[WebAssembly] Fix lowering of varargs functions with non-legal fixed arguments.

CallLoweringInfo's NumFixedArgs field gives the number of fixed arguments
before legalization. The ISD::OutputArg "Outs" array holds legalized
arguments, so when indexing into it to find the non-fixed arguemn, we need
to use the number of arguments after legalization.

Fixes PR37934.

llvm-svn: 335576

2 files changed, 24 insertions, 2 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index 52b1e18c8a4..633af3e8752 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -487,6 +487,7 @@ SDValue WebAssemblyTargetLowering::LowerCall(
 
   SmallVectorImpl<ISD::OutputArg> &Outs = CLI.Outs;
   SmallVectorImpl<SDValue> &OutVals = CLI.OutVals;
+  unsigned NumFixedArgs = 0;
   for (unsigned i = 0; i < Outs.size(); ++i) {
     const ISD::OutputArg &Out = Outs[i];
     SDValue &OutVal = OutVals[i];
@@ -512,11 +513,11 @@ SDValue WebAssemblyTargetLowering::LowerCall(
           /*isTailCall*/ false, MachinePointerInfo(), MachinePointerInfo());
       OutVal = FINode;
     }
+    // Count the number of fixed args *after* legalization.
+    NumFixedArgs += Out.IsFixed;
   }
 
   bool IsVarArg = CLI.IsVarArg;
-  unsigned NumFixedArgs = CLI.NumFixedArgs;
-
   auto PtrVT = getPointerTy(Layout);
 
   // Analyze operands of the call, assigning locations to each operand.
diff --git a/llvm/test/CodeGen/WebAssembly/varargs.ll b/llvm/test/CodeGen/WebAssembly/varargs.ll
index acd35c3b4a9..0e26ab4959b 100644
--- a/llvm/test/CodeGen/WebAssembly/varargs.ll
+++ b/llvm/test/CodeGen/WebAssembly/varargs.ll
@@ -143,6 +143,27 @@ bb1:
   ret void
 }
 
+; Test a call to a varargs function with a non-legal fixed argument.
+
+declare void @callee_with_nonlegal_fixed(fp128, ...) nounwind
+
+; CHECK-LABEL: call_nonlegal_fixed:
+; CHECK: i64.const       $push[[L0:[0-9]+]]=, 0
+; CHECK: i64.const       $push[[L1:[0-9]+]]=, 0
+; CHECK: i32.const       $push[[L2:[0-9]+]]=, 0
+; CHECK: call            callee_with_nonlegal_fixed@FUNCTION, $pop[[L0]], $pop[[L1]], $pop[[L2]]{{$}}
+define void @call_nonlegal_fixed() nounwind {
+  call void (fp128, ...) @callee_with_nonlegal_fixed(fp128 0xL00000000000000000000000000000000)
+  ret void
+}
+
+; Test a definition a varargs function with a non-legal fixed argument.
+
+; CHECK-LABEL: nonlegal_fixed:
+; CHECK-NEXT: .param          i64, i64, i32{{$}}
+define void @nonlegal_fixed(fp128 %x, ...) nounwind {
+  ret void
+}
 
 declare void @llvm.va_start(i8*)
 declare void @llvm.va_end(i8*)