@@ -443,6 +443,10 @@ prologue_saved_reg_p (int regno)
{
gcc_assert (GP_REG_P (regno));
+ /* Do not save the register if function will not return. */
+ if (TREE_THIS_VOLATILE (current_function_decl))
+ return false;
+
if (df_regs_ever_live_p (regno) && !call_used_or_fixed_reg_p (regno))
return true;
new file mode 100644
@@ -0,0 +1,10 @@
+/* Ensure prologues are not generated for noreturn functions. */
+/* { dg-do assemble } */
+/* { dg-options "-Os" } */
+/* { dg-final { object-size text == 0 } } */
+
+void test(void)
+{
+ asm volatile ("# \n\t" : : : "r5", "r10");
+ __builtin_unreachable ();
+}
new file mode 100644
@@ -0,0 +1,11 @@
+/* Ensure prologues are not generated for noreturn functions. */
+/* { dg-do assemble } */
+/* { dg-options "-Os" } */
+/* { dg-final { object-size text == 4 } } */
+
+void test(void)
+{
+ asm volatile ("# \n\t" : : : "r0", "r9");
+ for (;;)
+ ;
+}
There is no need to store callee-saved registers in prologue if the function would never return. Size optimization is paramount for the microcontroller-class PRU. Some backends save some registers for noreturn functions. But for PRU debuggability is a less concern because GDB has not been ported yet for PRU. gcc/ChangeLog: * config/pru/pru.cc (prologue_saved_reg_p): Skip saving if function will not return. gcc/testsuite/ChangeLog: * gcc.target/pru/noreturn-prologue-1.c: New test. * gcc.target/pru/noreturn-prologue-2.c: New test. Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu> --- gcc/config/pru/pru.cc | 4 ++++ gcc/testsuite/gcc.target/pru/noreturn-prologue-1.c | 10 ++++++++++ gcc/testsuite/gcc.target/pru/noreturn-prologue-2.c | 11 +++++++++++ 3 files changed, 25 insertions(+) create mode 100644 gcc/testsuite/gcc.target/pru/noreturn-prologue-1.c create mode 100644 gcc/testsuite/gcc.target/pru/noreturn-prologue-2.c