In order to avoid interrupt functions to change the FCSR, it needs to be saved
and restored at the beginning and end of the function.
gcc/ChangeLog:
* config/riscv/riscv.cc (riscv_compute_frame_info): Allocate frame for
FCSR.
(riscv_for_each_saved_reg): Save and restore FCSR in interrupt
functions.
* config/riscv/riscv.md (riscv_frcsr): New patterns.
(riscv_fscsr): Likewise.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/interrupt-fcsr-1.c: New test.
* gcc.target/riscv/interrupt-fcsr-2.c: New test.
* gcc.target/riscv/interrupt-fcsr-3.c: New test.
---
gcc/config/riscv/riscv.cc | 48 +++++++++++++++++--
gcc/config/riscv/riscv.md | 13 +++++
.../gcc.target/riscv/interrupt-fcsr-1.c | 15 ++++++
.../gcc.target/riscv/interrupt-fcsr-2.c | 15 ++++++
.../gcc.target/riscv/interrupt-fcsr-3.c | 14 ++++++
5 files changed, 102 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/riscv/interrupt-fcsr-1.c
create mode 100644 gcc/testsuite/gcc.target/riscv/interrupt-fcsr-2.c
create mode 100644 gcc/testsuite/gcc.target/riscv/interrupt-fcsr-3.c
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index dd5361c2bd2..9d71e5c9f72 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -5095,12 +5095,15 @@ riscv_compute_frame_info (void)
frame = &cfun->machine->frame;
- /* In an interrupt function, if we have a large frame, then we need to
- save/restore t0. We check for this before clearing the frame struct. */
+ /* In an interrupt function, there are two cases in which t0 needs to be
used:
+ 1, If we have a large frame, then we need to save/restore t0. We check
for
+ this before clearing the frame struct.
+ 2, Need to save and restore some CSRs in the frame. */
if (cfun->machine->interrupt_handler_p)
{
HOST_WIDE_INT step1 = riscv_first_stack_step (frame, frame->total_size);
- if (! POLY_SMALL_OPERAND_P ((frame->total_size - step1)))
+ if (! POLY_SMALL_OPERAND_P ((frame->total_size - step1))
+ || (TARGET_HARD_FLOAT || TARGET_ZFINX))
interrupt_save_prologue_temp = true;
}
@@ -5147,6 +5150,17 @@ riscv_compute_frame_info (void)
}
}
+ /* In an interrupt function, we need extra space for the initial saves of
CSRs. */
+ if (cfun->machine->interrupt_handler_p
+ && ((TARGET_HARD_FLOAT && frame->fmask)
+ || (TARGET_ZFINX
+ /* Except for RISCV_PROLOGUE_TEMP_REGNUM. */
+ && (frame->mask & ~(1 << RISCV_PROLOGUE_TEMP_REGNUM)))))
+ /* Save and restore FCSR. */
+ /* TODO: When P or V extensions support interrupts, some of their CSRs
+ may also need to be saved and restored. */
+ x_save_size += riscv_stack_align (1 * UNITS_PER_WORD);
+
/* At the bottom of the frame are any outgoing stack arguments. */
offset = riscv_stack_align (crtl->outgoing_args_size);
/* Next are local stack variables. */
@@ -5392,6 +5406,34 @@ riscv_for_each_saved_reg (poly_int64 sp_offset,
riscv_save_restore_fn fn,
}
}
+ /* In an interrupt function, save and restore some necessary CSRs in the
stack
+ to avoid changes in CSRs. */
+ if (regno == RISCV_PROLOGUE_TEMP_REGNUM
+ && cfun->machine->interrupt_handler_p
+ && ((TARGET_HARD_FLOAT && cfun->machine->frame.fmask)
+ || (TARGET_ZFINX
+ && (cfun->machine->frame.mask & ~(1 <<
RISCV_PROLOGUE_TEMP_REGNUM)))))
+ {
+ unsigned int fcsr_size = GET_MODE_SIZE (SImode);
+ if (!epilogue)
+ {
+ riscv_save_restore_reg (word_mode, regno, offset, fn);
+ offset -= fcsr_size;
+ emit_insn (gen_riscv_frcsr (RISCV_PROLOGUE_TEMP (SImode)));
+ riscv_save_restore_reg (SImode, RISCV_PROLOGUE_TEMP_REGNUM,
+ offset, riscv_save_reg);
+ }
+ else
+ {
+ riscv_save_restore_reg (SImode, RISCV_PROLOGUE_TEMP_REGNUM,
+ offset - fcsr_size, riscv_restore_reg);
+ emit_insn (gen_riscv_fscsr (RISCV_PROLOGUE_TEMP (SImode)));
+ riscv_save_restore_reg (word_mode, regno, offset, fn);
+ offset -= fcsr_size;
+ }
+ continue;
+ }
+
riscv_save_restore_reg (word_mode, regno, offset, fn);
}
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index d8e935cb934..565e8cd27cd 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -78,6 +78,8 @@ (define_c_enum "unspecv" [
UNSPECV_GPR_RESTORE
;; Floating-point unspecs.
