[llvm] [libc] Add riscv64 qemu precommit CI for overlay mode. (PR #192816)

[via llvm-commits]

https://github.com/lntue updated https://github.com/llvm/llvm-project/pull/192816

>From a94d9639aaacfd57547adaffb74831a041e8a10d Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Mon, 13 Jul 2026 19:50:18 +0000
Subject: [PATCH] [libc][Add riscv64 qemu overlay mode to precommit CI.

---
 .github/workflows/libc-overlay-tests.yml | 76 +++++++++++++++++++++++-
 1 file changed, 74 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/libc-overlay-tests.yml b/.github/workflows/libc-overlay-tests.yml
index 09fdfc29dc0e8..cfa51aa918bce 100644
--- a/.github/workflows/libc-overlay-tests.yml
+++ b/.github/workflows/libc-overlay-tests.yml
@@ -9,8 +9,9 @@ on:
       - '.github/workflows/libc-overlay-tests.yml'
 
 jobs:
-  build:
+  native:
     if: github.repository_owner == 'llvm'
+    name: ${{ matrix.os }} - ${{ matrix.compiler.c_compiler }}
     timeout-minutes: 30
     runs-on: ${{ matrix.os }}
     container: ${{ matrix.container || null }}
@@ -21,7 +22,7 @@ jobs:
         include:
           # TODO: add linux gcc when it is fixed
           - os: ubuntu-24.04
-            container: 'ghcr.io/llvm/libc-ubuntu-24.04:latest at sha256:a902fb53bdad5e4a4bb6c11b6584e717a7b3d6e886f1ea58e11f95e46226249c'
+            container: 'ghcr.io/llvm/libc-ubuntu-24.04:latest at sha256:c6e2ee2a9bf5cebd51fd27dd8e85381c2f73d90e091c764082f8ad528ee18918'
             compiler:
               c_compiler: clang-23
               cpp_compiler: clang++-23
@@ -102,9 +103,80 @@ jobs:
         --parallel 
         --target libc
 
+    - name: Build Test
+      run: >
+        cmake 
+        --build build 
+        --parallel 
+        --target check-libc-build
+
     - name: Test
       run: >
         cmake 
         --build build 
         --parallel 
         --target check-libc
+
+  qemu:
+    if: github.repository_owner == 'llvm'
+    name: qemu - ${{ matrix.arch }} - ${{ matrix.c_compiler }}
+    runs-on: ubuntu-24.04
+    timeout-minutes: 60
+    container: 'ghcr.io/llvm/libc-ubuntu-24.04:latest at sha256:c6e2ee2a9bf5cebd51fd27dd8e85381c2f73d90e091c764082f8ad528ee18918'
+    strategy:
+      # Set fail-fast to false to ensure that feedback is delivered for all matrix combinations.
+      fail-fast: false
+      matrix:
+        include:
+          - arch: riscv64
+            target_triple: riscv64-linux-gnu
+            c_compiler: clang-23
+            cxx_compiler: clang++-23
+            mpfr_path: /usr/riscv64-linux-gnu
+            mpc_path: riscv64-linux-gnu
+    steps:
+      - name: Checkout LLVM
+        uses: actions/checkout at 8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          persist-credentials: false
+
+      - name: Setup ccache
+        uses: hendrikmuhs/ccache-action at 33522472633dbd32578e909b315f5ee43ba878ce # v1.2.22
+        with:
+          max-size: 1G
+          key: libc_qemu_overlay_${{ matrix.arch }}_${{ matrix.c_compiler }}
+          variant: sccache
+
+      - name: Create QEMU wrapper
+        run: |
+          mkdir build
+          cat << 'EOF' > /__w/llvm-project/llvm-project/build/qemu-wrapper.sh
+          #!/bin/bash
+          qemu-${{ matrix.arch }}-static -L /usr/${{ matrix.target_triple }} "$@"
+          EOF
+          chmod +x /__w/llvm-project/llvm-project/build/qemu-wrapper.sh
+
+      - name: Configure CMake
+        run: |
+          cmake -B build -S runtimes -G Ninja \
+            -DLLVM_ENABLE_RUNTIMES=libc \
+            -DCMAKE_C_COMPILER=${{ matrix.c_compiler }} \
+            -DCMAKE_CXX_COMPILER=${{ matrix.cxx_compiler }} \
+            -DCMAKE_BUILD_TYPE=Release \
+            -DLLVM_USE_LINKER=lld-23 \
+            -DLIBC_TARGET_TRIPLE=${{ matrix.target_triple}} \
+            -DLLVM_LIBC_MPFR_INSTALL_PATH="${{ matrix.mpfr_path }}" \
+            -DLIBC_MPC_INSTALL_PATH="${{ matrix.mpc_path }}" \
+            -DCMAKE_CROSSCOMPILING_EMULATOR=/__w/llvm-project/llvm-project/build/qemu-wrapper.sh
+
+      - name: Build
+        run: |
+          cmake --build build --parallel --target libc
+
+      - name: Build Test
+        run: |
+          cmake --build build --parallel --target check-libc-build
+
+      - name: Run Test
+        run: |
+          cmake --build build --parallel --target check-libc