[llvm] [AArch64] Cache AArch64RegisterInfo::isAnyArgRegReserved (PR #190957)

[Cullen Rhodes via llvm-commits]

================
@@ -577,9 +577,18 @@ bool AArch64RegisterInfo::isStrictlyReservedReg(const MachineFunction &MF,
 }
 
 bool AArch64RegisterInfo::isAnyArgRegReserved(const MachineFunction &MF) const {
-  return llvm::any_of(*AArch64::GPR64argRegClass.MC, [this, &MF](MCPhysReg r) {
-    return isStrictlyReservedReg(MF, r);
-  });
+  auto *AFI = MF.getInfo<AArch64FunctionInfo>();
+  if (std::optional<bool> Cached = AFI->getAnyArgRegReserved())
+    return *Cached;
+
+  bool Any =
+      llvm::any_of(*AArch64::GPR64argRegClass.MC, [this, &MF](MCPhysReg r) {
+        return isStrictlyReservedReg(MF, r);
+      });
+  // Re-computing this in getStrictlyReservedRegs during call lowering for
+  // every call is compile-time expensive, so we avoid by caching the result.
+  AFI->setAnyArgRegReserved(Any);
+  return Any;
----------------
c-rhodes wrote:

you're right it's even quicker with your suggestion:
```
; before
(venv) ➜  llvm-test-suite python compare.py build-compiletime-O0-g-baseline-4d84263b341c/ build-compiletime-O0-g-change-4d84263b341c
                 instructions:u                  diff
                            old           new
7zip               140022021530  139850327981  -0.12%
Bullet              65172328835   64954915055  -0.33%
ClamAV              15886698906   15793020981  -0.59%
SPASS               15695354968   15465953482  -1.46%
consumer-typeset    14355883636   14304383550  -0.36%
kimwitu++           24541806601   24387733012  -0.63%
lencod              14626735118   14580929747  -0.31%
mafft                7866559349    7832468344  -0.43%
sqlite3              5634773669    5580341706  -0.97%
tramp3d-v4          22007582844   21796957376  -0.96%
geomean             20222655758   20097861695  -0.62%

; after

(venv) ➜  llvm-test-suite python compare.py build-compiletime-O0-g-baseline-4d84263b341c build-compiletime-O0-g-change-4d84263b341c
                 instructions:u                  diff
                            old           new
7zip               140022021530  139799061361  -0.16%
Bullet              65172328835   64910868166   -0.4%
ClamAV              15886698906   15790883733   -0.6%
SPASS               15695354968   15433651331  -1.67%
consumer-typeset    14355883636   14300038446  -0.39%
kimwitu++           24541806601   24327598025  -0.87%
lencod              14626735118   14573100351  -0.37%
mafft                7866559349    7830498704  -0.46%
sqlite3              5634773669    5570387186  -1.14%
tramp3d-v4          22007582844   21750044121  -1.17%
geomean             20222655758   20076223104  -0.72%
```

https://github.com/llvm/llvm-project/pull/190957