[llvm] [RISCV] Support PreserveMost calling convention (PR #148214)

Pengcheng Wang via llvm-commits llvm-commits at lists.llvm.org
Tue Jul 29 22:55:50 PDT 2025


https://github.com/wangpc-pp updated https://github.com/llvm/llvm-project/pull/148214

>From 7965e1e17971e81c4ad99160f1adbc8e49571de1 Mon Sep 17 00:00:00 2001
From: Pengcheng Wang <wangpengcheng.pp at bytedance.com>
Date: Fri, 11 Jul 2025 18:55:49 +0800
Subject: [PATCH 1/7] [RISCV] Support PreserveMost calling convention

This adds the simplest implementation of `PreserveMost` calling
convention and we preserve `x5-x31` registers.

Fixes #148147.
---
 llvm/docs/LangRef.rst                         |   2 +
 llvm/lib/Target/RISCV/RISCVCallingConv.td     |   2 +
 llvm/lib/Target/RISCV/RISCVISelLowering.cpp   |   1 +
 llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp   |   2 +
 .../RISCV/calling-conv-preserve-most.ll       | 165 ++++++++++++++++++
 5 files changed, 172 insertions(+)
 create mode 100644 llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll

diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index eb2ef6bc35742..c838d96a0fa03 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -413,6 +413,8 @@ added in the future:
     - On AArch64 the callee preserves all general purpose registers, except
       X0-X8 and X16-X18. Not allowed with ``nest``.
 
+    - On RISC-V the callee preserve x5-x31 registers.
+
     The idea behind this convention is to support calls to runtime functions
     that have a hot path and a cold path. The hot path is usually a small piece
     of code that doesn't use many registers. The cold path might need to call out to
diff --git a/llvm/lib/Target/RISCV/RISCVCallingConv.td b/llvm/lib/Target/RISCV/RISCVCallingConv.td
index 4c303a93c7349..bb2e93906a1e5 100644
--- a/llvm/lib/Target/RISCV/RISCVCallingConv.td
+++ b/llvm/lib/Target/RISCV/RISCVCallingConv.td
@@ -95,3 +95,5 @@ def CSR_XLEN_F32_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F32_V_Interrupt,
 // Same as CSR_XLEN_F64_V_Interrupt, but excluding X16-X31.
 def CSR_XLEN_F64_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F64_V_Interrupt,
                                                    (sequence "X%u", 16, 31))>;
+
+def CSR_RT_MostRegs : CalleeSavedRegs<(add (sequence "X%u", 5, 31))>;
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index dbe992208c9f3..a2ecd1c276165 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -22476,6 +22476,7 @@ SDValue RISCVTargetLowering::LowerFormalArguments(
   case CallingConv::C:
   case CallingConv::Fast:
   case CallingConv::SPIR_KERNEL:
+  case CallingConv::PreserveMost:
   case CallingConv::GRAAL:
   case CallingConv::RISCV_VectorCall:
 #define CC_VLS_CASE(ABI_VLEN) case CallingConv::RISCV_VLSCall_##ABI_VLEN:
diff --git a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
index 540412366026b..44c7ca3587cc1 100644
--- a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
@@ -68,6 +68,8 @@ RISCVRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
   auto &Subtarget = MF->getSubtarget<RISCVSubtarget>();
   if (MF->getFunction().getCallingConv() == CallingConv::GHC)
     return CSR_NoRegs_SaveList;
+  if (MF->getFunction().getCallingConv() == CallingConv::PreserveMost)
+    return CSR_RT_MostRegs_SaveList;
   if (MF->getFunction().hasFnAttribute("interrupt")) {
     if (Subtarget.hasVInstructions()) {
       if (Subtarget.hasStdExtD())
diff --git a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
new file mode 100644
index 0000000000000..a0345363601a5
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
@@ -0,0 +1,165 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 < %s | FileCheck %s -check-prefix=RV32
+; RUN: llc -mtriple=riscv64 < %s | FileCheck %s -check-prefix=RV64
+
+; Check the PreserveMost calling convention works.
+
+declare void @standard_cc_func()
+declare preserve_mostcc void @preserve_mostcc_func()
+
+define preserve_mostcc void @preserve_mostcc1() nounwind {
+; RV32-LABEL: preserve_mostcc1:
+; RV32:       # %bb.0: # %entry
+; RV32-NEXT:    addi sp, sp, -64
+; RV32-NEXT:    sw t0, 60(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t1, 56(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t2, 52(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a0, 48(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a1, 44(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a2, 40(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a3, 36(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a4, 32(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a5, 28(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a6, 24(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a7, 20(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t3, 16(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t4, 12(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t5, 8(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t6, 4(sp) # 4-byte Folded Spill
+; RV32-NEXT:    call standard_cc_func
+; RV32-NEXT:    lw t0, 60(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t1, 56(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t2, 52(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a0, 48(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a1, 44(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a2, 40(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a3, 36(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a4, 32(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a5, 28(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a6, 24(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a7, 20(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t3, 16(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t4, 12(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t5, 8(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t6, 4(sp) # 4-byte Folded Reload
+; RV32-NEXT:    addi sp, sp, 64
+; RV32-NEXT:    ret
+;
+; RV64-LABEL: preserve_mostcc1:
+; RV64:       # %bb.0: # %entry
+; RV64-NEXT:    addi sp, sp, -128
+; RV64-NEXT:    sd t0, 120(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t1, 112(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t2, 104(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a0, 96(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a1, 88(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a2, 80(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a3, 72(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a4, 64(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a5, 56(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a6, 48(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a7, 40(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t3, 32(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t4, 24(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t5, 16(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t6, 8(sp) # 8-byte Folded Spill
+; RV64-NEXT:    call standard_cc_func
+; RV64-NEXT:    ld t0, 120(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t1, 112(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t2, 104(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a0, 96(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a1, 88(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a2, 80(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a3, 72(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a4, 64(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a5, 56(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a6, 48(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a7, 40(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t3, 32(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t4, 24(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t5, 16(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t6, 8(sp) # 8-byte Folded Reload
+; RV64-NEXT:    addi sp, sp, 128
+; RV64-NEXT:    ret
+entry:
+  call void @standard_cc_func()
+  ret void
+}
+
+define preserve_mostcc void @preserve_mostcc2() nounwind {
+; RV32-LABEL: preserve_mostcc2:
+; RV32:       # %bb.0:
+; RV32-NEXT:    addi sp, sp, -64
+; RV32-NEXT:    sw t0, 60(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t1, 56(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t2, 52(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a0, 48(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a1, 44(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a2, 40(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a3, 36(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a4, 32(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a5, 28(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a6, 24(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a7, 20(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t3, 16(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t4, 12(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t5, 8(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t6, 4(sp) # 4-byte Folded Spill
+; RV32-NEXT:    call preserve_mostcc_func
+; RV32-NEXT:    lw t0, 60(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t1, 56(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t2, 52(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a0, 48(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a1, 44(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a2, 40(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a3, 36(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a4, 32(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a5, 28(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a6, 24(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a7, 20(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t3, 16(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t4, 12(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t5, 8(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t6, 4(sp) # 4-byte Folded Reload
+; RV32-NEXT:    addi sp, sp, 64
+; RV32-NEXT:    ret
+;
+; RV64-LABEL: preserve_mostcc2:
+; RV64:       # %bb.0:
+; RV64-NEXT:    addi sp, sp, -128
+; RV64-NEXT:    sd t0, 120(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t1, 112(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t2, 104(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a0, 96(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a1, 88(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a2, 80(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a3, 72(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a4, 64(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a5, 56(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a6, 48(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a7, 40(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t3, 32(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t4, 24(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t5, 16(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t6, 8(sp) # 8-byte Folded Spill
+; RV64-NEXT:    call preserve_mostcc_func
+; RV64-NEXT:    ld t0, 120(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t1, 112(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t2, 104(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a0, 96(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a1, 88(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a2, 80(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a3, 72(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a4, 64(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a5, 56(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a6, 48(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a7, 40(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t3, 32(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t4, 24(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t5, 16(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t6, 8(sp) # 8-byte Folded Reload
+; RV64-NEXT:    addi sp, sp, 128
+; RV64-NEXT:    ret
+  call preserve_mostcc void @preserve_mostcc_func()
+  ret void
+}

