[X86] When using Win64 ABI, exit with error if SSE is disabled for varargs

We need XMM registers to handle varargs with the Win64 ABI. Before we would
silently generate bad code resulting in an assertion failure elsewhere in the
backend.

llvm-svn: 357317

2 files changed, 20 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index a5691cdfc6a..6f9caf1d0bb 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -3780,6 +3780,9 @@ X86TargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
     } else if (VA.isRegLoc()) {
       RegsToPass.push_back(std::make_pair(VA.getLocReg(), Arg));
       if (isVarArg && IsWin64) {
+        if (!Subtarget.hasSSE1())
+          errorUnsupported(
+              DAG, dl, "Win64 ABI varargs functions require SSE to be enabled");
         // Win64 ABI requires argument XMM reg to be copied to the corresponding
         // shadow reg if callee is a varargs function.
         unsigned ShadowReg = 0;
diff --git a/llvm/test/CodeGen/X86/win64-nosse-error.ll b/llvm/test/CodeGen/X86/win64-nosse-error.ll
new file mode 100644
index 00000000000..0d22adf0a79
--- /dev/null
+++ b/llvm/test/CodeGen/X86/win64-nosse-error.ll
@@ -0,0 +1,17 @@
+; RUN: not --crash llc %s -mattr="-sse" 2>&1 | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-macho"
+
+; Function Attrs: noimplicitfloat noinline noredzone nounwind optnone
+define void @crash() #0 {
+  call void (i32*, ...) @func(i32* null, double undef)
+  ret void
+}
+; CHECK: in function crash void (): Win64 ABI varargs functions require SSE to be enabled
+; Function Attrs: noimplicitfloat noredzone
+declare void @func(i32*, ...)
+
+attributes #0 = { "target-cpu"="x86-64" "target-features"="-sse"}
+
+