Please refer "MIPS RV64 P8700/P8700-F Multiprocessing System Programmer’s
Guide" for more info on the extension at
https://mips.com/wp-content/uploads/2025/06/P8700_Programmers_Reference_Manual_Rev1.84_5-31-2025.pdf
lint warnings can be ignored for riscv-ext.opt.
gcc/ChangeLog:
* config/riscv/riscv-ext-mips.def (DEFINE_RISCV_EXT):
Added mips prefetch extension.
* config/riscv/riscv-ext.def: Likewise.
* config/riscv/riscv-ext.opt: Generated file.
* config/riscv/riscv.md (prefetch):.
Added mips prefetch address operand constraint.
* config/riscv/riscv.cc (riscv_prefetch_offset_address_p):
Legitimate address with offset for prefetch check.
* config/riscv/riscv-protos.h: Likewise.
* config/riscv/riscv.h:
Macros to support for mips cached type.
* doc/riscv-ext.texi: Updated for mips prefetch.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/mipsprefetch.c: Test file for mips.pref.
---
gcc/config/riscv/constraints.md | 4 +++
gcc/config/riscv/riscv-ext-mips.def | 13 ++++++++
gcc/config/riscv/riscv-ext.opt | 3 ++
gcc/config/riscv/riscv-protos.h | 2 ++
gcc/config/riscv/riscv.cc | 30 +++++++++++++++++++
gcc/config/riscv/riscv.h | 9 ++++++
gcc/config/riscv/riscv.md | 14 +++++++--
gcc/doc/riscv-ext.texi | 4 +++
gcc/testsuite/gcc.target/riscv/mipsprefetch.c | 28 +++++++++++++++++
9 files changed, 105 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/riscv/mipsprefetch.c
diff --git a/gcc/config/riscv/constraints.md b/gcc/config/riscv/constraints.md
index 5ecaa19eb01..979e0df06f1 100644
--- a/gcc/config/riscv/constraints.md
+++ b/gcc/config/riscv/constraints.md
@@ -330,3 +330,7 @@
(define_constraint "Q"
"An address operand that is valid for a prefetch instruction"
(match_operand 0 "prefetch_operand"))
+
+(define_address_constraint "ZD"
+ "An address operand that is valid for a mips prefetch instruction"
+ (match_test "riscv_prefetch_offset_address_p (op, mode)"))
diff --git a/gcc/config/riscv/riscv-ext-mips.def
b/gcc/config/riscv/riscv-ext-mips.def
index 5d7836d5999..132f6c1060d 100644
--- a/gcc/config/riscv/riscv-ext-mips.def
+++ b/gcc/config/riscv/riscv-ext-mips.def
@@ -33,3 +33,16 @@ DEFINE_RISCV_EXT (
/* BITMASK_GROUP_ID. */ BITMASK_NOT_YET_ALLOCATED,
/* BITMASK_BIT_POSITION. */ BITMASK_NOT_YET_ALLOCATED,
/* EXTRA_EXTENSION_FLAGS. */ 0)
+
+DEFINE_RISCV_EXT (
+ /* NAME. */ xmipscbop,
+ /* UPPERCASE_NAME. */ XMIPSCBOP,
+ /* FULL_NAME. */ "Mips Prefetch extension",
+ /* DESC. */ "",
+ /* URL. */ ,
+ /* DEP_EXTS. */ ({}),
+ /* SUPPORTED_VERSIONS. */ ({{1, 0}}),
+ /* FLAG_GROUP. */ xmips,
+ /* BITMASK_GROUP_ID. */ BITMASK_NOT_YET_ALLOCATED,
+ /* BITMASK_BIT_POSITION. */ BITMASK_NOT_YET_ALLOCATED,
+ /* EXTRA_EXTENSION_FLAGS. */ 0)
diff --git a/gcc/config/riscv/riscv-ext.opt b/gcc/config/riscv/riscv-ext.opt
index 26d6e683acd..11ed64c0ad5 100644
--- a/gcc/config/riscv/riscv-ext.opt
+++ b/gcc/config/riscv/riscv-ext.opt
@@ -449,3 +449,6 @@ Mask(XTHEADVECTOR) Var(riscv_xthead_subext)
Mask(XVENTANACONDOPS) Var(riscv_xventana_subext)
Mask(XMIPSCMOV) Var(riscv_xmips_subext)
+
+Mask(XMIPSCBOP) Var(riscv_xmips_subext)
+
diff --git a/gcc/config/riscv/riscv-protos.h b/gcc/config/riscv/riscv-protos.h
index a41c4c299fa..a193b1f26d3 100644
--- a/gcc/config/riscv/riscv-protos.h
+++ b/gcc/config/riscv/riscv-protos.h
@@ -826,6 +826,8 @@ riscv_process_target_version_attr (tree, location_t);
extern void
riscv_override_options_internal (struct gcc_options *);
extern void riscv_option_override (void);
+extern rtx riscv_prefetch_cookie (rtx, rtx);
+extern bool riscv_prefetch_offset_address_p (rtx, machine_mode);
struct riscv_tune_param;
/* Information about one micro-arch we know about. */
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 1275b034cf8..c420e7a77ab 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -15389,6 +15389,36 @@ synthesize_and (rtx operands[3])
return true;
}
+/* Given that we have an rtx of the form (prefetch ... WRITE LOCALITY),
+ return the first operand of the associated PREF or PREFX insn. */
+rtx
+riscv_prefetch_cookie (rtx write, rtx locality)
+{
+ /* store / load to data cache. */
+ /* locality is unused. */
+ return GEN_INT (INTVAL (write) + DCACHE_HINT + INTVAL (locality) * 0);
+}
+
+/* Return true if X is a legitimate address with offset for prefetch.
