[mips] Do not use function CC_MipsN_VarArg unless the function being analyzed

is a vararg function.

The original code was examining flag OutputArg::IsFixed to determine whether
CC_MipsN_VarArg or CC_MipsN should be called. This is not correct, since this
flag is often set to false when the function being analyzed is a non-variadic
function.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174442 91177308-0d34-0410-b5e6-96231b3b80d8

Author: ahatanak

lib/Target/Mips/MipsISelLowering.cpp

@@ -3793,7 +3793,7 @@ MipsTargetLowering::MipsCC::MipsCC(CallingConv::ID CallConv, bool IsVarArg,
     IntArgRegs = Mips64IntRegs;
     ShadowRegs = Mips64DPRegs;
     FixedFn = CC_MipsN;
-    VarFn = CC_MipsN_VarArg;
+    VarFn = IsVarArg ? CC_MipsN_VarArg : CC_MipsN;
   }
 
   if (CallConv == CallingConv::Fast) {

test/CodeGen/Mips/mips64-expand-libcall.ll

@@ -0,0 +1,14 @@
+; RUN: llc -march=mips64el -mcpu=mips64r2 -O3 < %s | FileCheck %s
+
+; Check that %add is not passed in an integer register.
+;
+; CHECK-NOT: dmfc1 $4
+
+define double @callfloor(double %d) nounwind readnone {
+entry:
+  %add = fadd double %d, 1.000000e+00
+  %call = tail call double @floor(double %add) nounwind readnone
+  ret double %call
+}
+
+declare double @floor(double) nounwind readnone