The SPARCv9 ABI returns a float in %f0.

This is different from the argument passing convention which puts the
first float argument in %f1.

With this patch, all returned floats are treated as if the 'inreg' flag
were set. This means multiple float return values get packed in %f0,
%f1, %f2, ...

Note that when returning a struct in registers, clang will set the
'inreg' flag on the return value, so that behavior is unchanged. This
also happens when returning a float _Complex.

llvm-svn: 199028

2 files changed, 12 insertions, 3 deletions

diff --git a/llvm/lib/Target/Sparc/SparcCallingConv.td b/llvm/lib/Target/Sparc/SparcCallingConv.td
index acd4ec21de4..dfaaabf344a 100644
--- a/llvm/lib/Target/Sparc/SparcCallingConv.td
+++ b/llvm/lib/Target/Sparc/SparcCallingConv.td
@@ -103,7 +103,7 @@ def RetCC_Sparc32 : CallingConv<[
 // Function return values are passed exactly like function arguments, except a
 // struct up to 32 bytes in size can be returned in registers.
 
-// Function arguments AND return values.
+// Function arguments AND most return values.
 def CC_Sparc64 : CallingConv<[
   // The frontend uses the inreg flag to indicate i32 and float arguments from
   // structs. These arguments are not promoted to 64 bits, but they can still
@@ -118,6 +118,15 @@ def CC_Sparc64 : CallingConv<[
   CCCustom<"CC_Sparc64_Full">
 ]>;
 
+def RetCC_Sparc64 : CallingConv<[
+  // A single f32 return value always goes in %f0. The ABI doesn't specify what
+  // happens to multiple f32 return values outside a struct.
+  CCIfType<[f32], CCCustom<"CC_Sparc64_Half">>,
+
+  // Otherwise, return values are passed exactly like arguments.
+  CCDelegateTo<CC_Sparc64>
+]>;
+
 // Callee-saved registers are handled by the register window mechanism.
 def CSR : CalleeSavedRegs<(add)> {
   let OtherPreserved = (add (sequence "I%u", 0, 7),
diff --git a/llvm/lib/Target/Sparc/SparcISelLowering.cpp b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
index 2fce971edf5..fce2c0d5b03 100644
--- a/llvm/lib/Target/Sparc/SparcISelLowering.cpp
+++ b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
@@ -254,7 +254,7 @@ SparcTargetLowering::LowerReturn_64(SDValue Chain,
                  DAG.getTarget(), RVLocs, *DAG.getContext());
 
   // Analyze return values.
-  CCInfo.AnalyzeReturn(Outs, CC_Sparc64);
+  CCInfo.AnalyzeReturn(Outs, RetCC_Sparc64);
 
   SDValue Flag;
   SmallVector<SDValue, 4> RetOps(1, Chain);
@@ -1258,7 +1258,7 @@ SparcTargetLowering::LowerCall_64(TargetLowering::CallLoweringInfo &CLI,
   if (CLI.Ins.size() == 1 && CLI.Ins[0].VT == MVT::f32 && CLI.CS == 0)
     CLI.Ins[0].Flags.setInReg();
 
-  RVInfo.AnalyzeCallResult(CLI.Ins, CC_Sparc64);
+  RVInfo.AnalyzeCallResult(CLI.Ins, RetCC_Sparc64);
 
   // Copy all of the result registers out of their specified physreg.
   for (unsigned i = 0; i != RVLocs.size(); ++i) {