[v2,12/28] target/arm: Factor out preserve-fp-state from full_vfp_access_check()

Commit Message

Peter Maydell Nov. 19, 2020, 9:56 p.m. UTC

Factor out the code which handles M-profile lazy FP state preservation
from full_vfp_access_check(); accesses to the FPCXT_NS register are
a special case which need to do just this part (corresponding in the
pseudocode to the PreserveFPState() function), and not the full
set of actions matching the pseudocode ExecuteFPCheck() which
normal FP instructions need to do.

Signed-off-by: Peter Maydell <[e-mail]>
Reviewed-by: Richard Henderson <[e-mail]>
---
 target/arm/translate-vfp.c.inc | 45 ++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 18 deletions(-)

Comments

Philippe Mathieu-Daudé Nov. 19, 2020, 10:18 p.m. UTC | #1

On 11/19/20 10:56 PM, Peter Maydell wrote:
> Factor out the code which handles M-profile lazy FP state preservation
> from full_vfp_access_check(); accesses to the FPCXT_NS register are
> a special case which need to do just this part (corresponding in the
> pseudocode to the PreserveFPState() function), and not the full
> set of actions matching the pseudocode ExecuteFPCheck() which
> normal FP instructions need to do.
> 
> Signed-off-by: Peter Maydell <[e-mail]>
> Reviewed-by: Richard Henderson <[e-mail]>
> ---
>  target/arm/translate-vfp.c.inc | 45 ++++++++++++++++++++--------------
>  1 file changed, 27 insertions(+), 18 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>

Patch

diff --git a/target/arm/translate-vfp.c.inc b/target/arm/translate-vfp.c.inc
index 6bc327e9819..9c90c0647bd 100644
--- a/target/arm/translate-vfp.c.inc
+++ b/target/arm/translate-vfp.c.inc
@@ -83,6 +83,32 @@  static inline long vfp_f16_offset(unsigned reg, bool top)
     return offs;
 }
 
+/*
+ * Generate code for M-profile lazy FP state preservation if needed;
+ * this corresponds to the pseudocode PreserveFPState() function.
+ */
+static void gen_preserve_fp_state(DisasContext *s)
+{
+    if (s->v7m_lspact) {
+        /*
+         * Lazy state saving affects external memory and also the NVIC,
+         * so we must mark it as an IO operation for icount (and cause
+         * this to be the last insn in the TB).
+         */
+        if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
+            s->base.is_jmp = DISAS_UPDATE_EXIT;
+            gen_io_start();
+        }
+        gen_helper_v7m_preserve_fp_state(cpu_env);
+        /*
+         * If the preserve_fp_state helper doesn't throw an exception
+         * then it will clear LSPACT; we don't need to repeat this for
+         * any further FP insns in this TB.
+         */
+        s->v7m_lspact = false;
+    }
+}
+
 /*
  * Check that VFP access is enabled. If it is, do the necessary
  * M-profile lazy-FP handling and then return true.
@@ -113,24 +139,7 @@  static bool full_vfp_access_check(DisasContext *s, bool ignore_vfp_enabled)
         /* Handle M-profile lazy FP state mechanics */
 
         /* Trigger lazy-state preservation if necessary */
-        if (s->v7m_lspact) {
-            /*
-             * Lazy state saving affects external memory and also the NVIC,
-             * so we must mark it as an IO operation for icount (and cause
-             * this to be the last insn in the TB).
-             */
-            if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
-                s->base.is_jmp = DISAS_UPDATE_EXIT;
-                gen_io_start();
-            }
-            gen_helper_v7m_preserve_fp_state(cpu_env);
-            /*
-             * If the preserve_fp_state helper doesn't throw an exception
-             * then it will clear LSPACT; we don't need to repeat this for
-             * any further FP insns in this TB.
-             */
-            s->v7m_lspact = false;
-        }
+        gen_preserve_fp_state(s);
 
         /* Update ownership of FP context: set FPCCR.S to match current state */
         if (s->v8m_fpccr_s_wrong) {