>From 901dbe4e2400edd6d8c4a0e26382210d9ae7c024 Mon Sep 17 00:00:00 2001
From: Pengcheng Wang <wangpengcheng.pp at bytedance.com>
Date: Tue, 15 Jul 2025 11:46:48 +0800
Subject: [PATCH 2/7] Add E and getCallPreservedMask

---
 llvm/lib/Target/RISCV/RISCVCallingConv.td     |   4 +-
 llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp   |  12 +-
 .../RISCV/calling-conv-preserve-most.ll       | 314 ++++++++++--------
 3 files changed, 181 insertions(+), 149 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVCallingConv.td b/llvm/lib/Target/RISCV/RISCVCallingConv.td
index bb2e93906a1e5..ef3501a228e2a 100644
--- a/llvm/lib/Target/RISCV/RISCVCallingConv.td
+++ b/llvm/lib/Target/RISCV/RISCVCallingConv.td
@@ -96,4 +96,6 @@ def CSR_XLEN_F32_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F32_V_Interrupt,
 def CSR_XLEN_F64_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F64_V_Interrupt,
                                                    (sequence "X%u", 16, 31))>;
 
-def CSR_RT_MostRegs : CalleeSavedRegs<(add (sequence "X%u", 5, 31))>;
+def CSR_RT_MostRegs : CalleeSavedRegs<(add X1, (sequence "X%u", 5, 31))>;
+def CSR_RT_MostRegs_RVE : CalleeSavedRegs<(sub CSR_RT_MostRegs,
+                                               (sequence "X%u", 16, 31))>;
diff --git a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
index 44c7ca3587cc1..816fd95a55ed0 100644
--- a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "RISCVRegisterInfo.h"
+#include "MCTargetDesc/RISCVBaseInfo.h"
 #include "RISCV.h"
 #include "RISCVSubtarget.h"
 #include "llvm/ADT/SmallSet.h"
@@ -69,7 +70,8 @@ RISCVRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
   if (MF->getFunction().getCallingConv() == CallingConv::GHC)
     return CSR_NoRegs_SaveList;
   if (MF->getFunction().getCallingConv() == CallingConv::PreserveMost)
-    return CSR_RT_MostRegs_SaveList;
+    return Subtarget.hasStdExtE() ? CSR_RT_MostRegs_RVE_SaveList
+                                  : CSR_RT_MostRegs_SaveList;
   if (MF->getFunction().hasFnAttribute("interrupt")) {
     if (Subtarget.hasVInstructions()) {
       if (Subtarget.hasStdExtD())
@@ -813,7 +815,13 @@ RISCVRegisterInfo::getCallPreservedMask(const MachineFunction & MF,
 
   if (CC == CallingConv::GHC)
     return CSR_NoRegs_RegMask;
-  switch (Subtarget.getTargetABI()) {
+  RISCVABI::ABI ABI = Subtarget.getTargetABI();
+  if (CC == CallingConv::PreserveMost) {
+    if (ABI == RISCVABI::ABI_ILP32E || ABI == RISCVABI::ABI_LP64E)
+      return CSR_RT_MostRegs_RVE_RegMask;
+    return CSR_RT_MostRegs_RegMask;
+  }
+  switch (ABI) {
   default:
     llvm_unreachable("Unrecognized ABI");
   case RISCVABI::ABI_ILP32E:
diff --git a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
index a0345363601a5..dd8ef7ac55892 100644
--- a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
+++ b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
@@ -1,6 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 < %s | FileCheck %s -check-prefix=RV32
-; RUN: llc -mtriple=riscv64 < %s | FileCheck %s -check-prefix=RV64
+; RUN: llc -mtriple=riscv32 < %s | FileCheck %s -check-prefix=RV32I
+; RUN: llc -mtriple=riscv64 < %s | FileCheck %s -check-prefix=RV64I
+; RUN: llc -mtriple=riscv32 -mattr=+e -target-abi ilp32e < %s | FileCheck %s -check-prefix=RV32E
+; RUN: llc -mtriple=riscv64 -mattr=+e -target-abi lp64e < %s | FileCheck %s -check-prefix=RV64E
 
 ; Check the PreserveMost calling convention works.
 
@@ -8,158 +10,178 @@ declare void @standard_cc_func()
 declare preserve_mostcc void @preserve_mostcc_func()
 
