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From: Peter Maydell <peter.maydell@linaro.org>
To: qemu-arm@nongnu.org, qemu-devel@nongnu.org
Cc: "Eric Auger" <eric.auger@redhat.com>,
	"Aaron Lindsay" <aaron@os.amperecomputing.com>,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: [PATCH v2 03/21] target/arm: Add isar_feature_any_fp16 and document naming/usage conventions
Date: Fri, 14 Feb 2020 17:50:58 +0000
Message-ID: <20200214175116.9164-4-peter.maydell@linaro.org> (raw)
In-Reply-To: <20200214175116.9164-1-peter.maydell@linaro.org>

Our current usage of the isar_feature feature tests almost always
uses an _aa32_ test when the code path is known to be AArch32
specific and an _aa64_ test when the code path is known to be
AArch64 specific. There is just one exception: in the vfp_set_fpscr
helper we check aa64_fp16 to determine whether the FZ16 bit in
the FP(S)CR exists, but this code is also used for AArch32.
There are other places in future where we're likely to want
a general "does this feature exist for either AArch32 or
AArch64" check (typically where architecturally the feature exists
for both CPU states if it exists at all, but the CPU might be
AArch32-only or AArch64-only, and so only have one set of ID
registers).

Introduce a new category of isar_feature_* functions:
isar_feature_any_foo() should be tested when what we want to
know is "does this feature exist for either AArch32 or AArch64",
and always returns the logical OR of isar_feature_aa32_foo()
and isar_feature_aa64_foo().

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/cpu.h        | 19 ++++++++++++++++++-
 target/arm/vfp_helper.c |  2 +-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 37d40e57901..7ccd65bdce3 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -3328,7 +3328,16 @@ extern const uint64_t pred_esz_masks[4];
  * Naming convention for isar_feature functions:
  * Functions which test 32-bit ID registers should have _aa32_ in
  * their name. Functions which test 64-bit ID registers should have
- * _aa64_ in their name.
+ * _aa64_ in their name. These must only be used in code where we
+ * know for certain that the CPU has AArch32 or AArch64 respectively
+ * or where the correct answer for a CPU which doesn't implement that
+ * CPU state is "false" (eg when generating A32 or A64 code, if adding
+ * system registers that are specific to that CPU state, for "should
+ * we let this system register bit be set" tests where the 32-bit
+ * flavour of the register doesn't have the bit, and so on).
+ * Functions which simply ask "does this feature exist at all" have
+ * _any_ in their name, and always return the logical OR of the _aa64_
+ * and the _aa32_ function.
  */
 
 /*
@@ -3660,6 +3669,14 @@ static inline bool isar_feature_aa64_bti(const ARMISARegisters *id)
     return FIELD_EX64(id->id_aa64pfr1, ID_AA64PFR1, BT) != 0;
 }
 
+/*
+ * Feature tests for "does this exist in either 32-bit or 64-bit?"
+ */
+static inline bool isar_feature_any_fp16(const ARMISARegisters *id)
+{
+    return isar_feature_aa64_fp16(id) || isar_feature_aa32_fp16_arith(id);
+}
+
 /*
  * Forward to the above feature tests given an ARMCPU pointer.
  */
diff --git a/target/arm/vfp_helper.c b/target/arm/vfp_helper.c
index 0ae7d4f34a9..930d6e747f6 100644
--- a/target/arm/vfp_helper.c
+++ b/target/arm/vfp_helper.c
@@ -185,7 +185,7 @@ uint32_t vfp_get_fpscr(CPUARMState *env)
 void HELPER(vfp_set_fpscr)(CPUARMState *env, uint32_t val)
 {
     /* When ARMv8.2-FP16 is not supported, FZ16 is RES0.  */
-    if (!cpu_isar_feature(aa64_fp16, env_archcpu(env))) {
+    if (!cpu_isar_feature(any_fp16, env_archcpu(env))) {
         val &= ~FPCR_FZ16;
     }
 
-- 
2.20.1



  parent reply index

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-14 17:50 [PATCH v2 00/21] arm: ARMv8.1- and v8.4-PMU, ID reg cleanup, [H]ACTLR2 Peter Maydell
2020-02-14 17:50 ` [PATCH v2 01/21] target/arm: Add _aa32_ to isar_feature functions testing 32-bit ID registers Peter Maydell
2020-02-14 17:50 ` [PATCH v2 02/21] target/arm: Check aa32_pan in take_aarch32_exception(), not aa64_pan Peter Maydell
2020-02-14 20:10   ` Richard Henderson
2020-02-14 17:50 ` Peter Maydell [this message]
2020-02-14 17:50 ` [PATCH v2 04/21] target/arm: Define and use any_predinv isar_feature test Peter Maydell
2020-02-14 17:51 ` [PATCH v2 05/21] target/arm: Factor out PMU register definitions Peter Maydell
2020-02-14 17:51 ` [PATCH v2 06/21] target/arm: Add and use FIELD definitions for ID_AA64DFR0_EL1 Peter Maydell
2020-02-14 17:51 ` [PATCH v2 07/21] target/arm: Use FIELD macros for clearing ID_DFR0 PERFMON field Peter Maydell
2020-02-14 17:51 ` [PATCH v2 08/21] target/arm: Define an aa32_pmu_8_1 isar feature test function Peter Maydell
2020-02-14 17:51 ` [PATCH v2 09/21] target/arm: Add _aa64_ and _any_ versions of pmu_8_1 isar checks Peter Maydell
2020-02-14 17:51 ` [PATCH v2 10/21] target/arm: Stop assuming DBGDIDR always exists Peter Maydell
2020-02-14 20:15   ` Richard Henderson
2020-02-14 17:51 ` [PATCH v2 11/21] target/arm: Move DBGDIDR into ARMISARegisters Peter Maydell
2020-02-14 20:16   ` Richard Henderson
2020-02-14 17:51 ` [PATCH v2 12/21] target/arm: Read debug-related ID registers from KVM Peter Maydell
2020-02-14 20:27   ` Richard Henderson
2020-02-14 17:51 ` [PATCH v2 13/21] target/arm: Implement ARMv8.1-PMU extension Peter Maydell
2020-02-14 17:51 ` [PATCH v2 14/21] target/arm: Implement ARMv8.4-PMU extension Peter Maydell
2020-02-14 17:51 ` [PATCH v2 15/21] target/arm: Provide ARMv8.4-PMU in '-cpu max' Peter Maydell
2020-02-14 17:51 ` [PATCH v2 16/21] target/arm: Correct definition of PMCRDP Peter Maydell
2020-02-14 17:51 ` [PATCH v2 17/21] target/arm: Correct handling of PMCR_EL0.LC bit Peter Maydell
2020-02-14 17:51 ` [PATCH v2 18/21] target/arm: Test correct register in aa32_pan and aa32_ats1e1 checks Peter Maydell
2020-02-14 20:30   ` Richard Henderson
2020-02-14 17:51 ` [PATCH v2 19/21] target/arm: Use isar_feature function for testing AA32HPD feature Peter Maydell
2020-02-14 20:32   ` Richard Henderson
2020-02-14 17:51 ` [PATCH v2 20/21] target/arm: Use FIELD_EX32 for testing 32-bit fields Peter Maydell
2020-02-14 20:32   ` Richard Henderson
2020-02-14 17:51 ` [PATCH v2 21/21] target/arm: Correctly implement ACTLR2, HACTLR2 Peter Maydell
2020-02-14 20:42   ` Richard Henderson

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