Adjust the calleeSavedRegs on top frame for LoongArch64/RISCV64 (dotnet#100962)

The frame layout:
   |                       |
   |-----------------------|
   |  incoming arguments   |
   +=======================+ <---- Caller's SP
   |  Varargs regs space   | // Only for varargs main functions; not used for LA64.
   |-----------------------|
   |    MonitorAcquired    | // 8 bytes; for synchronized methods
   |-----------------------|
   |        PSP slot       | // 8 bytes (omitted in NativeAOT ABI)
   |-----------------------|
   |Callee saved registers | // multiple of 8 bytes, not includting FP/RA
   |-----------------------|
   |      Saved RA         | // 8 bytes
   |-----------------------|
   |      Saved FP         | // 8 bytes
   |-----------------------|
   |  possible GS cookie   |
   |-----------------------|
   | locals, temps, etc.   |
   |-----------------------|
   |  possible GS cookie   |
   |-----------------------|
   |   Outgoing arg space  | // multiple of 8 bytes; if required (i.e., #outsz != 0)
   |-----------------------| <---- Ambient SP
   |       |               |
   ~       | Stack grows   ~
   |       | downward      |

Author: shushanhf

src/coreclr/jit/codegen.h

@@ -437,7 +437,7 @@ class CodeGen final : public CodeGenInterface
 
     FuncletFrameInfoDsc genFuncletInfo;
 
-#elif defined(TARGET_LOONGARCH64)
+#elif defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
 
     // A set of information that is used by funclet prolog and epilog generation.
     // It is collected once, before funclet prologs and epilogs are generated,
@@ -448,26 +448,6 @@ class CodeGen final : public CodeGenInterface
         int fiFunction_CallerSP_to_FP_delta; // Delta between caller SP and the frame pointer in the parent function
                                              // (negative)
         int fiSP_to_CalleeSaved_delta;       // CalleeSaved register save offset from SP (positive)
-        int fiCalleeSavedPadding;            // CalleeSaved offset padding (positive)
-        int fiSP_to_PSP_slot_delta;          // PSP slot offset from SP (positive)
-        int fiCallerSP_to_PSP_slot_delta;    // PSP slot offset from Caller SP (negative)
-        int fiSpDelta;                       // Stack pointer delta (negative)
-    };
-
-    FuncletFrameInfoDsc genFuncletInfo;
-
-#elif defined(TARGET_RISCV64)
-
-    // A set of information that is used by funclet prolog and epilog generation.
-    // It is collected once, before funclet prologs and epilogs are generated,
-    // and used by all funclet prologs and epilogs, which must all be the same.
-    struct FuncletFrameInfoDsc
-    {
-        regMaskTP fiSaveRegs;                // Set of callee-saved registers saved in the funclet prolog (includes RA)
-        int fiFunction_CallerSP_to_FP_delta; // Delta between caller SP and the frame pointer in the parent function
-                                             // (negative)
-        int fiSP_to_CalleeSaved_delta;       // CalleeSaved register save offset from SP (positive)
-        int fiCalleeSavedPadding;            // CalleeSaved offset padding (positive)
         int fiSP_to_PSP_slot_delta;          // PSP slot offset from SP (positive)
         int fiCallerSP_to_PSP_slot_delta;    // PSP slot offset from Caller SP (negative)
         int fiSpDelta;                       // Stack pointer delta (negative)
@@ -1272,7 +1252,6 @@ class CodeGen final : public CodeGenInterface
     void        genJmpMethod(GenTree* jmp);
     BasicBlock* genCallFinally(BasicBlock* block);
 #if defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
-    // TODO: refactor for LA.
     void genCodeForJumpCompare(GenTreeOpCC* tree);
 #endif
 #if defined(TARGET_ARM64)

src/coreclr/jit/codegencommon.cpp

@@ -4744,20 +4744,13 @@ void CodeGen::genFinalizeFrame()
 #endif // defined(TARGET_XARCH)
 
 #if defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
-    if (isFramePointerUsed())
-    {
-        // For a FP based frame we have to push/pop the FP register
-        //
-        maskCalleeRegsPushed |= RBM_FPBASE;
+    // This assert check that we are not using REG_FP
+    assert(!regSet.rsRegsModified(RBM_FPBASE));
 
-        // This assert check that we are not using REG_FP
-        // as both the frame pointer and as a codegen register
-        //
-        assert(!regSet.rsRegsModified(RBM_FPBASE));
-    }
+    assert(isFramePointerUsed());
+    // we always push FP/RA.  See genPushCalleeSavedRegisters
+    maskCalleeRegsPushed |= (RBM_FPBASE | RBM_RA);
 
-    // we always push RA.  See genPushCalleeSavedRegisters
-    maskCalleeRegsPushed |= RBM_RA;
 #endif // TARGET_LOONGARCH64 || TARGET_RISCV64
 
     compiler->compCalleeRegsPushed = genCountBits(maskCalleeRegsPushed);