[RISCV] Correct the CFA offsets for stack probing.

[topperc]

We need to take into account that we already did a FirstSPAdjust.

Fixes #164805.

[llvmbot]

@llvm/pr-subscribers-backend-risc-v

Author: Craig Topper (topperc)

Changes

We need to take into account that we already did a FirstSPAdjust.

Fixes #164805.

---

Full diff: https://github.com/llvm/llvm-project/pull/166616.diff

2 Files Affected:

• (modified) llvm/lib/Target/RISCV/RISCVFrameLowering.cpp (+4-2)
• (modified) llvm/test/CodeGen/RISCV/rvv/stack-probing-dynamic.ll (+4-4)

diff --git a/llvm/lib/Target/RISCV/RISCVFrameLowering.cpp b/llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
index b37b7405a660f..f881c4c79d444 100644
--- a/llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
@@ -789,6 +789,8 @@ void RISCVFrameLowering::allocateStack(MachineBasicBlock &MBB,
 
   // Unroll the probe loop depending on the number of iterations.
   if (Offset < ProbeSize * 5) {
+    uint64_t CFAAdjust = RealStackSize - Offset;
+
     uint64_t CurrentOffset = 0;
     while (CurrentOffset + ProbeSize <= Offset) {
       RI->adjustReg(MBB, MBBI, DL, SPReg, SPReg,
@@ -802,7 +804,7 @@ void RISCVFrameLowering::allocateStack(MachineBasicBlock &MBB,
 
       CurrentOffset += ProbeSize;
       if (EmitCFI)
-        CFIBuilder.buildDefCFAOffset(CurrentOffset);
+        CFIBuilder.buildDefCFAOffset(CurrentOffset + CFAAdjust);
     }
 
     uint64_t Residual = Offset - CurrentOffset;
@@ -810,7 +812,7 @@ void RISCVFrameLowering::allocateStack(MachineBasicBlock &MBB,
       RI->adjustReg(MBB, MBBI, DL, SPReg, SPReg,
                     StackOffset::getFixed(-Residual), Flag, getStackAlign());
       if (EmitCFI)
-        CFIBuilder.buildDefCFAOffset(Offset);
+        CFIBuilder.buildDefCFAOffset(RealStackSize);
 
       if (DynAllocation) {
         // s[d|w] zero, 0(sp)
diff --git a/llvm/test/CodeGen/RISCV/rvv/stack-probing-dynamic.ll b/llvm/test/CodeGen/RISCV/rvv/stack-probing-dynamic.ll
index d666832cf6e0b..c79fb0f91b21f 100644
--- a/llvm/test/CodeGen/RISCV/rvv/stack-probing-dynamic.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/stack-probing-dynamic.ll
@@ -460,9 +460,9 @@ define void @reserved_call_frame(i64 %n) #0 {
 ; RV64I-NEXT:    lui a0, 1
 ; RV64I-NEXT:    sub sp, sp, a0
 ; RV64I-NEXT:    sd zero, 0(sp)
-; RV64I-NEXT:    .cfi_def_cfa_offset 4096
+; RV64I-NEXT:    .cfi_def_cfa_offset 6128
 ; RV64I-NEXT:    addi sp, sp, -48
-; RV64I-NEXT:    .cfi_def_cfa_offset 4144
+; RV64I-NEXT:    .cfi_def_cfa_offset 6176
 ; RV64I-NEXT:    lui a0, 1
 ; RV64I-NEXT:    add a0, sp, a0
 ; RV64I-NEXT:    call callee_stack_args
@@ -485,9 +485,9 @@ define void @reserved_call_frame(i64 %n) #0 {
 ; RV32I-NEXT:    lui a0, 1
 ; RV32I-NEXT:    sub sp, sp, a0
 ; RV32I-NEXT:    sw zero, 0(sp)
-; RV32I-NEXT:    .cfi_def_cfa_offset 4096
+; RV32I-NEXT:    .cfi_def_cfa_offset 6128
 ; RV32I-NEXT:    addi sp, sp, -80
-; RV32I-NEXT:    .cfi_def_cfa_offset 4176
+; RV32I-NEXT:    .cfi_def_cfa_offset 6208
 ; RV32I-NEXT:    lui a0, 1
 ; RV32I-NEXT:    addi a0, a0, 36
 ; RV32I-NEXT:    add a0, sp, a0

[s-barannikov]

The changes to the test look correct, but I'm not very familiar with the implementation.

[kito-cheng]

LGTM :)