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target/arm: Introduce PREDDESC field definitions

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SVE predicate operations cannot use the "usual" simd_desc
encoding, because the lengths are not a multiple of 8.
But we were abusing the SIMD_* fields to store values anyway.
This abuse broke when SIMD_OPRSZ_BITS was modified in e2e7168a21.

Introduce a new set of field definitions for exclusive use
of predicates, so that it is obvious what kind of predicate
we are manipulating.  To be used in future patches.

Cc: qemu-stable@nongnu.org
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210113062650.593824-2-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Richard Henderson 2021-01-12 20:26:47 -10:00 committed by Peter Maydell
parent bc944d3a8b
commit b64ee454a4
1 changed files with 9 additions and 0 deletions
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9
target/arm/internals.h
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@ -1348,6 +1348,15 @@ void arm_log_exception(int idx);
#define LOG2_TAG_GRANULE 4
#define TAG_GRANULE (1 << LOG2_TAG_GRANULE)
/*
* SVE predicates are 1/8 the size of SVE vectors, and cannot use
* the same simd_desc() encoding due to restrictions on size.
* Use these instead.
*/
FIELD(PREDDESC, OPRSZ, 0, 6)
FIELD(PREDDESC, ESZ, 6, 2)
FIELD(PREDDESC, DATA, 8, 24)
/*
* The SVE simd_data field, for memory ops, contains either
* rd (5 bits) or a shift count (2 bits).