From 2ddeeed096d8a6570fd57b9a5f62732ddb88d477 Mon Sep 17 00:00:00 2001
From: Tim Northover <tnorthover@apple.com>
Date: Thu, 22 Aug 2013 06:51:04 +0000
Subject: [PATCH] ARM: respect tied 64-bit inlineasm operands when printing

The code for 'Q' and 'R' operand modifiers needs to look through tied
operands to discover the register class.

llvm-svn: 188990
---
 llvm/lib/Target/ARM/ARMAsmPrinter.cpp    | 17 +++++++++++++++++
 llvm/test/CodeGen/ARM/inlineasm-64bit.ll | 10 ++++++++++
 2 files changed, 27 insertions(+)

diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index 13a22b1..485b1c5 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -496,6 +496,23 @@ bool ARMAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
       if (!FlagsOP.isImm())
         return true;
       unsigned Flags = FlagsOP.getImm();
+
+      // This operand may not be the one that actually provides the register. If
+      // it's tied to a previous one then we should refer instead to that one
+      // for registers and their classes.
+      unsigned TiedIdx;
+      if (InlineAsm::isUseOperandTiedToDef(Flags, TiedIdx)) {
+        for (OpNum = InlineAsm::MIOp_FirstOperand; TiedIdx; --TiedIdx) {
+          unsigned OpFlags = MI->getOperand(OpNum).getImm();
+          OpNum += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
+        }
+        Flags = MI->getOperand(OpNum).getImm();
+
+        // Later code expects OpNum to be pointing at the register rather than
+        // the flags.
+        OpNum += 1;
+      }
+
       unsigned NumVals = InlineAsm::getNumOperandRegisters(Flags);
       unsigned RC;
       InlineAsm::hasRegClassConstraint(Flags, RC);
diff --git a/llvm/test/CodeGen/ARM/inlineasm-64bit.ll b/llvm/test/CodeGen/ARM/inlineasm-64bit.ll
index 69b3860..683a0c4 100644
--- a/llvm/test/CodeGen/ARM/inlineasm-64bit.ll
+++ b/llvm/test/CodeGen/ARM/inlineasm-64bit.ll
@@ -94,3 +94,13 @@ define i64 @tied_64bit_test(i64 %in) nounwind {
   call void asm "OUT($0), IN($1)", "=*rm,0"(i64* %addr, i64 %in)
   ret i64 %in
 }
+
+; If we explicitly name a tied operand, then the code should lookup the operand
+; we were tied to for information about register class and so on.
+define i64 @tied_64bit_lookback_test(i64 %in) nounwind {
+; CHECK-LABEL: tied_64bit_lookback_test:
+; CHECK: OUTLO([[LO:r[0-9]+]]) OUTHI([[HI:r[0-9]+]]) INLO([[LO]]) INHI([[HI]])
+  %vars = call {i64, i32, i64} asm "OUTLO(${2:Q}) OUTHI(${2:R}) INLO(${3:Q}) INHI(${3:R})", "=r,=r,=r,2"(i64 %in)
+  %res = extractvalue {i64, i32, i64} %vars, 2
+  ret i64 %res
+}
-- 
2.7.4