================
@@ -232,13 +232,23 @@ bool AArch64TargetInfo::validateTarget(DiagnosticsEngine
&Diags) const {
bool AArch64TargetInfo::validateGlobalRegisterVariable(
StringRef RegName, unsigned RegSize, bool &HasSizeMismatch) const {
- if ((RegName == "sp") || RegName.starts_with("x")) {
- HasSizeMismatch = RegSize != 64;
- return true;
- } else if (RegName.starts_with("w")) {
+ if (RegName.starts_with("w")) {
HasSizeMismatch = RegSize != 32;
return true;
}
+ if (RegName == "sp") {
+ HasSizeMismatch = RegSize != 64;
+ return true;
+ }
+ if (RegName.starts_with("x")) {
+ HasSizeMismatch = RegSize != 64;
+ // Check if the register is reserved. See also
+ // AArch64TargetLowering::getRegisterByName().
+ return RegName == "x0" ||
+ (RegName == "x18" &&
+ llvm::AArch64::isX18ReservedByDefault(getTriple())) ||
+ getTargetOpts().FeatureMap.lookup(("reserve-" + RegName).str());
----------------
kawashima-fj wrote:
To avoid the `fatal error: error in backend: Invalid register name "x??"` error
in #109778, this check is sufficient.
I think the original purpose of rejecting a global register variable associated
with a non-reserved register is to avoid unintended register use. `w??`
registers are lower half bits of the corresponding `x??` registers. So when
`x??` register is not reserved, should we reject a global register variable
associated with the corresponding `w??`?
For this purpose, maybe [the
backend](https://github.com/llvm/llvm-project/blob/bc28260/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp#L11611)
should also check `w??` registers. Actually, [old backend code checked `w??`
regsters](https://github.com/llvm/llvm-project/commit/fcbec02ea6fb2a76352b64790cd9ae300f6a9943#diff-6291e4657dea1f4fecdcb9dc96bfb014f79d4c617f080b2f033943e52732cf69).
https://github.com/llvm/llvm-project/pull/117419
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