Fix signal handling for platforms without SA_ONSTACK

[vvchernov]

Some platforms such as QNX do not define or implement SA_ONSTACK, so default that flag to 0 to just use the pre-existing stack there.

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[llvmbot]

@llvm/pr-subscribers-llvm-support

Author: Valery Chernov (vvchernov)

Changes

Some platforms such as QNX do not define or implement SA_ONSTACK, so default that flag to 0 to just use the pre-existing stack there.

---

Full diff: https://github.com/llvm/llvm-project/pull/118962.diff

1 Files Affected:

• (modified) llvm/lib/Support/Unix/Signals.inc (+6)

diff --git a/llvm/lib/Support/Unix/Signals.inc b/llvm/lib/Support/Unix/Signals.inc
index 088ca33e3c8c56..3a79246b5f14b8 100644
--- a/llvm/lib/Support/Unix/Signals.inc
+++ b/llvm/lib/Support/Unix/Signals.inc
@@ -309,6 +309,12 @@ static void RegisterHandlers() { // Not signal-safe.
 
     struct sigaction NewHandler;
 
+#ifndef SA_ONSTACK
+    // Some platforms such as QNX do not define or implement SA_ONSTACK,
+    // so default that flag to 0 to just use the pre-existing stack there.
+    int SA_ONSTACK = 0;
+#endif
+
     switch (Kind) {
     case SignalKind::IsKill:
       NewHandler.sa_handler = SignalHandler;

[vvchernov]

cc @AlexMaclean

[vvchernov]

cc @Artem-B

[Artem-B]

I have no context for this change. Based on the folks CC'ed, it may have something to do with NVPTX back-end, but I don't quite see how it may be related to QNX.

[vvchernov]

I have no context for this change. Based on the folks CC'ed, it may have something to do with NVPTX back-end, but I don't quite see how it may be related to QNX.

Hello @Artem-B! May be do you know who can review it?

[Artem-B]

Check who made meaningful commits to https://github.com/llvm/llvm-project/blob/main/llvm/lib/Support/Unix/Signals.inc and who reviewed those changes. That would be a good starting point.

[vvchernov]

@boomanaiden154 @s-barannikov could you review this small patch, please?