FileCheck %s --check-prefix=CHECK --check-prefix=LINUX
+; RUN: llc < %s -mtriple arm64-apple-darwin | FileCheck %s --check-prefix=CHECK --check-prefix=DARWIN
+
+target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
+
+; CHECK-LABEL: test_inlineasm_globaladdress:
+; LINUX: b test_symbol
+; DARWIN: b _test_symbol
+define void @test_inlineasm_globaladdress() {
+  call void asm sideeffect "b $0", "i"(void ()* @test_symbol)
+  ret void
+}
+
+; CHECK-LABEL: test_inlineasm_globaladdress_offset:
+; LINUX: b test_symbol+4
+; DARWIN: b _test_symbol+4
+define void @test_inlineasm_globaladdress_offset() {
+  call void asm sideeffect "b $0", "i"(void ()* bitcast (i8* getelementptr (i8* bitcast (void ()* @test_symbol to i8*), i64 4) to void ()*))
+  ret void
+}
+
+declare void @test_symbol()

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