+ MODE is the mode of the value being accessed. */
+bool
+riscv_prefetch_offset_address_p (rtx x, machine_mode mode)
+{
+ struct riscv_address_info addr;
+
+ if (riscv_classify_address (&addr, x, mode, false)
+ && addr.type == ADDRESS_REG)
+ {
+ if (TARGET_XMIPSCBOP)
+ return CONST_INT_P (addr.offset)
+ && MIPS_RISCV_9BIT_OFFSET_P (INTVAL (addr.offset));
+ else
+ return addr.offset == const0_rtx;
+ }
+
+ return false;
+}
+
/* Initialize the GCC target structure. */
#undef TARGET_ASM_ALIGNED_HI_OP
diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h
index 45fa521f219..9f0087beb99 100644
--- a/gcc/config/riscv/riscv.h
+++ b/gcc/config/riscv/riscv.h
@@ -1319,4 +1319,13 @@ extern void riscv_remove_unneeded_save_restore_calls
(void);
#define TARGET_HAS_FMV_TARGET_ATTRIBUTE 0
+/* mips pref valid offset range. */
+#define MIPS_RISCV_9BIT_OFFSET_P(OFFSET) (IN_RANGE (OFFSET, 0, 511))
+
+/* mips pref hint cache type. */
+#define ICACHE_HINT (0 << 3)
+#define DCACHE_HINT (1 << 3)
+#define SCACHE_HINT (2 << 3)
+#define TCACHE_HINT (3 << 3)
+
#endif /* ! GCC_RISCV_H */
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index c3b504d0883..5a70e00401e 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -4402,11 +4402,21 @@
)
(define_insn "prefetch"
- [(prefetch (match_operand 0 "prefetch_operand" "Qr")
+ [(prefetch (match_operand 0 "prefetch_operand" "ZD")
(match_operand 1 "imm5_operand" "i")
(match_operand 2 "const_int_operand" "n"))]
- "TARGET_ZICBOP"
+ "TARGET_ZICBOP || TARGET_XMIPSCBOP"
{
+ if (TARGET_XMIPSCBOP)
+ {
+ /* Mips Prefetch write is nop for p8700. */
+ if (operands[1] != CONST0_RTX (GET_MODE (operands[1])))
+ return "nop";
+
+ operands[1] = riscv_prefetch_cookie (operands[1], operands[2]);
+ return "mips.pref\t%1,%a0";
+ }
+
switch (INTVAL (operands[1]))
{
case 0:
diff --git a/gcc/doc/riscv-ext.texi b/gcc/doc/riscv-ext.texi
index 572b70e20fa..185084edde7 100644
--- a/gcc/doc/riscv-ext.texi
+++ b/gcc/doc/riscv-ext.texi
@@ -718,4 +718,8 @@
@tab 1.0
@tab Mips conditional move extension
+@item xmipscbop
+@tab 1.0
+@tab Mips Prefetch extension
+
@end multitable
diff --git a/gcc/testsuite/gcc.target/riscv/mipsprefetch.c
b/gcc/testsuite/gcc.target/riscv/mipsprefetch.c
new file mode 100644
index 00000000000..2dbdb44b653
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/mipsprefetch.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32imafd_xmipscbop" { target { rv32 } } } */
+/* { dg-options "-march=rv64imafd_xmipscbop -mabi=lp64d" { target { rv64 } } }
*/
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" } } */
+
+
+void prefetch_read(char *a)
+{
+ __builtin_prefetch (&a[0], 0, 0);
+}
+
+void prefetch_write(char *a)
+{
+ __builtin_prefetch (&a[1], 1, 0);
+}
+
+void prefetch_read_within_range_offset(char *a)
+{
+ __builtin_prefetch (&a[511], 0, 1);
+}
+
+void prefetch_write_out_range_offset(char *a)
+{
+ __builtin_prefetch (&a[512], 1, 1);
+}
+
+/* { dg-final { scan-assembler-times "mips.pref" 2 } } */
+
--
2.43.0
