[PowerPC] Fix on-stack AltiVec arguments with 64-bit SVR4

Current 64-bit SVR4 code seems to have some remnants of Darwin code
in AltiVec argument handing.  This had the effect that AltiVec arguments
(or subsequent arguments) were not correctly placed in the parameter area
in some cases.

The correct behaviour with the 64-bit SVR4 ABI is:
- All AltiVec arguments take up space in the parameter area, just like
  any other arguments, whether vararg or not.
- They are always 16-byte aligned, skipping a parameter area doubleword
  (and the associated GPR, if any), if necessary.

This patch implements the correct behaviour and adds a test case.
(Verified against GCC behaviour via the ABI compat test suite.)



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211492 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 25 insertions, 0 deletions

diff --git a/test/CodeGen/PowerPC/ppc64-altivec-abi.ll b/test/CodeGen/PowerPC/ppc64-altivec-abi.ll
new file mode 100644
index 0000000000..0bed329f0e
--- /dev/null
+++ b/test/CodeGen/PowerPC/ppc64-altivec-abi.ll
@@ -0,0 +1,25 @@
+; RUN: llc < %s -march=ppc64 -mattr=+altivec | FileCheck %s
+
+target datalayout = "E-m:e-i64:64-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+; Verify that in the 64-bit Linux ABI, vector arguments take up space
+; in the parameter save area.
+
+define i64 @callee(i64 %a, <4 x i32> %b, i64 %c, <4 x i32> %d, i64 %e) {
+entry:
+  ret i64 %e
+}
+; CHECK-LABEL: callee:
+; CHECK: ld 3, 112(1)
+
+define void @caller(i64 %x, <4 x i32> %y) {
+entry:
+  tail call void @test(i64 %x, <4 x i32> %y, i64 %x, <4 x i32> %y, i64 %x)
+  ret void
+}
+; CHECK-LABEL: caller:
+; CHECK: std 3, 112(1)
+
+declare void @test(i64, <4 x i32>, i64, <4 x i32>, i64)
+