[Qemu-devel] [Bug 1824853] Re: 4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] == off' failed
** Changed in: qemu
Status: Fix Committed => Fix Released
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Title:
4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion
`s->gen_insn_end_off[num_insns] == off' failed
Status in QEMU:
Fix Released
Bug description:
I tried to bootstrap and regtested gcc trunk (gcc svn rev 270278,
datestamp 20190411) inside my arm64-gentoo installation under qemu-
system-aarch64.
Qemu version was 4.0.0-rc3 and -cpu cortex-a57. Qemu configured with
only --target-list=aarch64-softmmu,aarch64-linux-user and compiled
using gcc "version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1~16.04)".
Executable created from gcc/testsuite/gcc.target/aarch64/advsimd-
intrinsics/vldX.c compiled with -O2 crashed the whole qemu-system.
To investigate a bit I also manually run
~/gcc/inst/trunk/bin/gcc
~/gcc/src/trunk/gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vldX.c
with different options like:
-O0 -lm -o d0.exe
-O1 -lm -o d1.exe
-O2 -lm -o d2.exe
-O0 -static -lm -o s0.exe
-O1 -static -lm -o s1.exe
-O2 -static -lm -o s2.exe
So, now I have 6 different arm64 executables created with different
optimization levels. O0 and O1 versions run ok.
Three sN.exe static executables I've also tried in qemu user mode (with same
-cpu), no issue in user mode.
And inside qemu-system I can see that
running "d2.exe" (attached) gives:
tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] ==
off' failed.
And running "s2.exe" gives:
tcg/tcg.c:320: set_jmp_reset_offset: Assertion `s->tb_jmp_reset_offset[which]
== off' failed.
It seems like this test is an counter-example for logic that
"tcg_ctx->nb_ops < 4000" implies tcg will fit into 16-bit signed size
(see tcg_op_buf_full comments).
Richard's changes in abebf92597186 and 9f754620651d were not enough,
translation block must be smaller, or we have to find some proper way to bail
out when buffer overflows.
I don't know why this situation is not caught by code_gen_highwater logic in
tcg.c
I've also tried this "bail out" patch
diff --git a/tcg/tcg.c b/tcg/tcg.c
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -3949,7 +3949,8 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
size_t off = tcg_current_code_size(s);
s->gen_insn_end_off[num_insns] = off;
/* Assert that we do not overflow our stored offset. */
-assert(s->gen_insn_end_off[num_insns] == off);
+if (s->gen_insn_end_off[num_insns] != off)
+ return -1;
}
num_insns++;
for (i = 0; i < TARGET_INSN_START_WORDS; ++i) {
But then running "d2.exe" just hangs the whole qemu-system. It seems
that when tcg_gen_code return -1 (like in highwater logic mentioned
before), we just re-call it again and again.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1824853/+subscriptions
[Qemu-devel] [Bug 1824853] Re: 4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] == off' failed
** Tags added: testcase
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Title:
4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion
`s->gen_insn_end_off[num_insns] == off' failed
Status in QEMU:
Fix Committed
Bug description:
I tried to bootstrap and regtested gcc trunk (gcc svn rev 270278,
datestamp 20190411) inside my arm64-gentoo installation under qemu-
system-aarch64.
Qemu version was 4.0.0-rc3 and -cpu cortex-a57. Qemu configured with
only --target-list=aarch64-softmmu,aarch64-linux-user and compiled
using gcc "version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1~16.04)".
Executable created from gcc/testsuite/gcc.target/aarch64/advsimd-
intrinsics/vldX.c compiled with -O2 crashed the whole qemu-system.
To investigate a bit I also manually run
~/gcc/inst/trunk/bin/gcc
~/gcc/src/trunk/gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vldX.c
with different options like:
-O0 -lm -o d0.exe
-O1 -lm -o d1.exe
-O2 -lm -o d2.exe
-O0 -static -lm -o s0.exe
-O1 -static -lm -o s1.exe
-O2 -static -lm -o s2.exe
So, now I have 6 different arm64 executables created with different
optimization levels. O0 and O1 versions run ok.
