[PPC] [NFC] add testcase for more store forwarding

Author: Chen Zheng

llvm/test/CodeGen/PowerPC/legalize-vaarg.ll

@@ -1,6 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ;RUN: llc < %s --mtriple=powerpc64-unknown-linux-gnu -mattr=+altivec | FileCheck %s -check-prefix=BE
 ;RUN: llc < %s --mtriple=powerpc64le-unknown-linux-gnu -mattr=+altivec | FileCheck %s -check-prefix=LE
+;RUN: llc < %s --mtriple=powerpc64-unknown-linux-gnu -mattr=+altivec -ppc-gather-alias-max-depth=0 | FileCheck %s -check-prefix=FORWARD
 
 define <8 x i32> @test_large_vec_vaarg(i32 %n, ...) {
 ; BE-LABEL: test_large_vec_vaarg:
@@ -35,6 +36,22 @@ define <8 x i32> @test_large_vec_vaarg(i32 %n, ...) {
 ; LE-NEXT:    lxvd2x 0, 0, 3
 ; LE-NEXT:    xxswapd 35, 0
 ; LE-NEXT:    blr
+;
+; FORWARD-LABEL: test_large_vec_vaarg:
+; FORWARD:       # %bb.0:
+; FORWARD-NEXT:    ld 3, -8(1)
+; FORWARD-NEXT:    addi 3, 3, 15
+; FORWARD-NEXT:    rldicr 3, 3, 0, 59
+; FORWARD-NEXT:    addi 4, 3, 16
+; FORWARD-NEXT:    std 4, -8(1)
+; FORWARD-NEXT:    ld 4, -8(1)
+; FORWARD-NEXT:    lvx 2, 0, 3
+; FORWARD-NEXT:    addi 4, 4, 15
+; FORWARD-NEXT:    rldicr 3, 4, 0, 59
+; FORWARD-NEXT:    addi 4, 3, 16
+; FORWARD-NEXT:    std 4, -8(1)
+; FORWARD-NEXT:    lvx 3, 0, 3
+; FORWARD-NEXT:    blr
   %args = alloca ptr, align 4
   %x = va_arg ptr %args, <8 x i32>
   ret <8 x i32> %x