[Cherry-pick][RESOLVED] [BUILD] Fix mac build CI (#7997) (#541)

Summary:
⚠️ **MERGE CONFLICTS DETECTED** ⚠️

This cherry-pick contains merge conflicts that require manual resolution.

Original Commit: 832c62d
Original Author: Thomas Raoux
Original Date: 2025-08-28 12:36:28 -0700

**Action Required:**
1. Check out this branch locally
2. Resolve the merge conflicts in the affected files
3. Commit the resolved changes
4. Update this PR

Original commit message:
```
[BUILD] Fix mac build CI (#7997)

We were picking the wrong clang after image upgrade.
Solution mostly from chatgpt
```

This PR was automatically cherry-picked from the upstream triton-lang/triton repository.
The conflicts have been committed with conflict markers for easier resolution.

Pull Request resolved: #541

Reviewed By: dshi7

Differential Revision: D85968641

Pulled By: agron911

fbshipit-source-id: 5fd5edd70bb6738c2e4958673917db99ccc393fd

Author: agron911

.github/workflows/build-macos.yml

@@ -0,0 +1,135 @@
+name: Build MacOS
+
+on:
+  workflow_call:
+    inputs:
+      matrix:
+        required: true
+        type: string
+
+jobs:
+  build-macos:
+    runs-on: ${{ matrix.runner }}
+    strategy:
+      matrix:
+        runner: ${{ fromJson(inputs.matrix) }}
+    timeout-minutes: 60
+    env:
+      RUNNER_TYPE: ${{ matrix.runner[0] }}
+      TRITON_BUILD_WITH_CLANG_LLD: "TRUE"
+    name: Build MacOS
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          submodules: "true"
+      - name: Install brew dependencies
+        run: |
+          brew update
+          brew install ccache llvm@19 lld coreutils
+      - name: Compute cache keys
+        id: cache-key
+        run: |
+          llvm_file="cmake/llvm-hash.txt"
+          nvidia_file="cmake/nvidia-toolchain-version.json"
+          json_file="cmake/json-version.txt"
+
+          # Check if files exist before proceeding
+          if [[ ! -f "$llvm_file" || ! -f "$nvidia_file" || ! -f "$json_file" ]]; then
+            echo "Error: Required dependency files are missing."
+            exit 1
+          fi
+
+          # Process the files if they exist
+          echo "llvm=$(cat $llvm_file | cut -c 1-8)" >> $GITHUB_OUTPUT
+          echo "nvidia=$(sha256sum $nvidia_file | cut -d ' ' -f 1)" >> $GITHUB_OUTPUT
+          echo "json=$(cat $json_file)" >> $GITHUB_OUTPUT
+          echo "datetime=$(date -u -Iseconds)" >> $GITHUB_OUTPUT
+        shell: bash
+      - name: Cache build dependencies
+        uses: actions/cache@v4
+        with:
+          # Note that we cannot use environment variables here given there is
+          # no shell to interpret them in the paths.
+          path: |
+            ~/.triton/llvm
+            ~/.triton/nvidia
+            ~/.triton/json
+          key: ${{ runner.os }}-${{ runner.arch }}-llvm-${{ steps.cache-key.outputs.llvm }}-nvidia-${{ steps.cache-key.outputs.nvidia }}-json-${{ steps.cache-key.outputs.json }}
+      - # Cache ~/.cache/ccache to speed up compilation.
+        #
+        # On branch `main` we always start from an empty cache, i.e. we skip the
+        # "restore" step.  This is to prevent the caches from accumulating stale
+        # files over time.
+        name: Restore cache of ccache and Triton compilation artifacts
+        id: restore-build-cache
+        if: github.ref != 'refs/heads/main'
+        uses: actions/cache/restore@v4
+        with:
+          path: |
+            ~/.ccache
+          # Restore the most recent cache entry.
+          restore-keys: |
+            triton-artifacts-${{ runner.os }}-${{ runner.arch }}-${{ env.RUNNER_TYPE }}-llvm-${{ steps.cache-key.outputs.llvm }}-
+            triton-artifacts-${{ runner.os }}-${{ runner.arch }}-${{ env.RUNNER_TYPE }}-
+          # We expect this cache key never to hit and for us to fall back
+          # unconditionally to the restore-key, so it doesn't actually matter
+          # what we put here (so long as it doesn't hit an existing key).
+          key: triton-artifacts-${{ runner.os }}-${{ runner.arch }}-${{ env.RUNNER_TYPE }}-llvm-${{ steps.cache-key.outputs.llvm }}-${{ steps.cache-key.outputs.datetime }}
+      - name: Inspect cache directories
+        run: |
+          mkdir -p ~/.triton
+          du -h -d 1 ~/.triton
+
+          mkdir -p ~/.ccache
+          du -h -d 1 ~/.ccache
+      - name: Update PATH
+        run: |
+          echo "$HOME/.local/bin" >> $GITHUB_PATH
+          echo "/opt/homebrew/opt/llvm/bin" >> $GITHUB_PATH
+      - name: Create venv
+        run: |
+          python3 -m venv ~/.venv
+          source ~/.venv/bin/activate
+          python3 -m pip install --upgrade pip
+      - name: Install Triton
+        env:
+          TRITON_BUILD_WITH_O1: "true"
+          # macos-latest has 3 vcpus and 7GB DRAM, to save memory we limit the number of jobs to 3
+          # https://docs.github.com/en/actions/reference/github-hosted-runners-reference#standard-github-hosted-runners-for-public-repositories
+          MAX_JOBS: 3
+          # Add elapsed time in seconds to ninja status to monitor where build stalls
+          NINJA_STATUS: "[%f/%t, %es elapsed] "
+        run: |
+          source ~/.venv/bin/activate
+          echo "PATH is '$PATH'"
+          ccache --zero-stats
+          export PATH="/opt/homebrew/opt/llvm@19/bin:$PATH"
+          export CC="/opt/homebrew/opt/llvm@19/bin/clang"
+          export CXX="/opt/homebrew/opt/llvm@19/bin/clang++"
+          export CXXFLAGS="-stdlib=libc++"
+          export LDFLAGS="-L/opt/homebrew/opt/llvm@19/lib"
+          which clang++
+          clang++ --version
+          make dev-install
+      - name: CCache Stats
+        run: ccache --print-stats
+      - name: Inspect cache directories
+        run: |
+          mkdir -p ~/.triton
+          du -h -d 1 ~/.triton
+
+          mkdir -p ~/.ccache
+          du -h -d 1 ~/.ccache
+      - # If we're on branch `main`, save the ccache Triton compilation artifacts
+        # to the cache so they can be used by other (non-main) CI runs.
+        #
+        # (It wouldn't be a problem to save the cache on every run, because github
+        # evicts cache entries LRU, but maybe this saves a bit of time in CI.)
+        name: Save ccache and Triton compilation artifacts to cache
+        if: github.ref == 'refs/heads/main'
+        uses: actions/cache/save@v4
+        with:
+          path: |
+            ~/.ccache
+          key: triton-artifacts-${{ runner.os }}-${{ runner.arch }}-${{ env.RUNNER_TYPE }}-llvm-${{ steps.cache-key.outputs.llvm }}-${{ steps.cache-key.outputs.datetime }}