 define preserve_mostcc void @preserve_mostcc1() nounwind {
-; RV32-LABEL: preserve_mostcc1:
-; RV32:       # %bb.0: # %entry
-; RV32-NEXT:    addi sp, sp, -64
-; RV32-NEXT:    sw t0, 60(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t1, 56(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t2, 52(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a0, 48(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a1, 44(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a2, 40(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a3, 36(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a4, 32(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a5, 28(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a6, 24(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a7, 20(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t3, 16(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t4, 12(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t5, 8(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t6, 4(sp) # 4-byte Folded Spill
-; RV32-NEXT:    call standard_cc_func
-; RV32-NEXT:    lw t0, 60(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t1, 56(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t2, 52(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a0, 48(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a1, 44(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a2, 40(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a3, 36(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a4, 32(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a5, 28(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a6, 24(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a7, 20(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t3, 16(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t4, 12(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t5, 8(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t6, 4(sp) # 4-byte Folded Reload
-; RV32-NEXT:    addi sp, sp, 64
-; RV32-NEXT:    ret
+; RV32I-LABEL: preserve_mostcc1:
+; RV32I:       # %bb.0: # %entry
+; RV32I-NEXT:    addi sp, sp, -64
+; RV32I-NEXT:    sw ra, 60(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t0, 56(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t1, 52(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t2, 48(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a0, 44(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a1, 40(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a2, 36(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a3, 32(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a4, 28(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a5, 24(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a6, 20(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a7, 16(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t3, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t4, 8(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t5, 4(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t6, 0(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    call standard_cc_func
+; RV32I-NEXT:    lw ra, 60(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t0, 56(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t1, 52(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t2, 48(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a0, 44(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a1, 40(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a2, 36(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a3, 32(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a4, 28(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a5, 24(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a6, 20(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a7, 16(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t3, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t4, 8(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t5, 4(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t6, 0(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 64
+; RV32I-NEXT:    ret
 ;
-; RV64-LABEL: preserve_mostcc1:
-; RV64:       # %bb.0: # %entry
-; RV64-NEXT:    addi sp, sp, -128
-; RV64-NEXT:    sd t0, 120(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t1, 112(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t2, 104(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a0, 96(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a1, 88(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a2, 80(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a3, 72(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a4, 64(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a5, 56(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a6, 48(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a7, 40(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t3, 32(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t4, 24(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t5, 16(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t6, 8(sp) # 8-byte Folded Spill
-; RV64-NEXT:    call standard_cc_func
-; RV64-NEXT:    ld t0, 120(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t1, 112(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t2, 104(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a0, 96(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a1, 88(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a2, 80(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a3, 72(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a4, 64(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a5, 56(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a6, 48(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a7, 40(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t3, 32(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t4, 24(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t5, 16(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t6, 8(sp) # 8-byte Folded Reload
-; RV64-NEXT:    addi sp, sp, 128
-; RV64-NEXT:    ret
+; RV64I-LABEL: preserve_mostcc1:
+; RV64I:       # %bb.0: # %entry
+; RV64I-NEXT:    addi sp, sp, -128
+; RV64I-NEXT:    sd ra, 120(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t0, 112(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t1, 104(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t2, 96(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a0, 88(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a1, 80(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a2, 72(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a3, 64(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a4, 56(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a5, 48(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a6, 40(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a7, 32(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t3, 24(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t4, 16(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t5, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t6, 0(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    call standard_cc_func
+; RV64I-NEXT:    ld ra, 120(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t0, 112(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t1, 104(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t2, 96(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a0, 88(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a1, 80(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a2, 72(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a3, 64(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a4, 56(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a5, 48(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a6, 40(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a7, 32(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t3, 24(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t4, 16(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t5, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t6, 0(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 128
+; RV64I-NEXT:    ret
+;
+; RV32E-LABEL: preserve_mostcc1:
+; RV32E:       # %bb.0: # %entry
+; RV32E-NEXT:    addi sp, sp, -40
+; RV32E-NEXT:    sw ra, 36(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw t0, 32(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw t1, 28(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw t2, 24(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw a0, 20(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw a1, 16(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw a2, 12(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw a3, 8(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw a4, 4(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw a5, 0(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    call standard_cc_func
+; RV32E-NEXT:    lw ra, 36(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw t0, 32(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw t1, 28(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw t2, 24(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw a0, 20(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw a1, 16(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw a2, 12(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw a3, 8(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw a4, 4(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw a5, 0(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    addi sp, sp, 40
+; RV32E-NEXT:    ret
+;
+; RV64E-LABEL: preserve_mostcc1:
+; RV64E:       # %bb.0: # %entry
+; RV64E-NEXT:    addi sp, sp, -80
+; RV64E-NEXT:    sd ra, 72(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd t0, 64(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd t1, 56(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd t2, 48(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd a0, 40(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd a1, 32(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd a2, 24(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd a3, 16(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd a4, 8(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd a5, 0(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    call standard_cc_func
+; RV64E-NEXT:    ld ra, 72(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld t0, 64(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld t1, 56(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld t2, 48(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld a0, 40(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld a1, 32(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld a2, 24(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld a3, 16(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld a4, 8(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld a5, 0(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    addi sp, sp, 80
+; RV64E-NEXT:    ret
 entry:
   call void @standard_cc_func()
   ret void
 }
 
 define preserve_mostcc void @preserve_mostcc2() nounwind {
-; RV32-LABEL: preserve_mostcc2:
-; RV32:       # %bb.0:
-; RV32-NEXT:    addi sp, sp, -64
-; RV32-NEXT:    sw t0, 60(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t1, 56(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t2, 52(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a0, 48(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a1, 44(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a2, 40(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a3, 36(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a4, 32(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a5, 28(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a6, 24(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw a7, 20(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t3, 16(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t4, 12(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t5, 8(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw t6, 4(sp) # 4-byte Folded Spill
-; RV32-NEXT:    call preserve_mostcc_func
-; RV32-NEXT:    lw t0, 60(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t1, 56(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t2, 52(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a0, 48(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a1, 44(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a2, 40(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a3, 36(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a4, 32(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a5, 28(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a6, 24(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw a7, 20(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t3, 16(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t4, 12(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t5, 8(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw t6, 4(sp) # 4-byte Folded Reload
-; RV32-NEXT:    addi sp, sp, 64
-; RV32-NEXT:    ret
+; RV32I-LABEL: preserve_mostcc2:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -16
+; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    call preserve_mostcc_func
+; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 16
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: preserve_mostcc2:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -16
+; RV64I-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    call preserve_mostcc_func
+; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 16
+; RV64I-NEXT:    ret
+;
+; RV32E-LABEL: preserve_mostcc2:
+; RV32E:       # %bb.0:
+; RV32E-NEXT:    addi sp, sp, -4
+; RV32E-NEXT:    sw ra, 0(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    call preserve_mostcc_func
+; RV32E-NEXT:    lw ra, 0(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    addi sp, sp, 4
+; RV32E-NEXT:    ret
 ;
-; RV64-LABEL: preserve_mostcc2:
-; RV64:       # %bb.0:
-; RV64-NEXT:    addi sp, sp, -128
-; RV64-NEXT:    sd t0, 120(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t1, 112(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t2, 104(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a0, 96(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a1, 88(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a2, 80(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a3, 72(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a4, 64(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a5, 56(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a6, 48(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd a7, 40(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t3, 32(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t4, 24(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t5, 16(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd t6, 8(sp) # 8-byte Folded Spill
-; RV64-NEXT:    call preserve_mostcc_func
-; RV64-NEXT:    ld t0, 120(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t1, 112(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t2, 104(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a0, 96(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a1, 88(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a2, 80(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a3, 72(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a4, 64(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a5, 56(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a6, 48(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld a7, 40(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t3, 32(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t4, 24(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t5, 16(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld t6, 8(sp) # 8-byte Folded Reload
-; RV64-NEXT:    addi sp, sp, 128
-; RV64-NEXT:    ret
+; RV64E-LABEL: preserve_mostcc2:
+; RV64E:       # %bb.0:
+; RV64E-NEXT:    addi sp, sp, -8
+; RV64E-NEXT:    sd ra, 0(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    call preserve_mostcc_func
+; RV64E-NEXT:    ld ra, 0(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    addi sp, sp, 8
+; RV64E-NEXT:    ret
   call preserve_mostcc void @preserve_mostcc_func()
   ret void
 }

