[AMDGPU, test] Fix use of undef FileCheck var

[thopre]

Summary

Test CodeGen/AMDGPU/amdgpu.private-memory.ll and
CodeGen/AMDGPU/private-memory-r600.ll have a block of CHECK directives
whose prefix is inconsistent: R600-CHECK Vs R600. This leads to a
R600-NOT directive using an undefined CHAN variable due to R600-CHECK
directives never being considered by FileCheck. Fixing the prefix leads
to the testcase failing. As per https://reviews.llvm.org/D99865#2675235
this commit removes the directives instead since it is not possible to
write a reliable check.

[arsenm]

It's really hard to write checks for R600, but it's in maintenance mode. The comment doesn't really make sense to me. I doubt this check was ever really correct or stable. You can't really write this test stably and expect specific things in T registers at a specific time. I guess just go with this is it passes?

[thopre]

In D99865#2675176, @arsenm wrote:

It's really hard to write checks for R600, but it's in maintenance mode. The comment doesn't really make sense to me. I doubt this check was ever really correct or stable. You can't really write this test stably and expect specific things in T registers at a specific time. I guess just go with this is it passes?

Unfortunately the test case as updated by this diff FAILs, as can be seen above. Unfortunately the current testcase only succeeds due to a bug in FileCheck which I have a patch for. FileCheck currently count an undefined variable as a match failure which makes a CHECK-NOT with an undefined variable succeed. Does the comment make sense with the old CHECKS (see https://reviews.llvm.org/rG880a80ad07b6ea7ead3a842fc03c74c2247c9486)?

Should we remove those checks altogether?

[arsenm]

In D99865#2675219, @thopre wrote:

In D99865#2675176, @arsenm wrote:

It's really hard to write checks for R600, but it's in maintenance mode. The comment doesn't really make sense to me. I doubt this check was ever really correct or stable. You can't really write this test stably and expect specific things in T registers at a specific time. I guess just go with this is it passes?

Unfortunately the test case as updated by this diff FAILs, as can be seen above. Unfortunately the current testcase only succeeds due to a bug in FileCheck which I have a patch for. FileCheck currently count an undefined variable as a match failure which makes a CHECK-NOT with an undefined variable succeed. Does the comment make sense with the old CHECKS (see https://reviews.llvm.org/rG880a80ad07b6ea7ead3a842fc03c74c2247c9486)?

Should we remove those checks altogether?

Might as well delete them then. I don't know how you can really write a reasonable check for what the comment describes

[thopre]

Remove directives instead

llvm/test/CodeGen/AMDGPU/amdgpu.private-memory.ll

entry:
   %5 = sext i8 %4 to i32
   store i32 %5, i32 addrspace(1)* %out
   ret void
 }
 
 ; Test that two stack objects are not stored in the same register
 ; The second stack object should be in T3.X
 ; FUNC-LABEL: {{^}}no_overlap:
-; R600-CHECK: MOV
-; R600-CHECK: [[CHAN:[XYZW]]]+
+; R600: MOV
+; R600: [[CHAN:[XYZW]]]+
 ; R600-NOT: [[CHAN]]+
 ;
 ; A total of 5 bytes should be allocated and used.
 ; SI: buffer_store_byte v{{[0-9]+}}, off, s[{{[0-9]+:[0-9]+}}], 0 offset:4 ;
 define amdgpu_kernel void @no_overlap(i32 addrspace(1)* %out, i32 %in) #0 {
 entry:
   %0 = alloca [3 x i8], align 1, addrspace(5)
   %1 = alloca [2 x i8], align 1, addrspace(5)

llvm/test/CodeGen/AMDGPU/private-memory-r600.ll

entry:
   %6 = add i32 %4, %5
   store i32 %6, i32 addrspace(1)* %out
   ret void
 }
 
 ; Test that two stack objects are not stored in the same register
 ; The second stack object should be in T3.X
 ; FUNC-LABEL: {{^}}no_overlap:
-; R600_CHECK: MOV
-; R600_CHECK: [[CHAN:[XYZW]]]+
+; R600: MOV
+; R600: [[CHAN:[XYZW]]]+
 ; R600-NOT: [[CHAN]]+
 define amdgpu_kernel void @no_overlap(i32 addrspace(1)* %out, i32 %in) #0 {
 entry:
   %0 = alloca [3 x i8], align 1, addrspace(5)
   %1 = alloca [2 x i8], align 1, addrspace(5)
   %2 = getelementptr inbounds [3 x i8], [3 x i8] addrspace(5)* %0, i32 0, i32 0
   %3 = getelementptr inbounds [3 x i8], [3 x i8] addrspace(5)* %0, i32 0, i32 1
   %4 = getelementptr inbounds [3 x i8], [3 x i8] addrspace(5)* %0, i32 0, i32 2