[AArch64] Implement support for windows style vararg functions

Pass parameters properly in calls to such functions (pass all
floats in integer registers), and handle va_start properly (allocate
stack immediately below the arguments on the stack, to save the
register arguments into a single continuous array).

Differential Revision: https://reviews.llvm.org/D35006

llvm-svn: 307928

1 files changed, 95 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/AArch64/win64_vararg.ll b/llvm/test/CodeGen/AArch64/win64_vararg.ll
new file mode 100644
index 00000000000..b760e4acd16
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/win64_vararg.ll
@@ -0,0 +1,95 @@
+; RUN: llc < %s -mtriple=aarch64-pc-win32 | FileCheck %s
+
+define void @pass_va(i32 %count, ...) nounwind {
+entry:
+; CHECK: sub     sp, sp, #80
+; CHECK: add     x8, sp, #24
+; CHECK: add     x0, sp, #24
+; CHECK: stp     x6, x7, [sp, #64]
+; CHECK: stp     x4, x5, [sp, #48]
+; CHECK: stp     x2, x3, [sp, #32]
+; CHECK: str     x1, [sp, #24]
+; CHECK: stp     x30, x8, [sp]
+; CHECK: bl      other_func
+; CHECK: ldr     x30, [sp], #80
+; CHECK: ret
+  %ap = alloca i8*, align 8
+  %ap1 = bitcast i8** %ap to i8*
+  call void @llvm.va_start(i8* %ap1)
+  %ap2 = load i8*, i8** %ap, align 8
+  call void @other_func(i8* %ap2)
+  ret void
+}
+
+declare void @other_func(i8*) local_unnamed_addr
+
+declare void @llvm.va_start(i8*) nounwind
+declare void @llvm.va_copy(i8*, i8*) nounwind
+
+; CHECK-LABEL: f9:
+; CHECK: sub     sp, sp, #16
+; CHECK: add     x8, sp, #24
+; CHECK: add     x0, sp, #24
+; CHECK: str     x8, [sp, #8]
+; CHECK: add     sp, sp, #16
+; CHECK: ret
+define i8* @f9(i64 %a0, i64 %a1, i64 %a2, i64 %a3, i64 %a4, i64 %a5, i64 %a6, i64 %a7, i64 %a8, ...) nounwind {
+entry:
+  %ap = alloca i8*, align 8
+  %ap1 = bitcast i8** %ap to i8*
+  call void @llvm.va_start(i8* %ap1)
+  %ap2 = load i8*, i8** %ap, align 8
+  ret i8* %ap2
+}
+
+; CHECK-LABEL: f8:
+; CHECK: sub     sp, sp, #16
+; CHECK: add     x8, sp, #16
+; CHECK: add     x0, sp, #16
+; CHECK: str     x8, [sp, #8]
+; CHECK: add     sp, sp, #16
+; CHECK: ret
+define i8* @f8(i64 %a0, i64 %a1, i64 %a2, i64 %a3, i64 %a4, i64 %a5, i64 %a6, i64 %a7, ...) nounwind {
+entry:
+  %ap = alloca i8*, align 8
+  %ap1 = bitcast i8** %ap to i8*
+  call void @llvm.va_start(i8* %ap1)
+  %ap2 = load i8*, i8** %ap, align 8
+  ret i8* %ap2
+}
+
+; CHECK-LABEL: f7:
+; CHECK: sub     sp, sp, #16
+; CHECK: add     x8, sp, #8
+; CHECK: add     x0, sp, #8
+; CHECK: stp     x8, x7, [sp], #16
+; CHECK: ret
+define i8* @f7(i64 %a0, i64 %a1, i64 %a2, i64 %a3, i64 %a4, i64 %a5, i64 %a6, ...) nounwind {
+entry:
+  %ap = alloca i8*, align 8
+  %ap1 = bitcast i8** %ap to i8*
+  call void @llvm.va_start(i8* %ap1)
+  %ap2 = load i8*, i8** %ap, align 8
+  ret i8* %ap2
+}
+
+; CHECK-LABEL: copy1:
+; CHECK: sub     sp, sp, #80
+; CHECK: add     x8, sp, #24
+; CHECK: stp     x6, x7, [sp, #64]
+; CHECK: stp     x4, x5, [sp, #48]
+; CHECK: stp     x2, x3, [sp, #32]
+; CHECK: stp     x8, x1, [sp, #16]
+; CHECK: str     x8, [sp, #8]
+; CHECK: add     sp, sp, #80
+; CHECK: ret
+define void @copy1(i64 %a0, ...) nounwind {
+entry:
+  %ap = alloca i8*, align 8
+  %cp = alloca i8*, align 8
+  %ap1 = bitcast i8** %ap to i8*
+  %cp1 = bitcast i8** %cp to i8*
+  call void @llvm.va_start(i8* %ap1)
+  call void @llvm.va_copy(i8* %cp1, i8* %ap1)
+  ret void
+}