>From 1b545dc25e58ae558ae72d4ace170997c7f30408 Mon Sep 17 00:00:00 2001
From: Pengcheng Wang <wangpengcheng.pp at bytedance.com>
Date: Mon, 28 Jul 2025 11:19:42 +0800
Subject: [PATCH 3/7] Update CSR list to exclude t1, t2 and t3

---
 llvm/lib/Target/RISCV/RISCVCallingConv.td     |   2 +-
 .../RISCV/calling-conv-preserve-most.ll       | 112 +++++++-----------
 2 files changed, 47 insertions(+), 67 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVCallingConv.td b/llvm/lib/Target/RISCV/RISCVCallingConv.td
index ef3501a228e2a..da6b95da12160 100644
--- a/llvm/lib/Target/RISCV/RISCVCallingConv.td
+++ b/llvm/lib/Target/RISCV/RISCVCallingConv.td
@@ -96,6 +96,6 @@ def CSR_XLEN_F32_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F32_V_Interrupt,
 def CSR_XLEN_F64_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F64_V_Interrupt,
                                                    (sequence "X%u", 16, 31))>;
 
-def CSR_RT_MostRegs : CalleeSavedRegs<(add X1, (sequence "X%u", 5, 31))>;
+def CSR_RT_MostRegs : CalleeSavedRegs<(sub CSR_Interrupt, X6, X7, X28)>;
 def CSR_RT_MostRegs_RVE : CalleeSavedRegs<(sub CSR_RT_MostRegs,
                                                (sequence "X%u", 16, 31))>;
diff --git a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
index dd8ef7ac55892..2fe2108679570 100644
--- a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
+++ b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
@@ -15,47 +15,39 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV32I-NEXT:    addi sp, sp, -64
 ; RV32I-NEXT:    sw ra, 60(sp) # 4-byte Folded Spill
 ; RV32I-NEXT:    sw t0, 56(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t1, 52(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t2, 48(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a0, 44(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a1, 40(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a2, 36(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a3, 32(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a4, 28(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a5, 24(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a6, 20(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a7, 16(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t3, 12(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t4, 8(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t5, 4(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t6, 0(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a0, 52(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a1, 48(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a2, 44(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a3, 40(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a4, 36(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a5, 32(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a6, 28(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a7, 24(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t4, 20(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t5, 16(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t6, 12(sp) # 4-byte Folded Spill
 ; RV32I-NEXT:    call standard_cc_func
 ; RV32I-NEXT:    lw ra, 60(sp) # 4-byte Folded Reload
 ; RV32I-NEXT:    lw t0, 56(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t1, 52(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t2, 48(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a0, 44(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a1, 40(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a2, 36(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a3, 32(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a4, 28(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a5, 24(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a6, 20(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a7, 16(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t3, 12(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t4, 8(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t5, 4(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t6, 0(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a0, 52(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a1, 48(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a2, 44(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a3, 40(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a4, 36(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a5, 32(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a6, 28(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a7, 24(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t4, 20(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t5, 16(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t6, 12(sp) # 4-byte Folded Reload
 ; RV32I-NEXT:    addi sp, sp, 64
 ; RV32I-NEXT:    ret
 ;
 ; RV64I-LABEL: preserve_mostcc1:
 ; RV64I:       # %bb.0: # %entry
-; RV64I-NEXT:    addi sp, sp, -128
-; RV64I-NEXT:    sd ra, 120(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t0, 112(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t1, 104(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t2, 96(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    addi sp, sp, -112
+; RV64I-NEXT:    sd ra, 104(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t0, 96(sp) # 8-byte Folded Spill
 ; RV64I-NEXT:    sd a0, 88(sp) # 8-byte Folded Spill
 ; RV64I-NEXT:    sd a1, 80(sp) # 8-byte Folded Spill
 ; RV64I-NEXT:    sd a2, 72(sp) # 8-byte Folded Spill
@@ -64,15 +56,12 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV64I-NEXT:    sd a5, 48(sp) # 8-byte Folded Spill
 ; RV64I-NEXT:    sd a6, 40(sp) # 8-byte Folded Spill
 ; RV64I-NEXT:    sd a7, 32(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t3, 24(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t4, 16(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t5, 8(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t6, 0(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t4, 24(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t5, 16(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t6, 8(sp) # 8-byte Folded Spill
 ; RV64I-NEXT:    call standard_cc_func
-; RV64I-NEXT:    ld ra, 120(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t0, 112(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t1, 104(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t2, 96(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld ra, 104(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t0, 96(sp) # 8-byte Folded Reload
 ; RV64I-NEXT:    ld a0, 88(sp) # 8-byte Folded Reload
 ; RV64I-NEXT:    ld a1, 80(sp) # 8-byte Folded Reload
 ; RV64I-NEXT:    ld a2, 72(sp) # 8-byte Folded Reload
@@ -81,20 +70,17 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV64I-NEXT:    ld a5, 48(sp) # 8-byte Folded Reload
 ; RV64I-NEXT:    ld a6, 40(sp) # 8-byte Folded Reload
 ; RV64I-NEXT:    ld a7, 32(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t3, 24(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t4, 16(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t5, 8(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t6, 0(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    addi sp, sp, 128
+; RV64I-NEXT:    ld t4, 24(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t5, 16(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t6, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 112
 ; RV64I-NEXT:    ret
 ;
 ; RV32E-LABEL: preserve_mostcc1:
 ; RV32E:       # %bb.0: # %entry
-; RV32E-NEXT:    addi sp, sp, -40
-; RV32E-NEXT:    sw ra, 36(sp) # 4-byte Folded Spill
-; RV32E-NEXT:    sw t0, 32(sp) # 4-byte Folded Spill
-; RV32E-NEXT:    sw t1, 28(sp) # 4-byte Folded Spill
-; RV32E-NEXT:    sw t2, 24(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    addi sp, sp, -32
+; RV32E-NEXT:    sw ra, 28(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw t0, 24(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw a0, 20(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw a1, 16(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw a2, 12(sp) # 4-byte Folded Spill
@@ -102,26 +88,22 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV32E-NEXT:    sw a4, 4(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw a5, 0(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    call standard_cc_func
-; RV32E-NEXT:    lw ra, 36(sp) # 4-byte Folded Reload
-; RV32E-NEXT:    lw t0, 32(sp) # 4-byte Folded Reload
-; RV32E-NEXT:    lw t1, 28(sp) # 4-byte Folded Reload
-; RV32E-NEXT:    lw t2, 24(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw ra, 28(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw t0, 24(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a0, 20(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a1, 16(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a2, 12(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a3, 8(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a4, 4(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a5, 0(sp) # 4-byte Folded Reload
-; RV32E-NEXT:    addi sp, sp, 40
+; RV32E-NEXT:    addi sp, sp, 32
 ; RV32E-NEXT:    ret
 ;
 ; RV64E-LABEL: preserve_mostcc1:
 ; RV64E:       # %bb.0: # %entry
-; RV64E-NEXT:    addi sp, sp, -80
-; RV64E-NEXT:    sd ra, 72(sp) # 8-byte Folded Spill
-; RV64E-NEXT:    sd t0, 64(sp) # 8-byte Folded Spill
-; RV64E-NEXT:    sd t1, 56(sp) # 8-byte Folded Spill
-; RV64E-NEXT:    sd t2, 48(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    addi sp, sp, -64
+; RV64E-NEXT:    sd ra, 56(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd t0, 48(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd a0, 40(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd a1, 32(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd a2, 24(sp) # 8-byte Folded Spill
@@ -129,17 +111,15 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV64E-NEXT:    sd a4, 8(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd a5, 0(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    call standard_cc_func
-; RV64E-NEXT:    ld ra, 72(sp) # 8-byte Folded Reload
-; RV64E-NEXT:    ld t0, 64(sp) # 8-byte Folded Reload
-; RV64E-NEXT:    ld t1, 56(sp) # 8-byte Folded Reload
-; RV64E-NEXT:    ld t2, 48(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld ra, 56(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld t0, 48(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a0, 40(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a1, 32(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a2, 24(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a3, 16(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a4, 8(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a5, 0(sp) # 8-byte Folded Reload
-; RV64E-NEXT:    addi sp, sp, 80
+; RV64E-NEXT:    addi sp, sp, 64
 ; RV64E-NEXT:    ret
 entry:
   call void @standard_cc_func()