Three sN.exe static executables I've also tried in qemu user mode (with same
-cpu), no issue in user mode.
And inside qemu-system I can see that
running "d2.exe" (attached) gives:
tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] ==
off' failed.
And running "s2.exe" gives:
tcg/tcg.c:320: set_jmp_reset_offset: Assertion `s->tb_jmp_reset_offset[which]
== off' failed.
It seems like this test is an counter-example for logic that
"tcg_ctx->nb_ops < 4000" implies tcg will fit into 16-bit signed size
(see tcg_op_buf_full comments).
Richard's changes in abebf92597186 and 9f754620651d were not enough,
translation block must be smaller, or we have to find some proper way to bail
out when buffer overflows.
I don't know why this situation is not caught by code_gen_highwater logic in
tcg.c
I've also tried this "bail out" patch
diff --git a/tcg/tcg.c b/tcg/tcg.c
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -3949,7 +3949,8 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
size_t off = tcg_current_code_size(s);
s->gen_insn_end_off[num_insns] = off;
/* Assert that we do not overflow our stored offset. */
-assert(s->gen_insn_end_off[num_insns] == off);
+if (s->gen_insn_end_off[num_insns] != off)
+ return -1;
}
num_insns++;
for (i = 0; i < TARGET_INSN_START_WORDS; ++i) {
But then running "d2.exe" just hangs the whole qemu-system. It seems
that when tcg_gen_code return -1 (like in highwater logic mentioned
before), we just re-call it again and again.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1824853/+subscriptions
[Qemu-devel] [Bug 1824853] Re: 4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] == off' failed
The fix should now be in git master (commits 8b86d6d25807e13a6 and
6e6c4efed995d9ec), so it will be in the 4.1 release.
** Changed in: qemu
Status: In Progress => Fix Committed
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Title:
4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion
`s->gen_insn_end_off[num_insns] == off' failed
Status in QEMU:
Fix Committed
Bug description:
I tried to bootstrap and regtested gcc trunk (gcc svn rev 270278,
datestamp 20190411) inside my arm64-gentoo installation under qemu-
system-aarch64.
Qemu version was 4.0.0-rc3 and -cpu cortex-a57. Qemu configured with
only --target-list=aarch64-softmmu,aarch64-linux-user and compiled
using gcc "version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1~16.04)".
Executable created from gcc/testsuite/gcc.target/aarch64/advsimd-
intrinsics/vldX.c compiled with -O2 crashed the whole qemu-system.
To investigate a bit I also manually run
~/gcc/inst/trunk/bin/gcc
~/gcc/src/trunk/gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vldX.c
with different options like:
-O0 -lm -o d0.exe
-O1 -lm -o d1.exe
-O2 -lm -o d2.exe
-O0 -static -lm -o s0.exe
-O1 -static -lm -o s1.exe
-O2 -static -lm -o s2.exe
So, now I have 6 different arm64 executables created with different
optimization levels. O0 and O1 versions run ok.
Three sN.exe static executables I've also tried in qemu user mode (with same
-cpu), no issue in user mode.
And inside qemu-system I can see that
running "d2.exe" (attached) gives:
tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] ==
off' failed.
And running "s2.exe" gives:
tcg/tcg.c:320: set_jmp_reset_offset: Assertion `s->tb_jmp_reset_offset[which]
== off' failed.
It seems like this test is an counter-example for logic that
"tcg_ctx->nb_ops < 4000" implies tcg will fit into 16-bit signed size
(see tcg_op_buf_full comments).
Richard's changes in abebf92597186 and 9f754620651d were not enough,
translation block must be smaller, or we have to find some proper way to bail
out when buffer overflows.
