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* disable -Warray-bounds in libgo (PR 101374)
@ 2021-07-08 18:02 Martin Sebor
  2021-07-08 21:07 ` Rainer Orth
  2021-07-09  6:16 ` Richard Biener
  0 siblings, 2 replies; 11+ messages in thread
From: Martin Sebor @ 2021-07-08 18:02 UTC (permalink / raw)
  To: Ian Lance Taylor; +Cc: gcc-patches

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Hi Ian,

Yesterday's enhancement to -Warray-bounds has exposed a couple of
issues in libgo where the code writes into an invalid constant
address that the warning is designed to flag.

On the assumption that those invalid addresses are deliberate,
the attached patch suppresses these instances by using #pragma
GCC diagnostic but I don't think I'm supposed to commit it (at
least Git won't let me).  To avoid Go bootstrap failures please
either apply the patch or otherwise suppress the warning (e.g.,
by using a volatile pointer temporary).

Thanks
Martin

[-- Attachment #2: libgo-pr101374.diff --]
[-- Type: text/x-patch, Size: 1646 bytes --]

Use Object Size Type zero for -Warray-bounds [PR101374].

PR bootstrap/101374 - -Warray-bounds accessing a member subobject as derived

libgo/ChangeLog:
	PR bootstrap/101374
	* runtime/proc.c (runtime_mstart): Suppress -Warray-bounds.
	* runtime/runtime_c.c (runtime_signalstack): Same.

diff --git a/libgo/runtime/proc.c b/libgo/runtime/proc.c
index 38bf7a6b255..61635e6c1ea 100644
--- a/libgo/runtime/proc.c
+++ b/libgo/runtime/proc.c
@@ -594,7 +594,14 @@ runtime_mstart(void *arg)
 		gp->entry = nil;
 		gp->param = nil;
 		__builtin_call_with_static_chain(pfn(gp1), fv);
+
+		/* Writing to an invalid address is detected.  */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Warray-bounds"
+
 		*(int*)0x21 = 0x21;
+
+#pragma GCC diagnostic push
 	}
 
 	if(mp->exiting) {
@@ -662,7 +669,12 @@ setGContext(void)
 		gp->entry = nil;
 		gp->param = nil;
 		__builtin_call_with_static_chain(pfn(gp1), fv);
+
+		/* Writing to an invalid address is detected.  */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Warray-bounds"
 		*(int*)0x22 = 0x22;
+#pragma GCC diagnostic pop
 	}
 }
 
diff --git a/libgo/runtime/runtime_c.c b/libgo/runtime/runtime_c.c
index 18222c14465..53feaa075c7 100644
--- a/libgo/runtime/runtime_c.c
+++ b/libgo/runtime/runtime_c.c
@@ -116,7 +116,11 @@ runtime_signalstack(byte *p, uintptr n)
 	if(p == nil)
 		st.ss_flags = SS_DISABLE;
 	if(sigaltstack(&st, nil) < 0)
+	  /* Writing to an invalid address is detected.  */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Warray-bounds"
 		*(int *)0xf1 = 0xf1;
+#pragma GCC diagnostic push
 }
 
 int32 go_open(char *, int32, int32)

^ permalink raw reply	[flat|nested] 11+ messages in thread
end of thread, other threads:[~2021-07-13 18:30 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-08 18:02 disable -Warray-bounds in libgo (PR 101374) Martin Sebor
2021-07-08 21:07 ` Rainer Orth
2021-07-09 13:26   ` Rainer Orth
2021-07-12 16:34     ` Martin Sebor
2021-07-13  7:40       ` Rainer Orth
2021-07-09  6:16 ` Richard Biener
2021-07-09 13:19   ` Maxim Kuvyrkov
2021-07-09 19:46     ` Martin Sebor
2021-07-09 16:37   ` Martin Sebor
2021-07-10  2:49   ` Ian Lance Taylor
2021-07-13 18:30   ` Dimitar Dimitrov

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