>From f883418add7f4e4175e146a52ff1d7e2139a86d0 Mon Sep 17 00:00:00 2001
From: Pengcheng Wang <wangpengcheng.pp at bytedance.com>
Date: Tue, 29 Jul 2025 11:30:51 +0800
Subject: [PATCH 4/7] Remove unnecessary include

---
 llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
index 816fd95a55ed0..214536d7f3a74 100644
--- a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
@@ -11,7 +11,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "RISCVRegisterInfo.h"
-#include "MCTargetDesc/RISCVBaseInfo.h"
 #include "RISCV.h"
 #include "RISCVSubtarget.h"
 #include "llvm/ADT/SmallSet.h"

>From 562d0a864dcbdde960b2af00762be949eb74fbc8 Mon Sep 17 00:00:00 2001
From: Pengcheng Wang <wangpengcheng.pp at bytedance.com>
Date: Tue, 29 Jul 2025 11:35:34 +0800
Subject: [PATCH 5/7] Show the save of clobbered registers

---
 llvm/docs/LangRef.rst                         |   2 +-
 llvm/lib/Target/RISCV/RISCVCallingConv.td     |   2 +-
 .../RISCV/calling-conv-preserve-most.ll       | 282 ++++++++++++++++++
 3 files changed, 284 insertions(+), 2 deletions(-)

diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index c838d96a0fa03..28746bf9d05aa 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -413,7 +413,7 @@ added in the future:
     - On AArch64 the callee preserves all general purpose registers, except
       X0-X8 and X16-X18. Not allowed with ``nest``.
 
-    - On RISC-V the callee preserve x5-x31 registers.
+    - On RISC-V the callee preserve x5-x31 except x6, x7 and x28 registers.
 
     The idea behind this convention is to support calls to runtime functions
     that have a hot path and a cold path. The hot path is usually a small piece
diff --git a/llvm/lib/Target/RISCV/RISCVCallingConv.td b/llvm/lib/Target/RISCV/RISCVCallingConv.td
index da6b95da12160..58ef100109064 100644
--- a/llvm/lib/Target/RISCV/RISCVCallingConv.td
+++ b/llvm/lib/Target/RISCV/RISCVCallingConv.td
@@ -96,6 +96,6 @@ def CSR_XLEN_F32_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F32_V_Interrupt,
 def CSR_XLEN_F64_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F64_V_Interrupt,
                                                    (sequence "X%u", 16, 31))>;
 