I don't know why this situation is not caught by code_gen_highwater logic in
tcg.c
I've also tried this "bail out" patch
diff --git a/tcg/tcg.c b/tcg/tcg.c
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -3949,7 +3949,8 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
size_t off = tcg_current_code_size(s);
s->gen_insn_end_off[num_insns] = off;
/* Assert that we do not overflow our stored offset. */
-assert(s->gen_insn_end_off[num_insns] == off);
+if (s->gen_insn_end_off[num_insns] != off)
+ return -1;
}
num_insns++;
for (i = 0; i < TARGET_INSN_START_WORDS; ++i) {
But then running "d2.exe" just hangs the whole qemu-system. It seems
that when tcg_gen_code return -1 (like in highwater logic mentioned
before), we just re-call it again and again.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1824853/+subscriptions
[Qemu-devel] [Bug 1824853] Re: 4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] == off' failed
Unfortunately the fix is too big for this point in the 4.0 release
cycle; it'll go into 4.1.
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Title:
4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion
`s->gen_insn_end_off[num_insns] == off' failed
Status in QEMU:
In Progress
Bug description:
I tried to bootstrap and regtested gcc trunk (gcc svn rev 270278,
datestamp 20190411) inside my arm64-gentoo installation under qemu-
system-aarch64.
Qemu version was 4.0.0-rc3 and -cpu cortex-a57. Qemu configured with
only --target-list=aarch64-softmmu,aarch64-linux-user and compiled
using gcc "version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1~16.04)".
Executable created from gcc/testsuite/gcc.target/aarch64/advsimd-
intrinsics/vldX.c compiled with -O2 crashed the whole qemu-system.
To investigate a bit I also manually run
~/gcc/inst/trunk/bin/gcc
~/gcc/src/trunk/gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vldX.c
with different options like:
-O0 -lm -o d0.exe
-O1 -lm -o d1.exe
-O2 -lm -o d2.exe
-O0 -static -lm -o s0.exe
-O1 -static -lm -o s1.exe
-O2 -static -lm -o s2.exe
So, now I have 6 different arm64 executables created with different
optimization levels. O0 and O1 versions run ok.
Three sN.exe static executables I've also tried in qemu user mode (with same
-cpu), no issue in user mode.
And inside qemu-system I can see that
running "d2.exe" (attached) gives:
tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] ==
off' failed.
And running "s2.exe" gives:
tcg/tcg.c:320: set_jmp_reset_offset: Assertion `s->tb_jmp_reset_offset[which]
== off' failed.
It seems like this test is an counter-example for logic that
"tcg_ctx->nb_ops < 4000" implies tcg will fit into 16-bit signed size
(see tcg_op_buf_full comments).
Richard's changes in abebf92597186 and 9f754620651d were not enough,
translation block must be smaller, or we have to find some proper way to bail
out when buffer overflows.
I don't know why this situation is not caught by code_gen_highwater logic in
tcg.c
I've also tried this "bail out" patch
diff --git a/tcg/tcg.c b/tcg/tcg.c
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -3949,7 +3949,8 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
size_t off = tcg_current_code_size(s);
s->gen_insn_end_off[num_insns] = off;
/* Assert that we do not overflow our stored offset. */
-assert(s->gen_insn_end_off[num_insns] == off);
+if (s->gen_insn_end_off[num_insns] != off)
+ return -1;
}
num_insns++;
for (i = 0; i < TARGET_INSN_START_WORDS; ++i) {
But then running "d2.exe" just hangs the whole qemu-system. It seems
that when tcg_gen_code return -1 (like in highwater logic mentioned
before), we just re-call it again and again.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1824853/+subscriptions
[Qemu-devel] [Bug 1824853] Re: 4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] == off' failed
Richard, thank you for solving this so fast!
I certainly can confirm attached executables work fine for me on patched
version.
I'll also re-run full gcc regtest a bit later, but it runs for a rather
long time, not sure this result will be important next week.
Hopefully, patchset will be included into 4 release.
