[Lldb-commits] [lldb] [lldb][debugserver] Read/write SME registers on arm64 (PR #119171)

[Jason Molenda via lldb-commits]

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@@ -312,16 +312,21 @@ struct DNBRegisterValue {
     uint64_t uint64;
     float float32;
     double float64;
-    int8_t v_sint8[64];
-    int16_t v_sint16[32];
-    int32_t v_sint32[16];
-    int64_t v_sint64[8];
-    uint8_t v_uint8[64];
-    uint16_t v_uint16[32];
-    uint32_t v_uint32[16];
-    uint64_t v_uint64[8];
-    float v_float32[16];
-    double v_float64[8];
+    // AArch64 SME's ZA register max size is 64k, this object must be
+    // large enough to hold that much data.  The current Apple cores
+    // have a much smaller maximum ZA reg size, but there are not
+    // multiple copies of this object so increase the static size to
+    // maximum possible.
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jasonmolenda wrote:

Yeah, this object is allocated to read/write a single register, so a read of x0 will be a 64k object.  But looking at the debugserver sources, we don't store an array of them anywhere - we read / write individual registers one at a time with this object for a short time period, so I don't think the memory increase is a problem.  It might be better to have a dynamically allocated size here though, as you did.  I did that for the DNBArm64ArchImpl register contexts stored for each thread, where we will have one for each thread when stopped, that memory use made me more nervous.

https://github.com/llvm/llvm-project/pull/119171