[llvm] [Matrix] Add a Remark when matrices get flattened (PR #142078)

[Jon Roelofs via llvm-commits]

================
@@ -573,6 +695,61 @@ entry:
 }
 
 define void @multiply_ntt_t(ptr %A, ptr %B, ptr %C, ptr %R) {
+; REMARK-LABEL: Name:            unknown-shape-lowering-def
+; REMARK-NEXT: Function:        multiply_ntt_t
+; REMARK-NEXT: Args:
+; REMARK-NEXT:   - String:          'splitting a '
+; REMARK-NEXT:   - Rows:            '3'
+; REMARK-NEXT:   - String:          x
+; REMARK-NEXT:   - Cols:            '3'
+; REMARK-NEXT:   - String:          ' matrix '
+; REMARK-NEXT:   - String:          ' with '
+; REMARK-NEXT:   - Shuffles:        '3'
+; REMARK-NEXT:   - String:          ' shuffles because we do not have a shape-aware lowering for its def: '
+; REMARK-NEXT:   - Instr:           call
+; REMARK-NEXT:   - Opcode:          call
+; REMARK-NEXT: ...
+; REMARK-LABEL: Name:            unknown-shape-lowering-def
+; REMARK-NEXT: Function:        multiply_ntt_t
+; REMARK-NEXT: Args:
+; REMARK-NEXT:   - String:          'splitting a '
+; REMARK-NEXT:   - Rows:            '3'
+; REMARK-NEXT:   - String:          x
+; REMARK-NEXT:   - Cols:            '3'
+; REMARK-NEXT:   - String:          ' matrix '
+; REMARK-NEXT:   - String:          ' with '
+; REMARK-NEXT:   - Shuffles:        '3'
+; REMARK-NEXT:   - String:          ' shuffles because we do not have a shape-aware lowering for its def: '
+; REMARK-NEXT:   - Instr:           load
+; REMARK-NEXT:   - Opcode:          load
+; REMARK-NEXT: ...
+; REMARK-LABEL: Name:            unknown-shape-lowering-use
+; REMARK-NEXT: Function:        multiply_ntt_t
+; REMARK-NEXT: Args:
+; REMARK-NEXT:   - String:          'flattening a '
+; REMARK-NEXT:   - Rows:            '3'
+; REMARK-NEXT:   - String:          x
+; REMARK-NEXT:   - Cols:            '3'
+; REMARK-NEXT:   - String:          ' matrix '
+; REMARK-NEXT:   - Source:          '  %{{.*}} = load <9 x double>, ptr %A, align 16'
----------------
jroelofs wrote:

```suggestion
; REMARK-NEXT:   - Source:          '  %{{.*}} = load <9 x double>, ptr %{{.*}}, align 16'
```

https://github.com/llvm/llvm-project/pull/142078