-def CSR_RT_MostRegs : CalleeSavedRegs<(sub CSR_Interrupt, X6, X7, X28)>;
+def CSR_RT_MostRegs : CalleeSavedRegs<(sub (sequence "X%u", 5, 31), X6, X7, X28)>;
 def CSR_RT_MostRegs_RVE : CalleeSavedRegs<(sub CSR_RT_MostRegs,
                                                (sequence "X%u", 16, 31))>;
diff --git a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
index 2fe2108679570..08340bbe0013a 100644
--- a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
+++ b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
@@ -165,3 +165,285 @@ define preserve_mostcc void @preserve_mostcc2() nounwind {
   call preserve_mostcc void @preserve_mostcc_func()
   ret void
 }
+
+; X6, X7 and X28 will be saved to registers.
+define void @preserve_mostcc3() nounwind {
+; RV32I-LABEL: preserve_mostcc3:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -16
+; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw s0, 8(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw s1, 4(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    mv a0, t1
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    mv a1, t2
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    mv a2, t3
+; RV32I-NEXT:    call preserve_mostcc_func
+; RV32I-NEXT:    mv t1, a0
+; RV32I-NEXT:    mv t2, a1
+; RV32I-NEXT:    mv t3, a2
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw s0, 8(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw s1, 4(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 16
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: preserve_mostcc3:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -32
+; RV64I-NEXT:    sd ra, 24(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd s0, 16(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd s1, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    mv a0, t1
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    mv a1, t2
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    mv a2, t3
+; RV64I-NEXT:    call preserve_mostcc_func
+; RV64I-NEXT:    mv t1, a0
+; RV64I-NEXT:    mv t2, a1
+; RV64I-NEXT:    mv t3, a2
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    ld ra, 24(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld s0, 16(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld s1, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 32
+; RV64I-NEXT:    ret
+;
+; RV32E-LABEL: preserve_mostcc3:
+; RV32E:       # %bb.0:
+; RV32E-NEXT:    addi sp, sp, -12
+; RV32E-NEXT:    sw ra, 8(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw s0, 4(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw s1, 0(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    mv a0, t1
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    mv a1, t2
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    mv a2, t3
+; RV32E-NEXT:    call preserve_mostcc_func
+; RV32E-NEXT:    mv t1, a0
+; RV32E-NEXT:    mv t2, a1
+; RV32E-NEXT:    mv t3, a2
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    lw ra, 8(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw s0, 4(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw s1, 0(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    addi sp, sp, 12
+; RV32E-NEXT:    ret
+;
+; RV64E-LABEL: preserve_mostcc3:
+; RV64E:       # %bb.0:
+; RV64E-NEXT:    addi sp, sp, -24
+; RV64E-NEXT:    sd ra, 16(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd s0, 8(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd s1, 0(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    mv a0, t1
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    mv a1, t2
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    mv a2, t3
+; RV64E-NEXT:    call preserve_mostcc_func
+; RV64E-NEXT:    mv t1, a0
+; RV64E-NEXT:    mv t2, a1
+; RV64E-NEXT:    mv t3, a2
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    ld ra, 16(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld s0, 8(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld s1, 0(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    addi sp, sp, 24
+; RV64E-NEXT:    ret
+  %1 = call i32 asm sideeffect "", "={x6}"() nounwind
+  %2 = call i32 asm sideeffect "", "={x7}"() nounwind
+  %3 = call i32 asm sideeffect "", "={x8}"() nounwind
+  %4 = call i32 asm sideeffect "", "={x9}"() nounwind
+  %5 = call i32 asm sideeffect "", "={x28}"() nounwind
+  call preserve_mostcc void @preserve_mostcc_func()
+  call void asm sideeffect "", "{x6},{x7},{x8},{x9},{x28}"(i32 %1, i32 %2, i32 %3, i32 %4, i32 %5)
+  ret void
+}
+
+; X6, X7 and X28 will be saved to the stack.
+define void @preserve_mostcc4() nounwind {
+; RV32I-LABEL: preserve_mostcc4:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -32
+; RV32I-NEXT:    sw ra, 28(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw s0, 24(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw s1, 20(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw s2, 16(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw s3, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw s4, 8(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    mv s2, t1
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    mv s3, t2
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    mv s4, t3
+; RV32I-NEXT:    call standard_cc_func
+; RV32I-NEXT:    mv t1, s2
+; RV32I-NEXT:    mv t2, s3
+; RV32I-NEXT:    mv t3, s4
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    lw ra, 28(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw s0, 24(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw s1, 20(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw s2, 16(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw s3, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw s4, 8(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 32
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: preserve_mostcc4:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -48
+; RV64I-NEXT:    sd ra, 40(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd s0, 32(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd s1, 24(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd s2, 16(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd s3, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd s4, 0(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    mv s2, t1
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    mv s3, t2
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    mv s4, t3
+; RV64I-NEXT:    call standard_cc_func
+; RV64I-NEXT:    mv t1, s2
+; RV64I-NEXT:    mv t2, s3
+; RV64I-NEXT:    mv t3, s4
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    ld ra, 40(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld s0, 32(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld s1, 24(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld s2, 16(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld s3, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld s4, 0(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 48
+; RV64I-NEXT:    ret
+;
+; RV32E-LABEL: preserve_mostcc4:
+; RV32E:       # %bb.0:
+; RV32E-NEXT:    addi sp, sp, -24
+; RV32E-NEXT:    sw ra, 20(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw s0, 16(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    sw s1, 12(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    sw t1, 8(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    sw t2, 4(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    sw t3, 0(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    call standard_cc_func
+; RV32E-NEXT:    lw t1, 8(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw t2, 4(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw t3, 0(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    #APP
+; RV32E-NEXT:    #NO_APP
+; RV32E-NEXT:    lw ra, 20(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw s0, 16(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    lw s1, 12(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    addi sp, sp, 24
+; RV32E-NEXT:    ret
+;
+; RV64E-LABEL: preserve_mostcc4:
+; RV64E:       # %bb.0:
+; RV64E-NEXT:    addi sp, sp, -48
+; RV64E-NEXT:    sd ra, 40(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd s0, 32(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    sd s1, 24(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    sd t1, 16(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    sd t2, 8(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    sd t3, 0(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    call standard_cc_func
+; RV64E-NEXT:    ld t1, 16(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld t2, 8(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld t3, 0(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    #APP
+; RV64E-NEXT:    #NO_APP
+; RV64E-NEXT:    ld ra, 40(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld s0, 32(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    ld s1, 24(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    addi sp, sp, 48
+; RV64E-NEXT:    ret
+  %1 = call i32 asm sideeffect "", "={x6}"() nounwind
+  %2 = call i32 asm sideeffect "", "={x7}"() nounwind
+  %3 = call i32 asm sideeffect "", "={x8}"() nounwind
+  %4 = call i32 asm sideeffect "", "={x9}"() nounwind
+  %5 = call i32 asm sideeffect "", "={x28}"() nounwind
+  call void @standard_cc_func()
+  call void asm sideeffect "", "{x6},{x7},{x8},{x9},{x28}"(i32 %1, i32 %2, i32 %3, i32 %4, i32 %5)
+  ret void
+}

>From 290035842ab9378903f8f234c58d30d9e2758c2e Mon Sep 17 00:00:00 2001
From: Pengcheng Wang <wangpengcheng.pp at bytedance.com>
Date: Wed, 30 Jul 2025 11:52:18 +0800
Subject: [PATCH 6/7] Fix test

---
 .../RISCV/calling-conv-preserve-most.ll       | 136 ++++++++----------
 1 file changed, 56 insertions(+), 80 deletions(-)

