[CI] Run the LLVM 22 Valgrind row against the from-source recipe

The Valgrind memcheck row ran against apt.llvm.org's clang-22, whose
-O2 x86_64 binaries read uninitialised bitfield padding across
AST/Sema/CodeGen (llvm/llvm-project#194147) -- ~399 distinct clang/LLVM
read sites, none in a clad frame, tripping --error-exitcode on nearly
the whole suite. The from-source llvm-release recipe (Release+Asserts)
had never been exercised by this row: the matrix defaulted every Linux
row to flavor=system (apt) via `matrix.flavor || 'system'`, which cannot
emit the empty flavor the recipe needs.

Route the row through the recipe (use-recipe selects setup-llvm's empty
flavor) and run memcheck with no suppression file plus
--gen-suppressions=all, so the recipe build's raw behaviour is visible:
a clean row means it is valgrind-clean and no suppressions are needed, a
failing one hands us the exact frames to triage. Drop the ~47
noise-driven `XFAIL: valgrind` markers accordingly; NumDiff.C keeps its
timeout marker and the i586 Pointers.C XFAIL stays.

Author: vgvassilev

.github/workflows/ci.yml

@@ -101,12 +101,16 @@ jobs:
             extra_packages: 'libtrilinos-kokkos-dev ninja-build'
             extra_cmake_options: '-G Ninja'
 
-          - name: ubu24-clang19-runtime20-vg
+          - name: ubu24-clang20-runtime22-vg
             os: ubuntu-24.04
-            compiler: clang-19
+            compiler: clang-20
             extra_packages: 'valgrind'
             extra_cmake_options: '-DCLAD_TEST_USE_VG=On'
-            clang-runtime: '20'
+            clang-runtime: '22'
+            # Run Valgrind against the from-source llvm-release recipe
+            # (Release+Asserts) rather than apt, to measure whether the
+            # apt binaries' -O2 uninitialised-read noise is present there.
+            use-recipe: 'true'
 
           - name: ubu24-arm-clang16-runtime17-shared-libs
             os: ubuntu-24.04-arm
@@ -186,13 +190,16 @@ jobs:
           fi
         fi
         echo "ncpus=$ncpus" >> $GITHUB_ENV
-    - name: Setup LLVM ${{ matrix.clang-runtime }}${{ matrix.flavor && format(' [{0}]', matrix.flavor) || '' }}
+    - name: Setup LLVM ${{ matrix.clang-runtime }}${{ matrix.use-recipe == 'true' && ' [recipe]' || (matrix.flavor && format(' [{0}]', matrix.flavor) || '') }}
       if: runner.os != 'Windows'
       uses: compiler-research/ci-workflows/actions/setup-llvm@main
       with:
         version: ${{ matrix.clang-runtime }}
         os:      ${{ matrix.self-hosted-os || matrix.os }}
-        flavor:  ${{ matrix.flavor || 'system' }}
+        # use-recipe=true selects setup-llvm's empty flavor (the vanilla
+        # from-source llvm-release recipe); the `|| 'system'` default can't
+        # emit that empty string on its own.
+        flavor:  ${{ matrix.use-recipe != 'true' && (matrix.flavor || 'system') || '' }}
 
     - name: Install extra Linux deps
       if: runner.os == 'Linux'

test/Analyses/ActivityReverse.cpp

@@ -3,7 +3,6 @@
 // RUN: %cladclang -Xclang -plugin-arg-clad -Xclang -enable-va -Xclang -plugin-arg-clad -Xclang -disable-tbr %s -I%S/../../include -oActivity.out
 // RUN: ./Activity.out | %filecheck_exec %s
 //CHECK-NOT: {{.*error|warning|note:.*}}
-// XFAIL: valgrind
 
 #include "clad/Differentiator/Differentiator.h"
 

test/Analyses/TBR.cpp

@@ -2,7 +2,6 @@
 // RUN: ./TBR.out | %filecheck_exec %s
 // RUN: %cladclang %s -I%S/../../include -oTBR.out
 // RUN: ./TBR.out | %filecheck_exec %s
-// XFAIL: valgrind
 
