[PATCH v2] RISC-V: Fixbug for that XTheadMemPair causes interrupt to fail.

[Jin Ma <jinma@linux.alibaba.com>]

The t0 register is used as a temporary register for interrupts, so it needs
special treatment. It is necessary to avoid using "th.ldd" in the interrupt
program to stop the subsequent operation of the t0 register, so they need to
exchange positions in the function "riscv_for_each_saved_reg".

gcc/ChangeLog:

	* config/riscv/riscv.cc (riscv_for_each_saved_reg): Place the interrupt
	operation before the XTheadMemPair.
---
 gcc/config/riscv/riscv.cc                     | 56 +++++++++----------
 .../riscv/xtheadmempair-interrupt-fcsr.c      | 18 ++++++
 2 files changed, 46 insertions(+), 28 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/riscv/xtheadmempair-interrupt-fcsr.c

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index e25692b86fc..fa2d4d4b779 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -6346,6 +6346,34 @@ riscv_for_each_saved_reg (poly_int64 sp_offset, riscv_save_restore_fn fn,
 	  && riscv_is_eh_return_data_register (regno))
 	continue;
 
+      /* 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;
+	}
+
       if (TARGET_XTHEADMEMPAIR)
 	{
 	  /* Get the next reg/offset pair.  */
@@ -6376,34 +6404,6 @@ 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/testsuite/gcc.target/riscv/xtheadmempair-interrupt-fcsr.c b/gcc/testsuite/gcc.target/riscv/xtheadmempair-interrupt-fcsr.c
new file mode 100644
index 00000000000..d06f05f5c7c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/xtheadmempair-interrupt-fcsr.c
@@ -0,0 +1,18 @@
+/* Verify that fcsr instructions emitted.  */
+/* { dg-do compile } */
+/* { dg-require-effective-target hard_float } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-O1" "-g" "-Oz" "-Os" "-flto" } } */
+/* { dg-options "-march=rv64gc_xtheadmempair -mtune=thead-c906 -funwind-tables" { target { rv64 } } } */
+/* { dg-options "-march=rv32gc_xtheadmempair -mtune=thead-c906 -funwind-tables" { target { rv32 } } } */
+
+
+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 } } */

base-commit: e7f4040d9d6ec40c48ada940168885d7dde03af9
-- 
2.17.1