Hi,
It was discovered that with the attached test case compiled with -O2
-funroll-loops,
the regrename pass renamed one of the registers ($2) to $8 that was not
saved by the prologue.
The attached patch fixes it by defining macro HARD_REGNO_RENAME_OK that returns
zero iff the current function is an interrupt handler and a register was never
live.
Regression is still in progress. Ok to apply if it passes?
Regards,
Robert
gcc/
* config/mips/mips-protos.h (mips_hard_regno_rename_ok): New prototype.
* config/mips/mips.c (mips_hard_regno_rename_ok): New function.
* config/mips/mips.h (HARD_REGNO_RENAME_OK): New.
gcc/testsuite/
* gcc.target/mips/interrupt_handler-bug-1.c: New test.
---
gcc/config/mips/mips-protos.h | 1 +
gcc/config/mips/mips.c | 14 ++++++++++++++
gcc/config/mips/mips.h | 3 +++
gcc/testsuite/gcc.target/mips/interrupt_handler-bug-1.c | 12 ++++++++++++
4 files changed, 30 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/mips/interrupt_handler-bug-1.c
diff --git a/gcc/config/mips/mips-protos.h b/gcc/config/mips/mips-protos.h
index 6ce3d70..e455553 100644
--- a/gcc/config/mips/mips-protos.h
+++ b/gcc/config/mips/mips-protos.h
@@ -317,6 +317,7 @@ extern unsigned int mips_sync_loop_insns (rtx, rtx *);
extern const char *mips_output_division (const char *, rtx *);
extern const char *mips_msa_output_division (const char *, rtx *);
extern const char *mips_output_probe_stack_range (rtx, rtx);
+extern bool mips_hard_regno_rename_ok (unsigned int, unsigned int);
extern unsigned int mips_hard_regno_nregs (int, machine_mode);
extern bool mips_linked_madd_p (rtx, rtx);
extern bool mips_store_data_bypass_p (rtx, rtx);
diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index a9829bd..151f774 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -12959,6 +12959,20 @@ mips_hard_regno_mode_ok_p (unsigned int regno,
machine_mode mode)
return false;
}
+/* Return nonzero if register OLD_REG can be renamed to register NEW_REG. */
+
+bool
+mips_hard_regno_rename_ok (unsigned int old_reg ATTRIBUTE_UNUSED,
+ unsigned int new_reg)
+{
+ /* Interrupt functions can only use registers that have already been
+ saved by the prologue, even if they would normally be call-clobbered. */
+ if (cfun->machine->interrupt_handler_p && !df_regs_ever_live_p (new_reg))
+ return false;
+
+ return true;
+}
+
/* Implement HARD_REGNO_NREGS. */
unsigned int
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index 6578ae5..3fe690a 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -1932,6 +1932,9 @@ struct mips_cpu_info {
#define HARD_REGNO_MODE_OK(REGNO, MODE)
\
mips_hard_regno_mode_ok[ (int)(MODE) ][ (REGNO) ]
+#define HARD_REGNO_RENAME_OK(OLD_REG, NEW_REG) \
+ mips_hard_regno_rename_ok (OLD_REG, NEW_REG)
+
/* Select a register mode required for caller save of hard regno REGNO. */
#define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
mips_hard_regno_caller_save_mode (REGNO, NREGS, MODE)
diff --git a/gcc/testsuite/gcc.target/mips/interrupt_handler-bug-1.c
b/gcc/testsuite/gcc.target/mips/interrupt_handler-bug-1.c
new file mode 100644
index 0000000..877d00c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/interrupt_handler-bug-1.c
@@ -0,0 +1,12 @@
+/* { dg-options "-funroll-loops" } */
+int foo;
+int bar;
+
+void __attribute__ ((interrupt)) isr(void)
+{
+ if (!foo)
+ {
+ while (bar & 0xFF30);
+ }
+}
+/* { dg-final { scan-assembler-not "\\\$8" } } */
--
2.4.5
