[AArch64]: add 'a' inline asm operand modifier.

Summary:
This is used in the Linux kernel, and effectively just means "print an
address". This brings back r193593.

Reviewed by: Renato Golin

Reviewers: t.p.northover, rengolin, richard.barton.arm, kristof.beyls

Subscribers: aemerson, javed.absar, llvm-commits, eraman

Differential Revision: https://reviews.llvm.org/D33558

llvm-svn: 303901

2 files changed, 11 insertions, 1 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
index 056ffd58b52..981fd22c213 100644
--- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -320,6 +320,9 @@ bool AArch64AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
     switch (ExtraCode[0]) {
     default:
       return true; // Unknown modifier.
+    case 'a':      // Print 'a' modifier
+      PrintAsmMemoryOperand(MI, OpNum, AsmVariant, ExtraCode, O);
+      return false;
     case 'w':      // Print W register
     case 'x':      // Print X register
       if (MO.isReg())
@@ -388,7 +391,7 @@ bool AArch64AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
                                               unsigned AsmVariant,
                                               const char *ExtraCode,
                                               raw_ostream &O) {
-  if (ExtraCode && ExtraCode[0])
+  if (ExtraCode && ExtraCode[0] && ExtraCode[0] != 'a')
     return true; // Unknown modifier.
 
   const MachineOperand &MO = MI->getOperand(OpNum);
diff --git a/llvm/test/CodeGen/AArch64/arm64-inline-asm.ll b/llvm/test/CodeGen/AArch64/arm64-inline-asm.ll
index f28d0ab07c5..f849df2a51e 100644
--- a/llvm/test/CodeGen/AArch64/arm64-inline-asm.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-inline-asm.ll
@@ -254,3 +254,10 @@ define void @test_constraint_w(i32 %a) {
   tail call void asm sideeffect "sqxtn h0, ${0:s}\0A", "w"(i32 %a)
   ret void
 }
+
+define void @test_inline_modifier_a(i8* %ptr) nounwind {
+  ; CHECK-LABEL: test_inline_modifier_a:
+  tail call void asm sideeffect "prfm pldl1keep, ${0:a}\0A", "r"(i8* %ptr)
+  ; CHECK: prfm pldl1keep, [x0]
+  ret void
+}