diff --git a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
index 08340bbe0013a..dd2ec50768c91 100644
--- a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
+++ b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
@@ -12,74 +12,69 @@ declare preserve_mostcc void @preserve_mostcc_func()
 define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV32I-LABEL: preserve_mostcc1:
 ; RV32I:       # %bb.0: # %entry
-; RV32I-NEXT:    addi sp, sp, -64
-; RV32I-NEXT:    sw ra, 60(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t0, 56(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a0, 52(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a1, 48(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a2, 44(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a3, 40(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a4, 36(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a5, 32(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a6, 28(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a7, 24(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t4, 20(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t5, 16(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t6, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    addi sp, sp, -48
+; RV32I-NEXT:    sw t0, 44(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a0, 40(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a1, 36(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a2, 32(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a3, 28(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a4, 24(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a5, 20(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a6, 16(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a7, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t4, 8(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t5, 4(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t6, 0(sp) # 4-byte Folded Spill
 ; RV32I-NEXT:    call standard_cc_func
-; RV32I-NEXT:    lw ra, 60(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t0, 56(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a0, 52(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a1, 48(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a2, 44(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a3, 40(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a4, 36(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a5, 32(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a6, 28(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a7, 24(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t4, 20(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t5, 16(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t6, 12(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    addi sp, sp, 64
+; RV32I-NEXT:    lw t0, 44(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a0, 40(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a1, 36(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a2, 32(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a3, 28(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a4, 24(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a5, 20(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a6, 16(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a7, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t4, 8(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t5, 4(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t6, 0(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 48
 ; RV32I-NEXT:    ret
 ;
 ; RV64I-LABEL: preserve_mostcc1:
 ; RV64I:       # %bb.0: # %entry
-; RV64I-NEXT:    addi sp, sp, -112
-; RV64I-NEXT:    sd ra, 104(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t0, 96(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a0, 88(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a1, 80(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a2, 72(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a3, 64(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a4, 56(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a5, 48(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a6, 40(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a7, 32(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t4, 24(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t5, 16(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t6, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    addi sp, sp, -96
+; RV64I-NEXT:    sd t0, 88(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a0, 80(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a1, 72(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a2, 64(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a3, 56(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a4, 48(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a5, 40(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a6, 32(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a7, 24(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t4, 16(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t5, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t6, 0(sp) # 8-byte Folded Spill
 ; RV64I-NEXT:    call standard_cc_func
-; RV64I-NEXT:    ld ra, 104(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t0, 96(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a0, 88(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a1, 80(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a2, 72(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a3, 64(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a4, 56(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a5, 48(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a6, 40(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a7, 32(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t4, 24(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t5, 16(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t6, 8(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    addi sp, sp, 112
+; RV64I-NEXT:    ld t0, 88(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a0, 80(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a1, 72(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a2, 64(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a3, 56(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a4, 48(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a5, 40(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a6, 32(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a7, 24(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t4, 16(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t5, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t6, 0(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 96
 ; RV64I-NEXT:    ret
 ;
 ; RV32E-LABEL: preserve_mostcc1:
 ; RV32E:       # %bb.0: # %entry
-; RV32E-NEXT:    addi sp, sp, -32
-; RV32E-NEXT:    sw ra, 28(sp) # 4-byte Folded Spill
+; RV32E-NEXT:    addi sp, sp, -28
 ; RV32E-NEXT:    sw t0, 24(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw a0, 20(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw a1, 16(sp) # 4-byte Folded Spill
@@ -88,7 +83,6 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV32E-NEXT:    sw a4, 4(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw a5, 0(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    call standard_cc_func
-; RV32E-NEXT:    lw ra, 28(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw t0, 24(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a0, 20(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a1, 16(sp) # 4-byte Folded Reload
@@ -96,13 +90,12 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV32E-NEXT:    lw a3, 8(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a4, 4(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a5, 0(sp) # 4-byte Folded Reload
-; RV32E-NEXT:    addi sp, sp, 32
+; RV32E-NEXT:    addi sp, sp, 28
 ; RV32E-NEXT:    ret
 ;
 ; RV64E-LABEL: preserve_mostcc1:
 ; RV64E:       # %bb.0: # %entry
-; RV64E-NEXT:    addi sp, sp, -64
-; RV64E-NEXT:    sd ra, 56(sp) # 8-byte Folded Spill
+; RV64E-NEXT:    addi sp, sp, -56
 ; RV64E-NEXT:    sd t0, 48(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd a0, 40(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd a1, 32(sp) # 8-byte Folded Spill
@@ -111,7 +104,6 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV64E-NEXT:    sd a4, 8(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd a5, 0(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    call standard_cc_func
-; RV64E-NEXT:    ld ra, 56(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld t0, 48(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a0, 40(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a1, 32(sp) # 8-byte Folded Reload
@@ -119,7 +111,7 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV64E-NEXT:    ld a3, 16(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a4, 8(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a5, 0(sp) # 8-byte Folded Reload
-; RV64E-NEXT:    addi sp, sp, 64
+; RV64E-NEXT:    addi sp, sp, 56
 ; RV64E-NEXT:    ret
 entry:
   call void @standard_cc_func()
@@ -129,38 +121,22 @@ entry:
 define preserve_mostcc void @preserve_mostcc2() nounwind {
 ; RV32I-LABEL: preserve_mostcc2:
 ; RV32I:       # %bb.0:
-; RV32I-NEXT:    addi sp, sp, -16
-; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
 ; RV32I-NEXT:    call preserve_mostcc_func
-; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    addi sp, sp, 16
 ; RV32I-NEXT:    ret
 ;
 ; RV64I-LABEL: preserve_mostcc2:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    addi sp, sp, -16
-; RV64I-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
 ; RV64I-NEXT:    call preserve_mostcc_func
-; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    addi sp, sp, 16
 ; RV64I-NEXT:    ret
 ;
 ; RV32E-LABEL: preserve_mostcc2:
 ; RV32E:       # %bb.0:
-; RV32E-NEXT:    addi sp, sp, -4
-; RV32E-NEXT:    sw ra, 0(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    call preserve_mostcc_func
-; RV32E-NEXT:    lw ra, 0(sp) # 4-byte Folded Reload
-; RV32E-NEXT:    addi sp, sp, 4
 ; RV32E-NEXT:    ret
 ;
 ; RV64E-LABEL: preserve_mostcc2:
 ; RV64E:       # %bb.0:
-; RV64E-NEXT:    addi sp, sp, -8
-; RV64E-NEXT:    sd ra, 0(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    call preserve_mostcc_func
-; RV64E-NEXT:    ld ra, 0(sp) # 8-byte Folded Reload
-; RV64E-NEXT:    addi sp, sp, 8
 ; RV64E-NEXT:    ret
   call preserve_mostcc void @preserve_mostcc_func()
   ret void

>From 237d6ccf2427a334a9e9aa3254de95b540299f67 Mon Sep 17 00:00:00 2001
From: Pengcheng Wang <wangpengcheng.pp at bytedance.com>
Date: Wed, 30 Jul 2025 12:09:20 +0800
Subject: [PATCH 7/7] Use CSR_Interrupt

---
 llvm/lib/Target/RISCV/RISCVCallingConv.td     |   2 +-
 .../RISCV/calling-conv-preserve-most.ll       | 136 ++++++++++--------
 2 files changed, 81 insertions(+), 57 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVCallingConv.td b/llvm/lib/Target/RISCV/RISCVCallingConv.td
index 58ef100109064..da6b95da12160 100644
--- a/llvm/lib/Target/RISCV/RISCVCallingConv.td
+++ b/llvm/lib/Target/RISCV/RISCVCallingConv.td
@@ -96,6 +96,6 @@ def CSR_XLEN_F32_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F32_V_Interrupt,
 def CSR_XLEN_F64_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F64_V_Interrupt,
                                                    (sequence "X%u", 16, 31))>;
 
