Re: [Qemu-devel] [Qemu-arm] [PATCH 12/15] target/arm: Don't calculate lr in arm_v7m_cpu_do_interrupt() until needed

[Philippe Mathieu-Daudé]

On 08/02/2017 01:43 PM, Peter Maydell wrote:

Move the code in arm_v7m_cpu_do_interrupt() that calculates the
magic LR value down to when we're actually going to use it.
Having the calculation and use so far apart makes the code
a little harder to understand than it needs to be.

Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>

Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>

---
  target/arm/helper.c | 15 ++++++++-------
  1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index b64ddb1..0ecc8f1 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6311,13 +6311,6 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)

arm_log_exception(cs->exception_index); - lr = 0xfffffff1;

-    if (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) {
-        lr |= 4;
-    }
-    if (env->v7m.exception == 0)
-        lr |= 8;
-
      /* For exceptions we just mark as pending on the NVIC, and let that
         handle it.  */
      switch (cs->exception_index) {
@@ -6408,6 +6401,14 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
          return; /* Never happens.  Keep compiler happy.  */
      }

+ lr = 0xfffffff1;

+    if (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) {
+        lr |= 4;
+    }
+    if (env->v7m.exception == 0) {
+        lr |= 8;
+    }
+
      v7m_push_stack(cpu);
      v7m_exception_taken(cpu, lr);
      qemu_log_mask(CPU_LOG_INT, "... as %d\n", env->v7m.exception);