+ UNSPECV_FRCSR
+ UNSPECV_FSCSR
UNSPECV_FRFLAGS
UNSPECV_FSFLAGS
UNSPECV_FSNVSNAN
@@ -3056,6 +3058,17 @@ (define_insn "gpr_restore_return"
""
"")
+(define_insn "riscv_frcsr"
+ [(set (match_operand:SI 0 "register_operand" "=r")
+ (unspec_volatile [(const_int 0)] UNSPECV_FRCSR))]
+ "TARGET_HARD_FLOAT || TARGET_ZFINX"
+ "frcsr\t%0")
+
+(define_insn "riscv_fscsr"
+ [(unspec_volatile [(match_operand:SI 0 "csr_operand" "rK")] UNSPECV_FSCSR)]
+ "TARGET_HARD_FLOAT || TARGET_ZFINX"
+ "fscsr\t%0")
+
(define_insn "riscv_frflags"
[(set (match_operand:SI 0 "register_operand" "=r")
(unspec_volatile [(const_int 0)] UNSPECV_FRFLAGS))]
diff --git a/gcc/testsuite/gcc.target/riscv/interrupt-fcsr-1.c
b/gcc/testsuite/gcc.target/riscv/interrupt-fcsr-1.c
new file mode 100644
index 00000000000..aaafb08a674
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/interrupt-fcsr-1.c
@@ -0,0 +1,15 @@
+/* Verify that fcsr instructions emitted. */
+/* { dg-do compile } */
+/* { dg-require-effective-target hard_float } */
+/* { dg-options "-O" } */
+
+extern int foo (void);
+
+void __attribute__ ((interrupt))
+sub (void)
+{
+ foo ();
+}
+
+/* { dg-final { scan-assembler-times "frcsr\t" 1 } } */
+/* { dg-final { scan-assembler-times "fscsr\t" 1 } } */
\ No newline at end of file
diff --git a/gcc/testsuite/gcc.target/riscv/interrupt-fcsr-2.c
b/gcc/testsuite/gcc.target/riscv/interrupt-fcsr-2.c
new file mode 100644
index 00000000000..ea22e6a2be4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/interrupt-fcsr-2.c
@@ -0,0 +1,15 @@
+/* Verify that fcsr instructions emitted. */
+/* { dg-do compile } */
+/* { dg-require-effective-target hard_float } */
+/* { dg-options "-O" } */
+
+extern int foo (void);
+extern float interrupt_count;
+void __attribute__ ((interrupt))
+sub (void)
+{
+ interrupt_count++;
+}
+
+/* { dg-final { scan-assembler-times "frcsr\t" 1 } } */
+/* { dg-final { scan-assembler-times "fscsr\t" 1 } } */
diff --git a/gcc/testsuite/gcc.target/riscv/interrupt-fcsr-3.c
b/gcc/testsuite/gcc.target/riscv/interrupt-fcsr-3.c
new file mode 100644
index 00000000000..5e7eac4b770
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/interrupt-fcsr-3.c
@@ -0,0 +1,14 @@
+/* Verify that fcsr instructions are not emitted. */
+/* { dg-do compile } */
+/* { dg-require-effective-target hard_float } */
+/* { dg-options "-O" } */
+
+extern int foo (void);
+
+void __attribute__ ((interrupt))
+sub (void)
+{
+}
+
+/* { dg-final { scan-assembler-not "frcsr\t" } } */
+/* { dg-final { scan-assembler-not "fscsr\t" } } */
--
2.17.1
