target/arm: Don't calculate lr in arm_v7m_cpu_do_interrupt() until needed

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.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1501692241-23310-13-git-send-email-peter.maydell@linaro.org

1 files changed, 8 insertions, 7 deletions

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 941085690b..267a170a79 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6306,13 +6306,6 @@ 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) {
@@ -6403,6 +6396,14 @@ 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);