[PATCH] RISC-V: Fix __atomic_compare_exchange with 32 bit value on RV64

[Kito Cheng <kito.cheng@sifive.com>]

atomic_compare_and_swapsi will use lr.w and sc.w to do the atomic operation on
RV64, however lr.w is doing sign extend to DI and compare instruction only have
DI mode on RV64, so the expected value should be sign extend before compare as
well, so that we can get right compare result.

gcc/ChangeLog:

	PR target/114130
	* config/riscv/sync.md (atomic_compare_and_swap<mode>): Sign
	extend the expected value if needed.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/pr114130.c: New.
---
 gcc/config/riscv/sync.md                  |  9 +++++++++
 gcc/testsuite/gcc.target/riscv/pr114130.c | 12 ++++++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/riscv/pr114130.c

diff --git a/gcc/config/riscv/sync.md b/gcc/config/riscv/sync.md
index 54bb0a66518..6f0b5aae08d 100644
--- a/gcc/config/riscv/sync.md
+++ b/gcc/config/riscv/sync.md
@@ -353,6 +353,15 @@
    (match_operand:SI 7 "const_int_operand" "")] ;; mod_f
   "TARGET_ATOMIC"
 {
+  if (word_mode != <MODE>mode && operands[3] != const0_rtx)
+    {
+      /* We don't have SI mode compare on RV64, so we need to make sure expected
+	 value is sign-extended.  */
+      rtx tmp0 = gen_reg_rtx (word_mode);
+      emit_insn (gen_extend_insn (tmp0, operands[3], word_mode, <MODE>mode, 0));
+      operands[3] = simplify_gen_subreg (<MODE>mode, tmp0, word_mode, 0);
+    }
+
   emit_insn (gen_atomic_cas_value_strong<mode> (operands[1], operands[2],
 						operands[3], operands[4],
 						operands[6], operands[7]));
diff --git a/gcc/testsuite/gcc.target/riscv/pr114130.c b/gcc/testsuite/gcc.target/riscv/pr114130.c
new file mode 100644
index 00000000000..647e27dab32
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/pr114130.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gc -mabi=lp64" } */
+#include <stdint-gcc.h>
+
+void foo(uint32_t *p) {
+    uintptr_t x = *(uintptr_t *)p;
+    uint32_t e = !p ? 0 : (uintptr_t)p >> 1;
+    uint32_t d = (uintptr_t)x;
+    __atomic_compare_exchange(p, &e, &d, 0, __ATOMIC_RELAXED, __ATOMIC_RELAXED);
+}
+
+/* { dg-final { scan-assembler-bound {sext.w\t} >= 1 } } */
-- 
2.34.1