[llvm] 7e3217c - [RISCV] Avoid fatal error for SiFive CLIC preemptible frame pointers (#217949)

[via llvm-commits]

Author: Zeyi Xu
Date: 2026-08-23T11:14:17+08:00
New Revision: 7e3217ca7c61d1eed7f092c46141c8c7a96ef19e

URL: https://github.com/llvm/llvm-project/commit/7e3217ca7c61d1eed7f092c46141c8c7a96ef19e
DIFF: https://github.com/llvm/llvm-project/commit/7e3217ca7c61d1eed7f092c46141c8c7a96ef19e.diff

LOG: [RISCV]  Avoid fatal error for SiFive CLIC preemptible frame pointers (#217949)

SiFive CLIC `preemptible` interrupt handlers currently use `s0` to
preserve `mcause` and cannot be generated with a frame pointer. At
`-O0`, Clang enables frame pointers by default, causing the fatal error
to produce a backend crash report.

This commit switches to `DiagnosticInfoUnsupported` to emit a regular
source-located error and suggest considering `-fomit-frame-pointer`.

This does not change the existing code generation restriction.

Fixes https://github.com/llvm/llvm-project/issues/217936

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.md
    llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    llvm/test/CodeGen/RISCV/sifive-interrupt-attr-err.ll

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.md b/clang/docs/ReleaseNotes.md
index fcd58e38261bb..ca0dbfa2af229 100644
--- a/clang/docs/ReleaseNotes.md
+++ b/clang/docs/ReleaseNotes.md
@@ -600,6 +600,9 @@ features cannot lower the translation-unit ABI level;
 - Added a new warning when the same interrupt type is specified more than
   once in a RISC-V `interrupt` attribute.
 
+- SiFive CLIC preemptible interrupt handlers now diagnose unsupported frame
+  pointers instead of producing a backend fatal error.
+
 - Added `-march=native` for better compatibility with ARM, AArch64, and X86. This
   option will be treated like `-mcpu=native` if `-mcpu` is not present. If
   `-mcpu` is present, the ISA will be selected from the host CPU and the tune

diff  --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 9406b697882d7..c6b859da32b5a 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -26406,8 +26406,10 @@ SDValue RISCVTargetLowering::LowerFormalArguments(
       reportFatalUsageError("'rnmi' interrupt kind requires Srnmi extension");
     const TargetFrameLowering *TFI = Subtarget.getFrameLowering();
     if (Kind.starts_with("SiFive-CLIC-preemptible") && TFI->hasFP(MF))
-      reportFatalUsageError("'SiFive-CLIC-preemptible' interrupt kinds cannot "
-                            "have a frame pointer");
+      Func.getContext().diagnose(DiagnosticInfoUnsupported{
+          Func,
+          "'SiFive-CLIC-preemptible' interrupt functions cannot have a frame "
+          "pointer"});
   }
 
   EVT PtrVT = getPointerTy(DAG.getDataLayout());

diff  --git a/llvm/test/CodeGen/RISCV/sifive-interrupt-attr-err.ll b/llvm/test/CodeGen/RISCV/sifive-interrupt-attr-err.ll
index ccc11b74f78e7..f0e1f16cf6e54 100644
--- a/llvm/test/CodeGen/RISCV/sifive-interrupt-attr-err.ll
+++ b/llvm/test/CodeGen/RISCV/sifive-interrupt-attr-err.ll
@@ -3,9 +3,9 @@
 ; RUN: not llc -mtriple riscv64-unknown-elf -mattr=+experimental-xsfmclic -o - %s 2>&1 \
 ; RUN:   | FileCheck %s
 
-;; Test that these report fatal errors.
+;; Test that these report regular errors.
 
-; CHECK: LLVM ERROR: 'SiFive-CLIC-preemptible' interrupt kinds cannot have a frame pointer
+; CHECK: error: <unknown>:0:0: in function preemptible void (): 'SiFive-CLIC-preemptible' interrupt functions cannot have a frame pointer
 
 define void @preemptible() "interrupt"="SiFive-CLIC-preemptible" "frame-pointer"="all" {
   ret void