https://github.com/DavidSpickett created
https://github.com/llvm/llvm-project/pull/140875
Recently the Linux Kernel has fixed a bunch of issues in SME support and while
testing that, I found two tests failing: FAIL:
test_za_register_dynamic_config_main_disabled
(TestZAThreadedDynamic.AArch64ZAThreadedTestCase) FAIL:
test_za_register_dynamic_config_main_enabled
(TestZAThreadedDynamic.AArch64ZAThreadedTestCase)
These tests write to vg during streaming mode from lldb and expect to see that
za has been resized to match it. Instead, it was unavilable. lldb-server was
sending the correct amount of data but lldb client was expect the old size.
Turns out that instead of a write to vg invalidating svg, it was
invalidating... something else. I'm still not sure how these tests ever worked
but with this one line fix, they pass again.
I did not see this issue with SVE or streaming SVE Z registers because those
always resize using the value of vg, and vg always has the value we just wrote.
(remember that vg is the vector length of the **current** mode, not of
non-streaming mode, whereas svg is the vector length of streaming mode, even if
you are currently in non-streaming mode)
>From e91a16b051193d3d66228901bae9419e02238d72 Mon Sep 17 00:00:00 2001
From: David Spickett <david.spick...@linaro.org>
Date: Wed, 21 May 2025 09:57:26 +0000
Subject: [PATCH] [lldb][AArch64] Correctly invalidate svg when vg is written
Recently the Linux Kernel has fixed a bunch of issues in SME support
and while testing that, I found two tests failing:
FAIL: test_za_register_dynamic_config_main_disabled
(TestZAThreadedDynamic.AArch64ZAThreadedTestCase)
FAIL: test_za_register_dynamic_config_main_enabled
(TestZAThreadedDynamic.AArch64ZAThreadedTestCase)
These tests write to vg during streaming mode from lldb and expect to see that
za has been
resized to match it. Instead, it was unavilable. lldb-server was sending
the correct amount of data but lldb client was expect the old size.
Turns out that instead of a write to vg invalidating svg, it was invalidating...
something else. I'm still not sure how these tests ever worked but
with this one line fix, they pass again.
I did not see this issue with SVE or streaming SVE Z registers because
those always resize using the value of vg, and vg always has the value we
just wrote.
(remember that vg is the vector length of the **current** mode,
not of non-streaming mode, whereas svg is the vector length of streaming
mode, even if you are currently in non-streaming mode)
---
lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp
b/lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp
index c004c0f3c3cf5..f2095c150609f 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp
@@ -425,7 +425,7 @@ void RegisterInfoPOSIX_arm64::AddRegSetSME(bool has_zt) {
//
// This must be added now, rather than when vg is defined because SME is a
// dynamic set that may or may not be present.
- static uint32_t vg_invalidates[] = {sme_regnum + 1 /*svg*/,
+ static uint32_t vg_invalidates[] = {first_sme_regnum + 1 /*svg*/,
LLDB_INVALID_REGNUM};
m_dynamic_reg_infos[GetRegNumSVEVG()].invalidate_regs = vg_invalidates;
}
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