We are going to need to generate different code in some cases when
FPCR.AH is 1.  For example:
 * Floating point neg and abs must not flip the sign bit of NaNs
 * some insns (FRECPE, FRECPS, FRECPX, FRSQRTE, FRSQRTS, and various
   BFCVT and BFM bfloat16 ops) need to use a different float_status
   to the usual one

Encode FPCR.AH into the A64 tbflags, so we can refer to it at
translate time.

Because we now have a bit in FPCR that affects codegen, we can't mark
the AArch64 FPCR register as being SUPPRESS_TB_END any more; writes
to it will now end the TB and trigger a regeneration of hflags.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/cpu.h               | 1 +
 target/arm/tcg/translate.h     | 2 ++
 target/arm/helper.c            | 2 +-
 target/arm/tcg/hflags.c        | 4 ++++
 target/arm/tcg/translate-a64.c | 1 +
 5 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 1c91b1f50f2..a71f848cc51 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -3198,6 +3198,7 @@ FIELD(TBFLAG_A64, NV2, 34, 1)
 FIELD(TBFLAG_A64, NV2_MEM_E20, 35, 1)
 /* Set if FEAT_NV2 RAM accesses are big-endian */
 FIELD(TBFLAG_A64, NV2_MEM_BE, 36, 1)
+FIELD(TBFLAG_A64, AH, 37, 1)   /* FPCR.AH */
 
 /*
  * Helpers for using the above. Note that only the A64 accessors use
diff --git a/target/arm/tcg/translate.h b/target/arm/tcg/translate.h
index 084ee63d990..1fc4fdd7794 100644
--- a/target/arm/tcg/translate.h
+++ b/target/arm/tcg/translate.h
@@ -155,6 +155,8 @@ typedef struct DisasContext {
     bool nv2_mem_e20;
     /* True if NV2 enabled and NV2 RAM accesses are big-endian */
     bool nv2_mem_be;
+    /* True if FPCR.AH is 1 (alternate floating point handling) */
+    bool fpcr_ah;
     /*
      * >= 0, a copy of PSTATE.BTYPE, which will be 0 without v8.5-BTI.
      *  < 0, set by the current instruction.
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 40bdfc851a5..7d95eae9971 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -4848,7 +4848,7 @@ static const ARMCPRegInfo v8_cp_reginfo[] = {
       .writefn = aa64_daif_write, .resetfn = arm_cp_reset_ignore },
     { .name = "FPCR", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .opc2 = 0, .crn = 4, .crm = 4,
-      .access = PL0_RW, .type = ARM_CP_FPU | ARM_CP_SUPPRESS_TB_END,
+      .access = PL0_RW, .type = ARM_CP_FPU,
       .readfn = aa64_fpcr_read, .writefn = aa64_fpcr_write },
     { .name = "FPSR", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .opc2 = 1, .crn = 4, .crm = 4,
diff --git a/target/arm/tcg/hflags.c b/target/arm/tcg/hflags.c
index f03977b4b00..b3a78564ec1 100644
--- a/target/arm/tcg/hflags.c
+++ b/target/arm/tcg/hflags.c
@@ -404,6 +404,10 @@ static CPUARMTBFlags rebuild_hflags_a64(CPUARMState *env, int el, int fp_el,
         DP_TBFLAG_A64(flags, TCMA, aa64_va_parameter_tcma(tcr, mmu_idx));
     }
 
+    if (env->vfp.fpcr & FPCR_AH) {
+        DP_TBFLAG_A64(flags, AH, 1);
+    }
+
     return rebuild_hflags_common(env, fp_el, mmu_idx, flags);
 }
 
diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index d6ac2ed418a..be3f4489e5e 100644
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -9655,6 +9655,7 @@ static void aarch64_tr_init_disas_context(DisasContextBase *dcbase,
     dc->nv2 = EX_TBFLAG_A64(tb_flags, NV2);
     dc->nv2_mem_e20 = EX_TBFLAG_A64(tb_flags, NV2_MEM_E20);
     dc->nv2_mem_be = EX_TBFLAG_A64(tb_flags, NV2_MEM_BE);
+    dc->fpcr_ah = EX_TBFLAG_A64(tb_flags, AH);
     dc->vec_len = 0;
     dc->vec_stride = 0;
     dc->cp_regs = arm_cpu->cp_regs;
-- 
2.34.1