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Title:
4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion
`s->gen_insn_end_off[num_insns] == off' failed
Status in QEMU:
In Progress
Bug description:
I tried to bootstrap and regtested gcc trunk (gcc svn rev 270278,
datestamp 20190411) inside my arm64-gentoo installation under qemu-
system-aarch64.
Qemu version was 4.0.0-rc3 and -cpu cortex-a57. Qemu configured with
only --target-list=aarch64-softmmu,aarch64-linux-user and compiled
using gcc "version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1~16.04)".
Executable created from gcc/testsuite/gcc.target/aarch64/advsimd-
intrinsics/vldX.c compiled with -O2 crashed the whole qemu-system.
To investigate a bit I also manually run
~/gcc/inst/trunk/bin/gcc
~/gcc/src/trunk/gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vldX.c
with different options like:
-O0 -lm -o d0.exe
-O1 -lm -o d1.exe
-O2 -lm -o d2.exe
-O0 -static -lm -o s0.exe
-O1 -static -lm -o s1.exe
-O2 -static -lm -o s2.exe
So, now I have 6 different arm64 executables created with different
optimization levels. O0 and O1 versions run ok.
Three sN.exe static executables I've also tried in qemu user mode (with same
-cpu), no issue in user mode.
And inside qemu-system I can see that
running "d2.exe" (attached) gives:
tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] ==
off' failed.
And running "s2.exe" gives:
tcg/tcg.c:320: set_jmp_reset_offset: Assertion `s->tb_jmp_reset_offset[which]
== off' failed.
It seems like this test is an counter-example for logic that
"tcg_ctx->nb_ops < 4000" implies tcg will fit into 16-bit signed size
(see tcg_op_buf_full comments).
Richard's changes in abebf92597186 and 9f754620651d were not enough,
translation block must be smaller, or we have to find some proper way to bail
out when buffer overflows.
I don't know why this situation is not caught by code_gen_highwater logic in
tcg.c
I've also tried this "bail out" patch
diff --git a/tcg/tcg.c b/tcg/tcg.c
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -3949,7 +3949,8 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
size_t off = tcg_current_code_size(s);
s->gen_insn_end_off[num_insns] = off;
/* Assert that we do not overflow our stored offset. */
-assert(s->gen_insn_end_off[num_insns] == off);
+if (s->gen_insn_end_off[num_insns] != off)
+ return -1;
}
num_insns++;
for (i = 0; i < TARGET_INSN_START_WORDS; ++i) {
But then running "d2.exe" just hangs the whole qemu-system. It seems
that when tcg_gen_code return -1 (like in highwater logic mentioned
before), we just re-call it again and again.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1824853/+subscriptions
[Qemu-devel] [Bug 1824853] Re: 4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] == off' failed
Patch set posted:
https://patchwork.ozlabs.org/project/qemu-devel/list/?series=102978
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Title:
4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion
`s->gen_insn_end_off[num_insns] == off' failed
Status in QEMU:
In Progress
Bug description:
I tried to bootstrap and regtested gcc trunk (gcc svn rev 270278,
datestamp 20190411) inside my arm64-gentoo installation under qemu-
system-aarch64.
Qemu version was 4.0.0-rc3 and -cpu cortex-a57. Qemu configured with
only --target-list=aarch64-softmmu,aarch64-linux-user and compiled
using gcc "version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1~16.04)".
Executable created from gcc/testsuite/gcc.target/aarch64/advsimd-
intrinsics/vldX.c compiled with -O2 crashed the whole qemu-system.
To investigate a bit I also manually run
~/gcc/inst/trunk/bin/gcc
~/gcc/src/trunk/gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vldX.c
with different options like:
-O0 -lm -o d0.exe
-O1 -lm -o d1.exe
-O2 -lm -o d2.exe
-O0 -static -lm -o s0.exe
-O1 -static -lm -o s1.exe
-O2 -static -lm -o s2.exe
So, now I have 6 different arm64 executables created with different
optimization levels. O0 and O1 versions run ok.
