Avoid undef in tests

Author: ostannard

llvm/test/CodeGen/Thumb2/bf16-pcs.ll

@@ -144,7 +144,7 @@ define void @caller_soft_bfloat_on_stack() {
 ; BE-BF16-NEXT:    add sp, #8
 ; BE-BF16-NEXT:    pop {r7, pc}
 entry:
-  %ret = call arm_aapcscc bfloat @callee_soft_bfloat_on_stack(float undef, float undef, float undef, float undef, bfloat 1.0)
+  %ret = call arm_aapcscc bfloat @callee_soft_bfloat_on_stack(float poison, float poison, float poison, float poison, bfloat 1.0)
   ret void
 }
 
@@ -311,6 +311,6 @@ define void @caller_hard_bfloat_on_stack() {
 ; BE-BF16-NEXT:    add sp, #8
 ; BE-BF16-NEXT:    pop {r7, pc}
 entry:
-  %ret = call arm_aapcs_vfpcc bfloat @callee_hard_bfloat_on_stack(float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, bfloat 1.0)
+  %ret = call arm_aapcs_vfpcc bfloat @callee_hard_bfloat_on_stack(float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, bfloat 1.0)
   ret void
 }

llvm/test/CodeGen/Thumb2/fp16-pcs.ll

@@ -140,7 +140,7 @@ define void @caller_soft_half_on_stack() {
 ; BE-FP16-NEXT:    add sp, #8
 ; BE-FP16-NEXT:    pop {r7, pc}
 entry:
-  %ret = call arm_aapcscc half @callee_soft_half_on_stack(float undef, float undef, float undef, float undef, half 1.0)
+  %ret = call arm_aapcscc half @callee_soft_half_on_stack(float poison, float poison, float poison, float poison, half 1.0)
   ret void
 }
 
@@ -283,6 +283,6 @@ define void @caller_hard_half_on_stack() {
 ; BE-FP16-NEXT:    add sp, #8
 ; BE-FP16-NEXT:    pop {r7, pc}
 entry:
-  %ret = call arm_aapcs_vfpcc half @callee_hard_half_on_stack(float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, float undef, half 1.0)
+  %ret = call arm_aapcs_vfpcc half @callee_hard_half_on_stack(float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, float poison, half 1.0)
   ret void
 }