 #include "clad/Differentiator/Differentiator.h"
 

test/Arrays/ArrayInputsReverseMode.C

@@ -2,7 +2,6 @@
 // RUN: ./ArrayInputsReverseMode.out | %filecheck_exec %s
 // RUN: %cladclang %s -I%S/../../include -Wno-unused-value -oArrayInputsReverseMode.out
 // RUN: ./ArrayInputsReverseMode.out | %filecheck_exec %s
-// XFAIL: valgrind
 
 #include "clad/Differentiator/Differentiator.h"
 

test/CMakeLists.txt

@@ -90,7 +90,13 @@ option(CLAD_CUDA_TEST_USE_SANITIZER "Run Clang cuda tests with compute-sanitizer
 option(CLAD_TEST_USE_VG "Run Clang tests under Valgrind" OFF)
 set(CLAD_TEST_EXTRA_ARGS --verbose --show-skipped --show-unsupported)
 if(CLAD_TEST_USE_VG)
-  set(CLAD_TEST_EXTRA_ARGS ${CLAD_TEST_EXTRA_ARGS} "--vg --vg-arg=-q")
+  # Run under memcheck with no suppression file, so the LLVM build under
+  # test shows its raw uninitialised-read behaviour: a clean row means the
+  # build is valgrind-clean, a failing one is triaged from the log.
+  # --gen-suppressions=all prints a ready-to-reuse stanza for every error,
+  # keyed on the exact frames, should any turn out to need suppressing.
+  set(CLAD_TEST_EXTRA_ARGS ${CLAD_TEST_EXTRA_ARGS}
+      "--vg --vg-arg=-q --vg-arg=--gen-suppressions=all")
 endif ()
 if(CLAD_CUDA_TEST_USE_SANITIZER)
   set(CLAD_TEST_EXTRA_ARGS ${CLAD_TEST_EXTRA_ARGS} "--param" "cuda_sanitizer=1")

test/ErrorEstimation/Assignments.C

@@ -1,6 +1,5 @@
 // RUN: %cladclang -I%S/../../include -oAssignments.out %s 2>&1 | %filecheck %s
 // RUN: ./Assignments.out | %filecheck_exec %s
-// XFAIL: valgrind
 
 #include "clad/Differentiator/Differentiator.h"
 #include "../TestUtils.h"

test/ErrorEstimation/BasicOps.C

@@ -1,6 +1,5 @@
 // RUN: %cladclang %s -I%S/../../include -Xclang -verify -oBasicOps.out 2>&1 | %filecheck %s
 // RUN: ./BasicOps.out | %filecheck_exec %s
-// XFAIL: valgrind
 
 #include "clad/Differentiator/Differentiator.h"
 #include "../TestUtils.h"

test/ErrorEstimation/ConditonalStatements.C

@@ -1,6 +1,5 @@
 // RUN: %cladclang -I%S/../../include -oCondStmts.out %s 2>&1 | %filecheck %s
 // RUN: ./CondStmts.out | %filecheck_exec %s
-// XFAIL: valgrind
 
 #include "clad/Differentiator/Differentiator.h"
 #include "../TestUtils.h"

test/ErrorEstimation/LoopsAndArrays.C

@@ -1,6 +1,5 @@
 // RUN: %cladclang -I%S/../../include -oLoopsAndArrays.out %s 2>&1 | %filecheck %s
 // RUN: ./LoopsAndArrays.out | %filecheck_exec %s
-// XFAIL: valgrind
 
 #include "clad/Differentiator/Differentiator.h"
 #include "../TestUtils.h"

test/ErrorEstimation/LoopsAndArraysExec.C

@@ -1,6 +1,5 @@
 // RUN: %cladclang %s -I%S/../../include -oLoopsAndArraysExec.out 2>&1 | %filecheck %s
 // RUN: ./LoopsAndArraysExec.out | %filecheck_exec %s
-// XFAIL: valgrind
 
 #include "clad/Differentiator/Differentiator.h"
 #include "../TestUtils.h"