Three sN.exe static executables I've also tried in qemu user mode (with same
-cpu), no issue in user mode.
And inside qemu-system I can see that
running "d2.exe" (attached) gives:
tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] ==
off' failed.
And running "s2.exe" gives:
tcg/tcg.c:320: set_jmp_reset_offset: Assertion `s->tb_jmp_reset_offset[which]
== off' failed.
It seems like this test is an counter-example for logic that
"tcg_ctx->nb_ops < 4000" implies tcg will fit into 16-bit signed size
(see tcg_op_buf_full comments).
Richard's changes in abebf92597186 and 9f754620651d were not enough,
translation block must be smaller, or we have to find some proper way to bail
out when buffer overflows.
I don't know why this situation is not caught by code_gen_highwater logic in
tcg.c
I've also tried this "bail out" patch
diff --git a/tcg/tcg.c b/tcg/tcg.c
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -3949,7 +3949,8 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
size_t off = tcg_current_code_size(s);
s->gen_insn_end_off[num_insns] = off;
/* Assert that we do not overflow our stored offset. */
-assert(s->gen_insn_end_off[num_insns] == off);
+if (s->gen_insn_end_off[num_insns] != off)
+ return -1;
}
num_insns++;
for (i = 0; i < TARGET_INSN_START_WORDS; ++i) {
But then running "d2.exe" just hangs the whole qemu-system. It seems
that when tcg_gen_code return -1 (like in highwater logic mentioned
before), we just re-call it again and again.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1824853/+subscriptions
[Qemu-devel] [Bug 1824853] Re: 4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] == off' failed
Returning -1 does not help because all that signals that the buffer is full.
We then flush the buffer and try again, assuming the at the buffer will not
fill.
Given that the buffer is usually many megabytes, this is reasonable.
We need something different to signal that the buffer is not full, but that
another offset has overflowed.
** Changed in: qemu
Status: New => Confirmed
** Changed in: qemu
Status: Confirmed => In Progress
** Changed in: qemu
Assignee: (unassigned) => Richard Henderson (rth)
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Title:
4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion
`s->gen_insn_end_off[num_insns] == off' failed
Status in QEMU:
In Progress
Bug description:
I tried to bootstrap and regtested gcc trunk (gcc svn rev 270278,
datestamp 20190411) inside my arm64-gentoo installation under qemu-
system-aarch64.
Qemu version was 4.0.0-rc3 and -cpu cortex-a57. Qemu configured with
only --target-list=aarch64-softmmu,aarch64-linux-user and compiled
using gcc "version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1~16.04)".
Executable created from gcc/testsuite/gcc.target/aarch64/advsimd-
intrinsics/vldX.c compiled with -O2 crashed the whole qemu-system.
To investigate a bit I also manually run
~/gcc/inst/trunk/bin/gcc
~/gcc/src/trunk/gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vldX.c
with different options like:
-O0 -lm -o d0.exe
-O1 -lm -o d1.exe
-O2 -lm -o d2.exe
-O0 -static -lm -o s0.exe
-O1 -static -lm -o s1.exe
-O2 -static -lm -o s2.exe
So, now I have 6 different arm64 executables created with different
optimization levels. O0 and O1 versions run ok.
Three sN.exe static executables I've also tried in qemu user mode (with same
-cpu), no issue in user mode.
And inside qemu-system I can see that
running "d2.exe" (attached) gives:
tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] ==
off' failed.
And running "s2.exe" gives:
tcg/tcg.c:320: set_jmp_reset_offset: Assertion `s->tb_jmp_reset_offset[which]
== off' failed.
It seems like this test is an counter-example for logic that
"tcg_ctx->nb_ops < 4000" implies tcg will fit into 16-bit signed size
(see tcg_op_buf_full comments).
Richard's changes in abebf92597186 and 9f754620651d were not enough,
translation block must be smaller, or we have to find some proper way to bail
out when buffer overflows.