-def CSR_RT_MostRegs : CalleeSavedRegs<(sub (sequence "X%u", 5, 31), X6, X7, X28)>;
+def CSR_RT_MostRegs : CalleeSavedRegs<(sub CSR_Interrupt, X6, X7, X28)>;
 def CSR_RT_MostRegs_RVE : CalleeSavedRegs<(sub CSR_RT_MostRegs,
                                                (sequence "X%u", 16, 31))>;
diff --git a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
index dd2ec50768c91..08340bbe0013a 100644
--- a/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
+++ b/llvm/test/CodeGen/RISCV/calling-conv-preserve-most.ll
@@ -12,69 +12,74 @@ declare preserve_mostcc void @preserve_mostcc_func()
 define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV32I-LABEL: preserve_mostcc1:
 ; RV32I:       # %bb.0: # %entry
-; RV32I-NEXT:    addi sp, sp, -48
-; RV32I-NEXT:    sw t0, 44(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a0, 40(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a1, 36(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a2, 32(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a3, 28(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a4, 24(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a5, 20(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a6, 16(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw a7, 12(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t4, 8(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t5, 4(sp) # 4-byte Folded Spill
-; RV32I-NEXT:    sw t6, 0(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    addi sp, sp, -64
+; RV32I-NEXT:    sw ra, 60(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t0, 56(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a0, 52(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a1, 48(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a2, 44(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a3, 40(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a4, 36(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a5, 32(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a6, 28(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw a7, 24(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t4, 20(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t5, 16(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    sw t6, 12(sp) # 4-byte Folded Spill
 ; RV32I-NEXT:    call standard_cc_func
-; RV32I-NEXT:    lw t0, 44(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a0, 40(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a1, 36(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a2, 32(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a3, 28(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a4, 24(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a5, 20(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a6, 16(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw a7, 12(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t4, 8(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t5, 4(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    lw t6, 0(sp) # 4-byte Folded Reload
-; RV32I-NEXT:    addi sp, sp, 48
+; RV32I-NEXT:    lw ra, 60(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t0, 56(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a0, 52(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a1, 48(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a2, 44(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a3, 40(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a4, 36(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a5, 32(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a6, 28(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw a7, 24(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t4, 20(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t5, 16(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    lw t6, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 64
 ; RV32I-NEXT:    ret
 ;
 ; RV64I-LABEL: preserve_mostcc1:
 ; RV64I:       # %bb.0: # %entry
-; RV64I-NEXT:    addi sp, sp, -96
-; RV64I-NEXT:    sd t0, 88(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a0, 80(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a1, 72(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a2, 64(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a3, 56(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a4, 48(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a5, 40(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a6, 32(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd a7, 24(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t4, 16(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t5, 8(sp) # 8-byte Folded Spill
-; RV64I-NEXT:    sd t6, 0(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    addi sp, sp, -112
+; RV64I-NEXT:    sd ra, 104(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t0, 96(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a0, 88(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a1, 80(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a2, 72(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a3, 64(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a4, 56(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a5, 48(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a6, 40(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd a7, 32(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t4, 24(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t5, 16(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    sd t6, 8(sp) # 8-byte Folded Spill
 ; RV64I-NEXT:    call standard_cc_func
-; RV64I-NEXT:    ld t0, 88(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a0, 80(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a1, 72(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a2, 64(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a3, 56(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a4, 48(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a5, 40(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a6, 32(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld a7, 24(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t4, 16(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t5, 8(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    ld t6, 0(sp) # 8-byte Folded Reload
-; RV64I-NEXT:    addi sp, sp, 96
+; RV64I-NEXT:    ld ra, 104(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t0, 96(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a0, 88(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a1, 80(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a2, 72(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a3, 64(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a4, 56(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a5, 48(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a6, 40(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld a7, 32(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t4, 24(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t5, 16(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    ld t6, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 112
 ; RV64I-NEXT:    ret
 ;
 ; RV32E-LABEL: preserve_mostcc1:
 ; RV32E:       # %bb.0: # %entry
-; RV32E-NEXT:    addi sp, sp, -28
+; RV32E-NEXT:    addi sp, sp, -32
+; RV32E-NEXT:    sw ra, 28(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw t0, 24(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw a0, 20(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw a1, 16(sp) # 4-byte Folded Spill
@@ -83,6 +88,7 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV32E-NEXT:    sw a4, 4(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    sw a5, 0(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    call standard_cc_func
+; RV32E-NEXT:    lw ra, 28(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw t0, 24(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a0, 20(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a1, 16(sp) # 4-byte Folded Reload
@@ -90,12 +96,13 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV32E-NEXT:    lw a3, 8(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a4, 4(sp) # 4-byte Folded Reload
 ; RV32E-NEXT:    lw a5, 0(sp) # 4-byte Folded Reload
-; RV32E-NEXT:    addi sp, sp, 28
+; RV32E-NEXT:    addi sp, sp, 32
 ; RV32E-NEXT:    ret
 ;
 ; RV64E-LABEL: preserve_mostcc1:
 ; RV64E:       # %bb.0: # %entry
-; RV64E-NEXT:    addi sp, sp, -56
+; RV64E-NEXT:    addi sp, sp, -64
+; RV64E-NEXT:    sd ra, 56(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd t0, 48(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd a0, 40(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd a1, 32(sp) # 8-byte Folded Spill
@@ -104,6 +111,7 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV64E-NEXT:    sd a4, 8(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    sd a5, 0(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    call standard_cc_func
+; RV64E-NEXT:    ld ra, 56(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld t0, 48(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a0, 40(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a1, 32(sp) # 8-byte Folded Reload
@@ -111,7 +119,7 @@ define preserve_mostcc void @preserve_mostcc1() nounwind {
 ; RV64E-NEXT:    ld a3, 16(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a4, 8(sp) # 8-byte Folded Reload
 ; RV64E-NEXT:    ld a5, 0(sp) # 8-byte Folded Reload
-; RV64E-NEXT:    addi sp, sp, 56
+; RV64E-NEXT:    addi sp, sp, 64
 ; RV64E-NEXT:    ret
 entry:
   call void @standard_cc_func()
@@ -121,22 +129,38 @@ entry:
 define preserve_mostcc void @preserve_mostcc2() nounwind {
 ; RV32I-LABEL: preserve_mostcc2:
 ; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -16
+; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
 ; RV32I-NEXT:    call preserve_mostcc_func
+; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 16
 ; RV32I-NEXT:    ret
 ;
 ; RV64I-LABEL: preserve_mostcc2:
 ; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -16
+; RV64I-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
 ; RV64I-NEXT:    call preserve_mostcc_func
+; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 16
 ; RV64I-NEXT:    ret
 ;
 ; RV32E-LABEL: preserve_mostcc2:
 ; RV32E:       # %bb.0:
+; RV32E-NEXT:    addi sp, sp, -4
+; RV32E-NEXT:    sw ra, 0(sp) # 4-byte Folded Spill
 ; RV32E-NEXT:    call preserve_mostcc_func
+; RV32E-NEXT:    lw ra, 0(sp) # 4-byte Folded Reload
+; RV32E-NEXT:    addi sp, sp, 4
 ; RV32E-NEXT:    ret
 ;
 ; RV64E-LABEL: preserve_mostcc2:
 ; RV64E:       # %bb.0:
+; RV64E-NEXT:    addi sp, sp, -8
+; RV64E-NEXT:    sd ra, 0(sp) # 8-byte Folded Spill
 ; RV64E-NEXT:    call preserve_mostcc_func
+; RV64E-NEXT:    ld ra, 0(sp) # 8-byte Folded Reload
+; RV64E-NEXT:    addi sp, sp, 8
 ; RV64E-NEXT:    ret
   call preserve_mostcc void @preserve_mostcc_func()
   ret void



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