target/arm: Replace A64 get_fpstatus_ptr() with generic fpstatus_ptr()

We currently have two versions of get_fpstatus_ptr(), which both take
an effectively boolean argument:
 * the one for A64 takes "bool is_f16" to distinguish fp16 from other ops
 * the one for A32/T32 takes "int neon" to distinguish Neon from other ops

This is confusing, and to implement ARMv8.2-FP16 the A32/T32 one will
need to make a four-way distinction between "non-Neon, FP16",
"non-Neon, single/double", "Neon, FP16" and "Neon, single/double".
The A64 version will then be a strict subset of the A32/T32 version.

To clean this all up, we want to go to a single implementation which
takes an enum argument with values FPST_FPCR, FPST_STD,
FPST_FPCR_F16, and FPST_STD_F16.  We rename the function to
fpstatus_ptr() so that unconverted code gets a compilation error
rather than silently passing the wrong thing to the new function.

This commit implements that new API, and converts A64 to use it:
 get_fpstatus_ptr(false) -> fpstatus_ptr(FPST_FPCR)
 get_fpstatus_ptr(true) -> fpstatus_ptr(FPST_FPCR_F16)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20200806104453.30393-2-peter.maydell@linaro.org

1 files changed, 51 insertions, 0 deletions

diff --git a/target/arm/translate.h b/target/arm/translate.h
index 16f2699ad7..e3680e6547 100644
--- a/target/arm/translate.h
+++ b/target/arm/translate.h
@@ -393,4 +393,55 @@ typedef void CryptoThreeOpIntFn(TCGv_ptr, TCGv_ptr, TCGv_i32);
 typedef void CryptoThreeOpFn(TCGv_ptr, TCGv_ptr, TCGv_ptr);
 typedef void AtomicThreeOpFn(TCGv_i64, TCGv_i64, TCGv_i64, TCGArg, MemOp);
 
+/*
+ * Enum for argument to fpstatus_ptr().
+ */
+typedef enum ARMFPStatusFlavour {
+    FPST_FPCR,
+    FPST_FPCR_F16,
+    FPST_STD,
+    FPST_STD_F16,
+} ARMFPStatusFlavour;
+
+/**
+ * fpstatus_ptr: return TCGv_ptr to the specified fp_status field
+ *
+ * We have multiple softfloat float_status fields in the Arm CPU state struct
+ * (see the comment in cpu.h for details). Return a TCGv_ptr which has
+ * been set up to point to the requested field in the CPU state struct.
+ * The options are:
+ *
+ * FPST_FPCR
+ *   for non-FP16 operations controlled by the FPCR
+ * FPST_FPCR_F16
+ *   for operations controlled by the FPCR where FPCR.FZ16 is to be used
+ * FPST_STD
+ *   for A32/T32 Neon operations using the "standard FPSCR value"
+ * FPST_STD_F16
+ *   as FPST_STD, but where FPCR.FZ16 is to be used
+ */
+static inline TCGv_ptr fpstatus_ptr(ARMFPStatusFlavour flavour)
+{
+    TCGv_ptr statusptr = tcg_temp_new_ptr();
+    int offset;
+
+    switch (flavour) {
+    case FPST_FPCR:
+        offset = offsetof(CPUARMState, vfp.fp_status);
+        break;
+    case FPST_FPCR_F16:
+        offset = offsetof(CPUARMState, vfp.fp_status_f16);
+        break;
+    case FPST_STD:
+        offset = offsetof(CPUARMState, vfp.standard_fp_status);
+        break;
+    case FPST_STD_F16:
+        /* Not yet used or implemented: fall through to assert */
+    default:
+        g_assert_not_reached();
+    }
+    tcg_gen_addi_ptr(statusptr, cpu_env, offset);
+    return statusptr;
+}
+
 #endif /* TARGET_ARM_TRANSLATE_H */