I don't know why this situation is not caught by code_gen_highwater logic in
tcg.c
I've also tried this "bail out" patch
diff --git a/tcg/tcg.c b/tcg/tcg.c
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -3949,7 +3949,8 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
size_t off = tcg_current_code_size(s);
s->gen_insn_end_off[num_insns] = off;
/* Assert that we do not overflow our stored offset. */
-assert(s->gen_insn_end_off[num_insns] == off);
+if (s->gen_insn_end_off[num_insns] != off)
+ return -1;
}
num_insns++;
for (i = 0; i < TARGET_INSN_START_WORDS; ++i) {
But then running "d2.exe" just hangs the whole qemu-system. It seems
that when tcg_gen_code return -1 (like in highwater logic mentioned
before), we just re-call it again and again.
To manage notifications about this bug go to:
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[Qemu-devel] [Bug 1824853] Re: 4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] == off' failed
Also attaching static-compiled executable "s2.exe".
** Attachment added: "s2.exe"
https://bugs.launchpad.net/qemu/+bug/1824853/+attachment/5256000/+files/s2.exe
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https://bugs.launchpad.net/bugs/1824853
Title:
4.0.0-rc3 crashes with tcg/tcg.c:3952: tcg_gen_code: Assertion
`s->gen_insn_end_off[num_insns] == off' failed
Status in QEMU:
New
Bug description:
I tried to bootstrap and regtested gcc trunk (gcc svn rev 270278,
datestamp 20190411) inside my arm64-gentoo installation under qemu-
system-aarch64.
Qemu version was 4.0.0-rc3 and -cpu cortex-a57. Qemu configured with
only --target-list=aarch64-softmmu,aarch64-linux-user and compiled
using gcc "version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1~16.04)".
Executable created from gcc/testsuite/gcc.target/aarch64/advsimd-
intrinsics/vldX.c compiled with -O2 crashed the whole qemu-system.
To investigate a bit I also manually run
~/gcc/inst/trunk/bin/gcc
~/gcc/src/trunk/gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vldX.c
with different options like:
-O0 -lm -o d0.exe
-O1 -lm -o d1.exe
-O2 -lm -o d2.exe
-O0 -static -lm -o s0.exe
-O1 -static -lm -o s1.exe
-O2 -static -lm -o s2.exe
So, now I have 6 different arm64 executables created with different
optimization levels. O0 and O1 versions run ok.
Three sN.exe static executables I've also tried in qemu user mode (with same
-cpu), no issue in user mode.
And inside qemu-system I can see that
running "d2.exe" (attached) gives:
tcg/tcg.c:3952: tcg_gen_code: Assertion `s->gen_insn_end_off[num_insns] ==
off' failed.
And running "s2.exe" gives:
tcg/tcg.c:320: set_jmp_reset_offset: Assertion `s->tb_jmp_reset_offset[which]
== off' failed.
It seems like this test is an counter-example for logic that
"tcg_ctx->nb_ops < 4000" implies tcg will fit into 16-bit signed size
(see tcg_op_buf_full comments).
Richard's changes in abebf92597186 and 9f754620651d were not enough,
translation block must be smaller, or we have to find some proper way to bail
out when buffer overflows.
I don't know why this situation is not caught by code_gen_highwater logic in
tcg.c
I've also tried this "bail out" patch
diff --git a/tcg/tcg.c b/tcg/tcg.c
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -3949,7 +3949,8 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
size_t off = tcg_current_code_size(s);
s->gen_insn_end_off[num_insns] = off;
/* Assert that we do not overflow our stored offset. */
-assert(s->gen_insn_end_off[num_insns] == off);
+if (s->gen_insn_end_off[num_insns] != off)
+ return -1;
}
num_insns++;
for (i = 0; i < TARGET_INSN_START_WORDS; ++i) {
But then running "d2.exe" just hangs the whole qemu-system. It seems
that when tcg_gen_code return -1 (like in highwater logic mentioned
before), we just re-call it again and again.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1824853/+subscriptions
