[clang] [flang] [Flang][Driver]Implemented support for option -momit-leaf-frame-pointer/-mno-omit-leaf-frame-pointer in flang (PR #216700)

[Tarun Prabhu via cfe-commits]

================
@@ -10,3 +10,36 @@
 
 ! RUN: %flang -fno-omit-frame-pointer --target=x86-none-none -fsyntax-only -### %s -o %t 2>&1  | FileCheck %s --check-prefix=CHECK-ALLFP
 ! CHECK-ALLFP: "-fc1"{{.*}}"-mframe-pointer=all"
+
+! // =======
+
+! Default behavior in x86_64-unknown-linux-gnu, -mframe-pointer=all at -O0 level.
+
+! RUN: %flang -O0 --target=x86_64-unknown-linux-gnu -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-ALL
+! RUN: %flang -O0 -momit-leaf-frame-pointer --target=x86_64-unknown-linux-gnu -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-NON-LEAF
+! RUN: %flang -O0 -mno-omit-leaf-frame-pointer --target=x86_64-unknown-linux-gnu -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-ALL
+! RUN: %flang -O0 -fomit-frame-pointer -momit-leaf-frame-pointer --target=x86_64-unknown-linux-gnu -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-NONE
+! RUN: %flang -fno-omit-frame-pointer -momit-leaf-frame-pointer -mno-omit-leaf-frame-pointer --target=x86_64-unknown-linux-gnu -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-ALL
+
+! Default behavior in x86_64-unknown-linux-gnu, -mframe-pointer=none at -O1/-O2/-O3 level.
+! RUN: %flang --target=x86_64-unknown-linux-gnu -O2 -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-NONE
+
+! With -fno-omit-frame-pointer and -mno-omit-leaf-frame-pointer, -mframe-pointer=all.
+! RUN: %flang -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer --target=x86_64-unknown-linux-gnu -O2 -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-ALL
+
+! Without -fno-omit-frame-pointer the leaf option is silently allowed but has no effect, matching Clang's behavior.
+! RUN: %flang -momit-leaf-frame-pointer --target=x86_64-unknown-linux-gnu -O2 -### %s -o %t 2>&1  | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-NONE
+! RUN: %flang -fno-omit-frame-pointer --target=x86_64-unknown-linux-gnu -O2 -### %s -o %t 2>&1 | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-ALL
+
+! RUN: %flang -fno-omit-frame-pointer -momit-leaf-frame-pointer --target=x86_64-unknown-linux-gnu -O2 -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-NON-LEAF
+
+! Default behavior in aarch64-none-none, -mframe-pointer=non-leaf-no-reserve.
+! RUN: %flang -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer --target=aarch64-none-none -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-FRAME-POINTER-ALL
+
+! CHECK-FRAME-POINTER-ALL: "-fc1"
+! CHECK-FRAME-POINTER-ALL-SAME: "-mframe-pointer=all"
+! CHECK-FRAME-POINTER-NON-LEAF: "-fc1"
+! CHECK-FRAME-POINTER-NON-LEAF-SAME: "-mframe-pointer=non-leaf-no-reserve"
----------------
tarunprabhu wrote:

Instead of replicating the check for `-fc1`, consider doing something like this:

```
FRAME-POINTER-COMMON: "-fc1"
FRAME-POINTER-NON-LEAF-SAME: "-mframe-pointer=non-leaf-no-reserve"
FRAME-POINTER-NONE-SAME: "-mframe-pointer=none"
```

IIUC, the `-SAME` checks work even if the previous match was against a different prefix, as long as both matches are on the same line. 

You would have to modify the run lines to check for multiple prefixes

```
RUN: ... | FileCheck %s --check-prefixes=FRAME-POINTER-COMMON,FRAME-POINTER-NONE
```

This is for your consideration. If you would prefer to stick with the current approach, that is fine too.

https://github.com/llvm/llvm-project/pull/216700