[RISCV] Fix incorrect FP base CFI offset for variable argument functions

When the FP exists, the FP base CFI directive offset should take the size of variable arguments into account.

Differential Revision: https://reviews.llvm.org/D73862

(cherry picked from commit 64f4172)

Author: ShivaChen

llvm/lib/Target/RISCV/RISCVFrameLowering.cpp

@@ -181,9 +181,9 @@ void RISCVFrameLowering::emitPrologue(MachineFunction &MF,
     adjustReg(MBB, MBBI, DL, FPReg, SPReg,
               StackSize - RVFI->getVarArgsSaveSize(), MachineInstr::FrameSetup);
 
-    // Emit ".cfi_def_cfa $fp, 0"
+    // Emit ".cfi_def_cfa $fp, -RVFI->getVarArgsSaveSize()"
     unsigned CFIIndex = MF.addFrameInst(MCCFIInstruction::createDefCfa(
-        nullptr, RI->getDwarfRegNum(FPReg, true), 0));
+        nullptr, RI->getDwarfRegNum(FPReg, true), -RVFI->getVarArgsSaveSize()));
     BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
         .addCFIIndex(CFIIndex);
   }

llvm/test/CodeGen/RISCV/vararg.ll

@@ -64,7 +64,7 @@ define i32 @va1(i8* %fmt, ...) {
 ; ILP32-ILP32F-WITHFP-NEXT:    .cfi_offset ra, -36
 ; ILP32-ILP32F-WITHFP-NEXT:    .cfi_offset s0, -40
 ; ILP32-ILP32F-WITHFP-NEXT:    addi s0, sp, 16
-; ILP32-ILP32F-WITHFP-NEXT:    .cfi_def_cfa s0, 0
+; ILP32-ILP32F-WITHFP-NEXT:    .cfi_def_cfa s0, 32
 ; ILP32-ILP32F-WITHFP-NEXT:    mv a0, a1
 ; ILP32-ILP32F-WITHFP-NEXT:    sw a7, 28(s0)
 ; ILP32-ILP32F-WITHFP-NEXT:    sw a6, 24(s0)
@@ -124,7 +124,7 @@ define i32 @va1(i8* %fmt, ...) {
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    .cfi_offset ra, -72
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    .cfi_offset s0, -80
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    addi s0, sp, 32
-; LP64-LP64F-LP64D-WITHFP-NEXT:    .cfi_def_cfa s0, 0
+; LP64-LP64F-LP64D-WITHFP-NEXT:    .cfi_def_cfa s0, 64
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    sd a1, 8(s0)
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    sd a7, 56(s0)
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    sd a6, 48(s0)
@@ -1809,7 +1809,7 @@ define i32 @va_large_stack(i8* %fmt, ...) {
 ; ILP32-ILP32F-WITHFP-NEXT:    .cfi_offset ra, -36
 ; ILP32-ILP32F-WITHFP-NEXT:    .cfi_offset s0, -40
 ; ILP32-ILP32F-WITHFP-NEXT:    addi s0, sp, 2000
-; ILP32-ILP32F-WITHFP-NEXT:    .cfi_def_cfa s0, 0
+; ILP32-ILP32F-WITHFP-NEXT:    .cfi_def_cfa s0, 32
 ; ILP32-ILP32F-WITHFP-NEXT:    lui a0, 24414
 ; ILP32-ILP32F-WITHFP-NEXT:    addi a0, a0, -1728
 ; ILP32-ILP32F-WITHFP-NEXT:    sub sp, sp, a0
@@ -1937,7 +1937,7 @@ define i32 @va_large_stack(i8* %fmt, ...) {
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    .cfi_offset ra, -72
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    .cfi_offset s0, -80
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    addi s0, sp, 1968
-; LP64-LP64F-LP64D-WITHFP-NEXT:    .cfi_def_cfa s0, 0
+; LP64-LP64F-LP64D-WITHFP-NEXT:    .cfi_def_cfa s0, 64
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    lui a0, 24414
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    addiw a0, a0, -1680
 ; LP64-LP64F-LP64D-WITHFP-NEXT:    sub sp, sp, a0