[RISCV] Add MIPS P8700 processor (#119882)

The P8700 is a high-performance processor from MIPS designed to meet the
demands of modern workloads, offering exceptional scalability and
efficiency. It builds on MIPS's established architectural strengths
while introducing enhancements that set it apart. For more details, you
can check out the official product page here:
https://mips.com/products/hardware/p8700/.

Scheduling model will be added in a separate commit/PR.

Author: djtodoro

clang/test/Driver/riscv-cpus.c

@@ -98,6 +98,23 @@
 // RUN: %clang --target=riscv64 -### -c %s 2>&1 -mtune=rocket-rv64 | FileCheck -check-prefix=MTUNE-ROCKET64 %s
 // MTUNE-ROCKET64: "-tune-cpu" "rocket-rv64"
 
+// RUN: %clang --target=riscv64 -### -c %s 2>&1 -mtune=mips-p8700 | FileCheck -check-prefix=MTUNE-MIPS-P8700 %s
+// MTUNE-MIPS-P8700: "-tune-cpu" "mips-p8700"
+
+// RUN: %clang --target=riscv64 -### -c %s 2>&1 -mcpu=mips-p8700 | FileCheck -check-prefix=MCPU-MIPS-P8700 %s
+// MCPU-MIPS-P8700: "-target-cpu" "mips-p8700"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+m"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+a"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+f"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+d"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+c"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+zicsr"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+zifencei"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+zaamo"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+zalrsc"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+zba"
+// MCPU-MIPS-P8700-SAME: "-target-feature" "+zbb"
+
 // RUN: %clang --target=riscv32 -### -c %s 2>&1 -mtune=syntacore-scr1-base | FileCheck -check-prefix=MTUNE-SYNTACORE-SCR1-BASE %s
 // MTUNE-SYNTACORE-SCR1-BASE: "-tune-cpu" "syntacore-scr1-base"
 

clang/test/Misc/target-invalid-cpu-note/riscv.c

@@ -25,6 +25,7 @@
 // RISCV64: error: unknown target CPU 'not-a-cpu'
 // RISCV64-NEXT: note: valid target CPU values are:
 // RISCV64-SAME: {{^}} generic-rv64
+// RISCV64-SAME: {{^}}, mips-p8700
 // RISCV64-SAME: {{^}}, rocket-rv64
 // RISCV64-SAME: {{^}}, sifive-p450
 // RISCV64-SAME: {{^}}, sifive-p470
@@ -72,6 +73,7 @@
 // TUNE-RISCV64: error: unknown target CPU 'not-a-cpu'
 // TUNE-RISCV64-NEXT: note: valid target CPU values are:
 // TUNE-RISCV64-SAME: {{^}} generic-rv64
+// TUNE-RISCV64-SAME: {{^}}, mips-p8700
 // TUNE-RISCV64-SAME: {{^}}, rocket-rv64
 // TUNE-RISCV64-SAME: {{^}}, sifive-p450
 // TUNE-RISCV64-SAME: {{^}}, sifive-p470

llvm/docs/ReleaseNotes.md

@@ -195,6 +195,7 @@ Changes to the RISC-V Backend
 * Added `Smctr`, `Ssctr` and `Svvptc` extensions.
 * `-mcpu=syntacore-scr7` was added.
 * `-mcpu=tt-ascalon-d8` was added.
+* `-mcpu=mips-p8700` was added.
 * The `Zacas` extension is no longer marked as experimental.
 * Added Smdbltrp, Ssdbltrp extensions to -march.
 * The `Smmpm`, `Smnpm`, `Ssnpm`, `Supm`, and `Sspm` pointer masking extensions

llvm/lib/Target/RISCV/RISCVFeatures.td

@@ -1493,6 +1493,10 @@ def TuneConditionalCompressedMoveFusion
 def HasConditionalMoveFusion : Predicate<"Subtarget->hasConditionalMoveFusion()">;
 def NoConditionalMoveFusion  : Predicate<"!Subtarget->hasConditionalMoveFusion()">;
 
+def TuneMIPSP8700
+    : SubtargetFeature<"mips-p8700", "RISCVProcFamily", "Others",
+                       "MIPS p8700 processor">;
+
 def TuneSiFive7 : SubtargetFeature<"sifive7", "RISCVProcFamily", "SiFive7",
                                    "SiFive 7-Series processors">;
 

llvm/lib/Target/RISCV/RISCVProcessors.td

@@ -95,6 +95,21 @@ def GENERIC_RV64 : RISCVProcessorModel<"generic-rv64",
 // to change to the appropriate rv32/rv64 version.
 def GENERIC : RISCVTuneProcessorModel<"generic", NoSchedModel>, GenericTuneInfo;
 
+def MIPS_P8700 : RISCVProcessorModel<"mips-p8700",
+                                     NoSchedModel,
+                                     [Feature64Bit,
+                                      FeatureStdExtI,
+                                      FeatureStdExtM,
+                                      FeatureStdExtA,
+                                      FeatureStdExtF,
+                                      FeatureStdExtD,
+                                      FeatureStdExtC,
+                                      FeatureStdExtZba,
+                                      FeatureStdExtZbb,
+                                      FeatureStdExtZifencei,
+                                      FeatureStdExtZicsr],
+                                     [TuneMIPSP8700]>;
+
 def ROCKET_RV32 : RISCVProcessorModel<"rocket-rv32",
                                       RocketModel,
                                       [Feature32Bit,